How Things Work Final

You are flying a kite on a long string and the kite hovers motionless in the sky as the wind blows past it. The kite is high up to your east and you are pulling the kite string downward and westward. In which direction is the kite pushing on the air that passes it? (A) Downward and westward. (B) Upward and eastward. (C) Upward and westward. (D) Downward and eastward.

(A) Downward and westward.

What change can you make to a pendulum to increase its period of oscillation—that is, the time it takes to complete one full cycle of oscillation? (A) Increase the length of the pendulum. (B) Increase the amplitude of the pendulum's motion (the spatial extent of its motion). (C) Increase the acceleration due to gravity. (D) Increase the mass of the pendulum.

(A) Increase the length of the pendulum.

Suppose it's a hot summer day, but the air in your room is much colder than the outdoor air. If you remove 1 J of thermal energy from the cold room air and add that 1 J of thermal energy to the hot outdoor air, without doing anything else at all, what happens to the total entropy (disorder) of world? (A) It decreases. (B) It remains constant because you add as much entropy to the outdoor air as you remove from the indoor air. (C) It increases. (D) It remains constant because entropy is conserved.

(A) It decreases.

You and your friend carry identical water bottles from the first floor to the fifth floor. You start side-by-side and you finish side-by-side, but one of you uses the stairs while the other climbs straight up a ladder. Which of you did the most work on your water bottle? (A) Neither. You both do the same work on the water bottle. (B) The person who uses the stairs does the most work on the water bottle. (C) The person who climbs the ladder does the most work on the water bottle. (D) The person who takes the most time to reach the fifth floor does the most work on the water bottle.

(A) Neither. You both do the same work on the water bottle.

You place balls of cookie dough on a shiny metal cookie sheet and pop the sheet into the oven. The oven is being heated by an electric heating element at the bottom of the oven. How does heat flow from the heating element to the cookies? (A) Primarily by convection of the air. (B) Equally by conduction, convection, and radiation in the air. (C) Primarily by conduction through the air. (D) Primarily by radiation through the air.

(A) Primarily by convection of the air.

A typical heat pump (an air conditioner run backwards so that it heats the indoor air) consumes 2000 watts of electric power. How much thermal power does it provide to the indoor air? (A) Significantly more than 2000 watts. (B) About 1800 watts. (C) About 2000 watts. (D) About 200 watts.

(A) Significantly more than 2000 watts.

A sculptor is working with three non-flammable materials: a silvery metal, a black ceramic, and a white ceramic. When the sculptor heats these three materials to 1800 °C, they all begin to glow with visible thermal radiation. Which material glows most brightly? (A) The black ceramic. (B) They are all glowing with equal brightness. (C) The white ceramic. (D) The silvery metal.

(A) The black ceramic.

You toss a bottle straight up. Disregarding any effects due to the air, what force or forces are acting on the bottle while it is above your hands? (A) The bottle's weight. (B) The bottle's weight along with an upward force that steadily decreases until the bottle reaches its highest point. After that point, there is only the constant downward force of gravity. (C) A steadily decreasing upward force from the moment The bottle leaves your hands until it reaches its highest point and then a steadily increasing downward force as the bottle returns toward your hands. (D) The bottle's weight along with a steadily decreasing upward force.

(A) The bottle's weight.

You are pulling a wagon full of children up a hill at constant velocity. Which one of the following statements is true? (A) The net force on the wagon is zero and you are doing work on the wagon. (B) The net force on the wagon is zero and you are doing zero work on the wagon. (C) The net force on the wagon is uphill and you are doing zero work on the wagon. (D) The net force on the wagon is uphill and you are doing work on the wagon.

(A) The net force on the wagon is zero and you are doing work on the wagon.

You place three nonflammable objects among the red-hot coals of a roaring fire. The objects are identical in shape and size, but one object is black, another is white, and the third is shiny silver. After a few minutes, all three objects are at the same temperature: 1800 °C. They remain solid and are now glowing with thermal radiation. Which one is glowing most brightly? (A) The object that original appeared black. (B) The object that originally appeared silver. (C) The object that originally appeared white. (D) They are all glowing with equal brightness.

(A) The object that original appeared black.

You place three nonflammable objects among the red-hot coals of a roaring fire. The objects are identical in shape and size, but one object is black, another is white, and the third is shiny silver. After a few minutes, all three objects are at the same temperature: 1800 °C. They remain solid and are now glowing with thermal radiation. Which one is glowing most brightly? (A) The object that original appeared black. (B) The object that originally appeared white. (C) The object that originally appeared silver. (D) They are all glowing with equal brightness.

(A) The object that original appeared black.

Two identical rooms at identical temperatures contain identical collections of atoms. In one room that collection consists of moist air and an empty bowl and in the other room that collection consists of dry air and a bowl full of water. Which of the two rooms has the greater entropy (disorder)? (A) The room containing moist air and an empty bowl has the greater entropy. (B) The two rooms have equal entropies because they have identical temperatures. (C) The two rooms have equal entropies because they contain identical collections of atoms. (D) The room containing dry air and the full bowl has the greater entropy.

(A) The room containing moist air and an empty bowl has the greater entropy.

The airflow around a dust particle is laminar. What force prevents that dust particle from falling rapidly to the ground and keeps it aloft for a long time? (A) Viscous drag. (B) Pressure drag. (C) Lift. (D) Induced drag.

(A) Viscous drag.

You are driving Northward on a highway when you come to a smooth 90° turn toward the right. You maintain a constant speed around the turn and are soon driving Eastward. During the middle of the turn, in which direction were you accelerating? (A) You were accelerating toward the Southeast. (B) You were accelerating toward the East. (C) You were accelerating toward the South. (D) You were accelerating toward the Northeast.

(A) You were accelerating toward the Southeast.

When smokejumpers parachute into forest fires, they have with them emergency tents made of shiny aluminum foil. If they're caught in the blaze, they lie flat on the dirt in a low spot with the aluminum tent propped just above them. If the fire passes quickly enough, they have a good chance of surviving it. The tent is made of aluminum because (A) aluminum reflects most thermal radiation from the fire. (B) aluminum does not conduct heat well. (C) aluminum blocks convective heat transfer from the fire. (D) aluminum does not burn.

(A) aluminum reflects most thermal radiation from the fire.

Two balls, one of which weighs twice as much as the other, roll off of a horizontal table together at the same initial velocity. In this situation, (A) both balls hit the floor at approximately the same time and at the same distance from the table. (B) both balls hit the floor at approximately the same time, but the heavier ball lands considerably farther from the table than the lighter ball does. (C) the heavier ball hits the floor first and it lands considerably closer to the table than the lighter ball does. (D) the heavier ball hits the floor first and it lands considerably farther from the table than the lighter ball does.

(A) both balls hit the floor at approximately the same time and at the same distance from the table.

You drop a cylindrical can of soup and its flat bottom lands hard on the cement floor. As the result of the liquid-filled can's violent impact with the floor, its sides bulge outward. The bulge(s) is/are located at the (A) bottom of the can. (B) top and bottom of the can, leaving the middle of the can unaffected. (C) middle of the can. (D) top of the can.

(A) bottom of the can.

If you try to cook vegetables with 100 °C air, it takes a long time. But if you cook those same vegetables with 100 °C steam, they cook quickly. This is because the steam (A) condenses on the colder vegetables and releases a large amount of heat to the vegetables. (B) causes moisture inside the vegetables to boil and absorb heat from the vegetables. (C) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. (D) causes moisture inside the vegetables to boil and transfer heat to the vegetables.

(A) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

If you ever get caught in a forest fire, you should try to prevent the fire from transferring heat to you. One possible approach is to find a patch of bare unburnable ground that is as low as possible and lie on that ground. That will nearly eliminate heat transfer to you via (A) conduction and convection, but it will still allow heat transfer via radiation. (B) conduction and radiation, but it will still allow heat transfer via convection. (C) conduction, convection, and radiation. (D) convection and radiation, but it will still allow heat transfer via conduction.

(A) conduction and convection, but it will still allow heat transfer via radiation.

When water rushing through a fire hose flows around a bend in that hose, its pressure changes. The water pressure (A) decreases near the inside of the bend and increases near the outside of the bend. (B) increases near the inside of the bend and increases near the outside of the bend. (C) decreases near the inside of the bend and decreases near the outside of the bend. (D) increases near the inside of the bend and decreases near the outside of the bend.

(A) decreases near the inside of the bend and increases near the outside of the bend.

An air conditioner is cooling the air inside your house on a hot summer day. As a result of the air conditioner's operation, the entropy (disorder) of the indoor air is (A) decreasing, the entropy of outdoor air is increasing, and the total entropy of both is increasing. (B) decreasing and the entropy of outdoor air is decreasing. (C) increasing, the entropy of outdoor air is decreasing, and the total entropy of both is increasing. (D) increasing and the entropy of outdoor air is increasing.

(A) decreasing, the entropy of outdoor air is increasing, and the total entropy of both is increasing.

The hotter it is outside, the more electric energy an air conditioner must use to remove each joule of heat from the 72 °F indoor air in your home. It must consume more electric energy on a hotter day because (A) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter. (B) entropy flows into your home faster when the outdoor air is hotter. (C) heat flows into your home faster when the outdoor air is hotter. (D) delivering that joule of heat to the outdoor air creates more entropy as the outdoor air gets hotter.

(A) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter.

A racecar is driving around a circular track at a steady speed of 100 mph (160 km/h). The net force on the racecar is (A) directed toward the center of the track. (B) zero. (C) directed along the racecar's velocity (along its direction of travel). (D) directed away from the center of the track.

(A) directed toward the center of the track.

A satellite is orbiting the earth in a not-quite-circular orbit. As it moves, the satellite is accelerating (A) directly toward the center of the earth. (B) nearly forward, in the direction of a perfect circle around the earth. (C) directly outward, away from the center of the earth. (D) exactly forward, in the direction that the satellite is heading.

(A) directly toward the center of the earth.

The houseware store you have just entered has a uniform temperature throughout. You pick up a heavy copper pot and place it on a soft, fabric mat. As a result of this contact, heat (A) does not flow at all. (B) flows from the fabric mat to the copper pot. (C) flows from the copper pot to the fabric mat. (D) flows from whichever is the more massive to whichever is the less massive.

(A) does not flow at all.

Water is flowing gently out of the end of a garden hose. You block off most of the hose's opening with your thumb and now the water sprays out at high speed because you (A) have slowed the water flow through hose and plumbing so that the water wastes less energy doing work against viscous forces. (B) are doing work on the water with your thumb and greatly increasing its total energy. (C) are compressing the water and increasing its density. (D) are keeping air from getting into the hose and reducing the pressure.

(A) have slowed the water flow through hose and plumbing so that the water wastes less energy doing working against viscous forces.

You are enjoying an elegant candlelit dinner for two but the waiter has been a little careless with the ice. Your glass of ice water contains 25% water and 75% ice, while your friend's glass contains 75% water and 25% ice. The temperature of your glass of ice water (A) is the same as that of your friend. (B) depends on when it was filled. The glass that was filled first will now be warmer than the glass that was filled second. (C) is higher than that of your friend. (D) is lower than that of your friend.

(A) is the same as that of your friend.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) speed or its density. (B) speed or its viscosity. (C) viscosity or its density. (D) pressure.

(A) speed or its density.

If you're trying to increase the pressure in the water distribution system by modifying the local water tower, you should make the water tower (A) taller. (B) wider. (C) narrower. (D) shorter

(A) taller.

On a humid summer day, perspiration doesn't cool you off much because (A) the air is almost saturated with water vapor, so there is almost no evaporation. (B) the water vapor in the air is moving too fast to condense on your skin as perspiration. (C) the air density is extremely low and its pressure is too low to permit water to evaporate. (D) the air density is extremely low and its pressure is too high to permit water to evaporate.

(A) the air is almost saturated with water vapor, so there is almost no evaporation.

Your French fries are getting cold as you wait for your server to bring you a new bottle of ketchup. In frustration, you decide to get the last bits of ketchup out of the old bottle by swinging it rapidly in a circle with the cap-end of the bottle pointing away from you. This technique works because (A) the bottle's rapid inward acceleration leaves the ketchup behind so that it drifts toward the cap-end of the bottle. (B) centrifugal force pushes the ketchup toward the cap-end of the bottle. (C) viscous forces push the ketchup toward the cap-end of the bottle. (D) the force of the ketchup's momentum pushes it toward the cap-end of the bottle.

(A) the bottle's rapid inward acceleration leaves the ketchup behind so that it drifts toward the cap-end of the bottle.

You make a sharp left turn in your car and your cellphone slips off the dashboard and out the right passenger window. The cellphone leaves the car because (A) the car did not exert enough leftward force on the cellphone to make the cellphone accelerate with the car. (B) the dashboard of the turning car tilted sharply to become a ramp and the downhill ramp force pushed the cellphone out the window. (C) the car exerted a rightward centrifugal force on the cellphone that pushed the cellphone out the window. (D) the cellphone's weight pulled the cellphone out the window.

(A) the car did not exert enough leftward force on the cellphone to make the cellphone accelerate with the car.

Goose down is the soft, fluffy feathers near a goose's skin. The reason that a goose down jacket keeps you so warm in the winter is that (A) the fine structure of the goose down traps air and prevents it from undergoing convection. (B) goose down's low average density reduces its buoyant force. (C) goose down's white coloring assists the radiative transfer of heat from the outer surface of the coat to your skin. (D) the fibrous material in goose down is a poorer conductor of heat than the air it displaces.

(A) the fine structure of the goose down traps air and prevents it from undergoing convection.

The ocean tides are caused primarily by (A) the moon's gravity distorting the earth's oceans. (B) the cycle of temperature variations that occur over the course of each day. (C) the centripetal acceleration of the earth's oceans as the earth rotates on its axis. (D) the earth's oceans experiencing sympathetic vibration in response to the earth's rotation.

(A) the moon's gravity distorting the earth's oceans.

Even though your Thanksgiving dinner consists of a tofu turkey, you discover that it contains a wishbone. Who knew? You and your cousin decide to break the wishbone; the one with the large piece gets their wish. Your cousin holds one end of the wishbone motionless as you pull the other end toward you rapidly. The wishbone snaps and you're left holding only a tiny fragment. Better luck next time! Breaking the wishbone required energy and that energy was provided by (A) you. (B) neither of you. It was instead provided by chemical potential energy in the wishbone itself. (C) your cousin. (D) both you and your cousin.

(A) you.

You are tossing popcorn straight up and catching it in your mouth. At the moment each piece of popcorn reaches its peak height, its velocity is (A) zero and its acceleration is downward. (B) downward and its acceleration is zero. (C) zero and its acceleration is zero. (D) downward and its acceleration is downward.

(A) zero and its acceleration is downward.

You are waterskiing at constant velocity on a calm lake while wearing a lifejacket. As you move across the water, you are doing (A) zero work on the jacket and it is doing zero work on you. (B) (positive) work on the jacket and it is doing negative work on you. (C) negative work on the jacket and it is doing (positive) work on you. (D) (positive) work on the jacket and it is doing (positive) work on you.

(A) zero work on the jacket and it is doing zero work on you.

You are at the gym, exercising on a step machine. You have one foot on each of the machine's pedals and you move those pedals up and down as you step. The pedals always push upward on your feet, but they push upward harder on your feet while moving downward than they do while moving upward. When during this exercise is your foot transferring energy to the pedal that it is touching? (A) When that pedal is accelerating. (B) As that pedal moves downward. (C) As that pedal moves either upward or down. (D) As that pedal moves upward.

(B) As that pedal moves downward.

Someone props open the door to your jazz club on a cold winter evening and the air temperature in the club decreases dramatically. The air pressure remains unchanged. How does this decrease in air temperature affect the sound of the Saxaphone (a wind instrument)? (A) Its loudness (amplitude of pressure fluctuation) increases. (B) Its frequency (pitch) decreases. (C) Its frequency (pitch) increases. (D) Its loudness (amplitude of pressure fluctuation) decreases.

(B) Its frequency (pitch) decreases.

A satellite is orbiting the earth in a circular orbit. It is high above the atmosphere. As it moves, the satellite is accelerating (A) outward, away from the center of the earth. (B) inward, toward the center of the earth. (C) backward, opposite the direction that the satellite is heading. (D) forward, in the direction that the satellite is heading.

(B) inward, toward the center of the earth.

You put a metal pot of water on the stove at sea level and begin heating the water. When the water's temperature reaches 100 °C (212 °F), the water begins to boil. As heat continues to flow into the boiling water, (A) its temperature begins rising more rapidly as the amount of water remaining in the pot decreases. (B) its temperature remains almost constant because that heat is being used to convert liquid water into gaseous steam. (C) water molecules begin leaving the water's surface for the first time and gaseous water starts rising above the pot. (D) its temperature decreases slightly because cold air is flowing into it to form the bubbles.

(B) its temperature remains almost constant because that heat is being used to convert liquid water into gaseous steam.

On a hot, humid day, the liquid perspiration on your wet skin doesn't do a very good job of cooling you off. If the air were less humid but had the same temperature, you'd cool off better because water molecules would (A) leave your wet skin less often. (B) land on your wet skin less often. (C) land on your wet skin more often. (D) leave your wet skin more often.

(B) land on your wet skin less often.

When you light a candle, its flame turns wax molecules and oxygen into water and carbon dioxide molecules. The molecules that form during this combustion have (A) less chemical momentum than the original wax and oxygen molecules. (B) less chemical potential energy than the original wax and oxygen molecules. (C) more chemical momentum than the original wax and oxygen molecules. (D) more chemical potential energy than the original wax and oxygen molecules.

(B) less chemical potential energy than the original wax and oxygen molecules.

You are standing behind a swing, pushing your little cousin on that swing. To make your cousin swing farther and faster, you should only push your cousin forward when your cousin is (A) on your side of the equilibrium position. (B) moving forward. (C) on the far side of the equilibrium position. (D) moving backward.

(B) moving forward.

If a golf ball were smooth rather than dimpled, it would (A) curve toward the right after being hit by the club of a right-handed golfer. (B) not travel as far after being hit by a golf club. (C) travel much farther after being hit by a golf club. (D) curve toward the left after being hit by the club of a right-handed golfer.

(B) not travel as far after being hit by a golf club.

If you place a window air conditioning unit on a table in the middle of your sealed room, plug it in, and turn it on, you will find that the average temperature of your room will (A) rise slightly for about one minute, then fall dramatically as the unit begins to function. (B) rise. (C) remain the same. (D) fall.

(B) rise.

You're playing tennis on a hot, humid day in August and you are covered with perspiration. Unfortunately, that perspiration doesn't cool you off much because (A) the air density is extremely low and its pressure is too low to permit water to evaporate. (B) the air is almost saturated with water vapor, so there is almost no evaporation. (C) the water vapor in the air is moving too fast to condense on your skin as perspiration. (D) the air density is extremely low and its pressure is too high to permit water to evaporate.

(B) the air is almost saturated with water vapor, so there is almost no evaporation.

Although you meant to sign up for "semester abroad," you accidently signed up for "semester aboard." You are now aboard a tiny, perfectly insulated spaceship in deep space. What a mistake! As you play solitaire aboard your tiny ship, (A) the energy of the ship and its contents is decreasing. (B) the entropy (disorder) of the ship and its contents is increasing. (C) the entropy (disorder) of the ship and its contents is decreasing. (D) the energy of the ship and its contents is increasing.

(B) the entropy (disorder) of the ship and its contents is increasing.

You are visiting a playground and you notice that a girl on one swing completes each full cycle of motion in much less time than a boy on another swing. The girl has a much shorter period of motion (time between cycles) than the boy because (A) the girl is much heavier than the boy. (B) the girl is riding on a much shorter swing than the boy is riding. (C) the girl is riding on a much taller swing than the boy is riding. (D) the girl is much lighter than the boy.

(B) the girl is riding on a much shorter swing than the boy is riding.

You are inflating a shiny plastic balloon with helium. The balloon starts as a thin, flat bag but it gradually gets thicker as it fills. At first, the thin plastic balloon doesn't float. But as you keep adding helium to the balloon and it gets thicker, it eventually begins floating because (A) the helium-filled balloon's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (B) the average pressure of the helium-filled balloon increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (C) the upward buoyant force on a balloon full of helium is larger than the buoyant force on an identical balloon full of air. (D) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight.

(D) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight.

A space-walking astronaut in orbit around the earth has a weight of 600 newtons. This means that the earth exerts a downward force of 600 newtons on the astronaut. How much upward force does she exert on the earth? (A) 600 newtons. (B) somewhat more than 600 newtons because she is accelerating downward. (C) 0 newtons because she is in free fall and is thus weightless. (D) somewhat less than 600 newtons because she is accelerating downward.

(A) 600 newtons.

A silver flute produces a tone as the flautist blows across a hole near the end of the flute. What is vibrating to produce this tone? (A) A column of air inside the flute is vibrating along its length. (B) The silver body of the flute is vibrating as a single arc in which its middle moves opposite its two ends. (C) The silver body of the flute is vibrating along its length. (D) The silver body of the flute is vibrating as a single arc in which its middle moves back and forth while its ends remain motionless.

(A) A column of air inside the flute is vibrating along its length.

If you tape coins to the two tines (arms) of a tuning fork, the frequency (or pitch) of that tuning fork will (A) remain unchanged, but its loudness will increase. (B) decrease. (C) increase. (D) remain unchanged, but its loudness will decrease.

(B) decrease.

Most clocks use harmonic oscillators as timekeepers because of what important characteristic of a harmonic oscillator? (A) A harmonic oscillator's period of oscillation does not depend on its amplitude (extent of motion). (B) A harmonic oscillator's amplitude (extent of motion) is constant, regardless of its total energy. (C) A harmonic oscillator's momentum is constant throughout its oscillation. (D) A harmonic oscillator's total energy is constant, regardless of its amplitude (extent of motion).

(A) A harmonic oscillator's period of oscillation does not depend on its amplitude (extent of motion).

You are a photographer, capturing images of divers as they plummet 20 meters (66 feet) to the ocean beneath a cliff. It takes each diver 2 seconds to fall from the cliff to the water and you want to photograph each diver after 1 second of falling. How far above the water should you aim your camera? (A) Approximately 15 meters above the water. (B) Approximately 9.8 meters above the water. (C) Approximately 10 meters above the water. (D) Approximately 10.2 meters above the water.

(A) Approximately 15 meters above the water.

An artist constructs a minimalist violin that has no wooden body at all. Instead, the violin's four strings are mounted on a thin streel rod. In fact, that is the entire violin! The strings are under tension and vibrate properly, but you can barely hear their sound. Why is this minimalist violin so quiet? (A) Because air flows easily around the narrow strings as they vibrate, they produce little sound. (B) Because the steel rod is thin, it bends as the strings vibrate and absorbs their sound. (C) Because the steel is magnetic, it attracts and traps the sound of the strings before that sound can escape into the room. (D) Because steel is so much more dense than wood, it reflects the strings' sound back to the strings.

(A) Because air flows easily around the narrow strings as they vibrate, they produce little sound.

You stretch a rope between two trees to serve as a clothesline. After plucking the rope by accident, you notice that it is vibrating slightly in its fundamental vibrational mode and that its period (time to complete 1 full cycle of motion) of 1 second. What could you do to the rope to increase (lengthen) that period? (A) Decrease the rope's tension, increase the rope's mass, or lengthen the rope. (B) Decrease the rope's tension, decrease the rope's mass, or shorten the rope. (C) Increase the rope's tension, decrease the rope's mass, or shorten the rope. (D) Increase the rope's tension, increase the rope's mass, or shorten the rope.

(A) Decrease the rope's tension, increase the rope's mass, or lengthen the rope.

You are flying a kite on a long string and the kite hovers motionless in the sky as the wind blows past it. The kite is high up to your east and you are pulling the kite string downward and westward. In which direction is the kite pushing on the air that passes it? (A) Downward and westward. (B) Upward and eastward. (C) Upward and westward. (D) Downward and eastward.

(A) Downward and westward.

As the temperature difference between indoor air and outdoor air decreases, the electric energy an air conditioner consumes as it moves one joule of heat also decreases. Why? (A) Less ordered energy must become thermal energy to make up for the entropy lost when heat moves against its natural direction of flow. (B) Less thermal energy must become ordered energy to make up for the entropy produced when heat moves against its natural direction of flow. (C) Less thermal energy must become ordered energy to make up for the entropy lost when heat moves against its natural direction of flow. (D) Less ordered energy must become thermal energy to make up for the entropy produced when heat moves against its natural direction of flow.

(A) Less ordered energy must become thermal energy to make up for the entropy lost when heat moves against its natural direction of flow.

You are watching an airshow at the local airport and an acrobatic airplane is flying upside down to impress the crowd. That airplane is traveling forward at a constant horizontal velocity, just 10 feet above the runway! In which direction is the overall force that the airplane exerts on the air? (A) The airplane is pushing the air directly downward. (B) The airplane is pushing the air downward and forward. (C) The airplane is pushing the air directly backward. (D) The airplane is pushing the air downward and backward.

(A) The airplane is pushing the air directly downward.

An airplane is cruising at constant velocity, 30,000 feet in the air. Which of the following correctly describes the situation above the airplane's wing? (A) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (B) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be greater than the local atmospheric pressure. (C) The airstream over the wing is traveling straight ahead, so the pressure just above the wing must equal the local atmospheric pressure. (D) The airstream over the wing is bending upward, away from the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

(A) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

As an orchestra warms up, the wind instruments (e.g., flutes, clarinets, oboes) and the air inside them actually become hotter. These instruments have openings and are not sealed. How does this warming process affect the average pressure and density of the air inside the wind instruments? (A) The average pressure does not change, but the average density decreases. (B) The average pressure decreases, but the average density does not change. (C) The average pressure does not change, but the average density increases. (D) The average pressure increases, but the average density does not change.

(A) The average pressure does not change, but the average density decreases.

When water flows through a nozzle, the water's pressure (A) increases and its speed also increases. (B) decreases but its speed increases. (C) decreases and its speed also decreases. (D) increases but its speed decreases.

(B) decreases but its speed increases.

As an orchestra warms up, the wind instruments (e.g., flutes, clarinets, oboes) and the air inside them actually become hotter. These instruments have openings and are not sealed. How does this warming process affect the average pressure and density of the air inside the wind instruments? (A) The average pressure does not change, but the average density decreases. (B) The average pressure increases, but the average density does not change. (C) The average pressure decreases, but the average density does not change. (D) The average pressure does not change, but the average density increases.

(A) The average pressure does not change, but the average density decreases.

You purchase an antique balance-ring clock. When you place the clock upright on your dresser, it keeps perfect time. A friend tips the clock gently onto its back, so that its face and hands are visible from above instead of from the side. How does this change in orientation affect the clock? (A) The clock continues to keep perfect time. (B) The clock runs fast (its hands move through the minutes and hours too quickly). (C) The clock stops operating because its balance ring cannot rotate back and forth in the new orientation. (D) The clock runs slow (its hands move through the minutes and hours too slowly).

(A) The clock continues to keep perfect time.

An automobile engine "knocks" when the gas in its cylinder ignites spontaneously rather than waiting for the sparkplug to ignite it. During which of the 4 strokes can this premature ignition occur? (A) The compression stroke (when the gas in the cylinder is being compressed). (B) The power stroke (when the gas in the cylinder is pushing the piston out of the cylinder). (C) The exhaust stroke (when gas is being ejected from the cylinder). (D) The intake stroke (when gas is being added to the cylinder).

(A) The compression stroke (when the gas in the cylinder is being compressed).

An automobile engine "knocks" when the gas in its cylinder ignites spontaneously rather than waiting for the sparkplug to ignite it. During which of the 4 strokes can this premature ignition occur? (A) The compression stroke (when the gas in the cylinder is being compressed). (B) The intake stroke (when gas is being added to the cylinder). (C) The exhaust stroke (when gas is being ejected from the cylinder). (D) The power stroke (when the gas in the cylinder is pushing the piston out of the cylinder).

(A) The compression stroke (when the gas in the cylinder is being compressed).

The air conditioner in your home is cooling the indoor air on a hot summer. As that electric air conditioner operates, what happens to the energy of the indoor air, the outdoor air, and the electric company? (A) The energies of the indoor air and the electric company decrease, and the energy of the outdoor air increases. (B) The energies of the indoor air and the outdoor air decrease, and the energy of the electric company increases. (C) The energies of the outdoor air and the electric company decrease, and the energy of the indoor air increases. (D) The energies of the indoor air and the outdoor air increase, and the energy of the electric company decreases.

(A) The energies of the indoor air and the electric company decrease, and the energy of the outdoor air increases.

Your new dorm room is too hot in the summer, so you decide to install a window air conditioning unit. Since your room has no window, you install the air conditioner between your room and a suitemate's room. When you plug it in and turn it on, the unit transfers heat from your room to your suitemate's room and your room becomes pleasantly cool. As the unit does its job, what is happening to entropy? (A) The entropy of your room is decreasing, the entropy of your suitemate's room is increasing, and the total entropy is not decreasing. (B) The entropy of your room is increasing, the entropy of your suitemate's room is decreasing, and the total entropy is constant. (C) The entropy of your room is increasing, the entropy of your suitemate's room is increasing. (D) The entropy of your room is decreasing, the entropy of your suitemate's room is decreasing.

(A) The entropy of your room is decreasing, the entropy of your suitemate's room is increasing, and the total entropy is not decreasing.

Two identical rooms at identical temperatures contain identical collections of atoms. In one room that collection consists of moist air and an empty bowl and in the other room that collection consists of dry air and a bowl full of water. Which of the two rooms has the greater entropy (disorder)? (A) The room containing moist air and an empty bowl has the greater entropy. (B) The two rooms have equal entropies because they contain identical collections of atoms. (C) The two rooms have equal entropies because they have identical temperatures. (D) The room containing dry air and the full bowl has the greater entropy.

(A) The room containing moist air and an empty bowl has the greater entropy.

If you pluck a guitar string at different points along its length, it will produce somewhat different sounds. What is different about the string when you pluck it at different points? (A) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it. (B) The string's fundamental vibrational frequency depends on its amplitude of vibration and that amplitude depends on where you pluck the string. (C) Where you pluck the string divides the string into two parts that vibrate separately, so where you pluck affects those two partial strings. (D) The string's fundamental vibrational frequency depends on where you plucking it.

(A) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it.

You are kayaking in Alaska. You reach forward with your paddle, lower the paddle into the water, and then pull the paddle backward. You accelerate forward. What force acts on the paddle to cause you to accelerate forward? (A) The water exerts a drag force on the paddle, pushing the paddle in the forward direction. (B) The water exerts a buoyant force on the paddle, pushing the paddle in the forward direction. (C) The force of the paddle's momentum pushes it in the forward direction. (D) The water exerts a lift force on the paddle, pushing the paddle in the forward direction.

(A) The water exerts a drag force on the paddle, pushing the paddle in the forward direction.

You have two cups in front of you, one filled with water and the other filled with honey. Honey has a much greater viscosity than water. Honey has a slightly greater density than water. If you stir both liquids at equal speeds using identical spoons, which liquid is more likely to become turbulent and why? (A) The water is more likely to become turbulent because it has the much smaller viscosity. (B) The water is more likely to become turbulent because it has the slightly smaller density. (C) The honey is more likely to become turbulent because it has the much larger viscosity. (D) The honey is more likely to become turbulent because it has the slightly larger density.

(A) The water is more likely to become turbulent because it has the much smaller viscosity.

You wake up one very cold winter morning to find the grass outside covered with frost. How did this ice form on the grass? (A) Water molecules from the moist air landed on the cold grass more frequently than they left the grass, and there was a net accumulation of water molecules as ice. (B) Heat from the warmer air became ice as it flowed to the colder grass (C) Water that normally evaporates from warm grass as water vapor instead evaporated as ice from the cold grass. (D) Heat from the colder air became ice as it flowed to the warmer grass

(A) Water molecules from the moist air landed on the cold grass more frequently than they left the grass, and there was a net accumulation of water molecules as ice.

Water is flowing smoothly through a garden hose that rests on level ground. The hose bends toward the left and the water follows that bend. Neglecting any effects due to the water's viscosity, compare the water just inside the left and right sides of that bend. (A) Water on the left side has lower pressure and higher speed than water on the right side. (B) Water on the left side has lower pressure and lower speed than water on the right side. (C) Water on the left side has higher pressure and lower speed than water on the right side. (D) Water on the left side has higher pressure and higher speed than water on the right side.

(A) Water on the left side has lower pressure and higher speed than water on the right side.

To avoid tipping over while turning right on a bicycle, why must you lean the bicycle toward your right? (A) You accelerate rightward as you turn right and your inertia tends to make you tip over toward your left. By leaning toward your right, you cancel that tendency and avoid tipping over. (B) Leaning the bicycle decreases the downward force that the ground exerts on its wheels and reduces your downward acceleration. (C) Leaning the bicycle increases the upward force that the ground exerts on its wheels and reduces your downward acceleration. (D) Leaning the bicycle reduces the frictional force that the ground exerts on its wheels and reduces its tendency to tip over during the turn.

(A) You accelerate rightward as you turn right and your inertia tends to make you tip over toward your left. By leaning toward your right, you cancel that tendency and avoid tipping over.

You work at a camp and play the bugle, a simple musical horn with a single brass pipe. Despite having no valves to change the length of that pipe, you can produce several different notes (or pitches) from the bugle to wake everyone up at dawn. What are you doing to change the notes (or pitches) of the bugle? (A) You are causing the column of air inside the pipe to vibrate in its different vibrational modes, each of which has a different pitch. (B) You are changing the diameter of the brass pipe and changing the pitch at which it vibrates. (C) You are changing the mass of the brass pipe and changing the pitch at which it vibrates. (D) You are changing the tension in the brass pipe and changing the pitch at which it vibrates.

(A) You are causing the column of air inside the pipe to vibrate in its different vibrational modes, each of which has a different pitch.

A cup of water is in thermal equilibrium. If you stir the water vigorously, the water will become hotter. What causes this rise in temperature? (A) You do work as you stir the water and that work becomes thermal energy in the turbulent liquid. (B) You are making the water move as though it were boiling, so that it becomes hotter. (C) You are encouraging the conduction of heat from the cup to the water. (D) You are forcing convection to occur so that heat flows more rapidly from the cup to the water.

(A) You do work as you stir the water and that work becomes thermal energy in the turbulent liquid.

You and your friend are riding a carousel. Your horses are side-by-side and your friend is closer to the center of the carousel than you are. As the carousel turns steadily, which of the following is true? (A) You experience a larger inward acceleration than your friend does. (B) You and your friend experience equal inward accelerations, but your friend's speed is larger than your speed. (C) Your friend experiences a larger inward acceleration than you do. (D) You and your friend experience equal inward accelerations, but your speed is larger than your friend's speed.

(A) You experience a larger inward acceleration than your friend does.

The chemical bond that causes two oxygen atoms to cling together as an oxygen molecules is (A) a deficit of energy—the work needed to separate those two atoms from one another. (B) a myth; the two atoms only think that they are bound to one another. (C) an attractive force that the two atoms exert on one another when they are at their equilibrium separation. (D) a repulsive force that the two atoms exert on one another when they are at their equilibrium separation.

(A) a deficit of energy�the work needed to separate those two atoms from one another.

A cross-country skier is struggling to get up a hill, so you offer to help. As the skier passes you, you reach out with your hand and exert an uphill force of 80 N (18 pounds) on the skier. When you do this, the skier exerts (A) a downhill force of 80 N on you. (B) a downhill force of somewhat more than 80 N on you. (C) a downhill force of somewhat less than 80 N on you. (D) no downhill force on you at all.

(A) a downhill force of 80 N on you.

Two children are balanced on a seesaw, but one child weighs twice as much as the other child. The heavier child is sitting half as far from the pivot as is the lighter child. Since the seesaw is balanced, the heavier child is exerting on the seesaw (A) a torque that is equal in amount but oppositely directed to the torque the lighter child is exerting. (B) a torque that is less than the torque the lighter child is exerting. (C) a force that is less than the force the lighter child is exerting. (D) a force that is equal in amount but oppositely directed to the force the lighter child is exerting.

(A) a torque that is equal in amount but oppositely directed to the torque the lighter child is exerting.

Wrapping a hot potato in aluminum foil helps keep the potato warm because the shiny aluminum foil is (A) a very poor emitter of thermal radiation. (B) a poor conductor of heat, so the surface temperature of the foil is much less than the surface temperature of the potato. (C) so thin that it doesn't have enough mass to cool the potato significantly. (D) actually transparent to infrared radiation and allows radiant heat from the room to enter the potato and keep it warm.

(A) a very poor emitter of thermal radiation.

A rigid two-blade wind turbine that is experiencing zero net torque (A) has a constant angular velocity, which may be zero. (B) is motionless and horizontal. (C) has an angular velocity that is gradually decreasing toward zero. (D) is motionless and may be horizontal or tilted.

(A) has a constant angular velocity, which may be zero.

When smokejumpers parachute into forest fires, they have with them emergency tents made of shiny aluminum foil. If they're caught in the blaze, they lie flat on the dirt in a low spot with the aluminum tent propped just above them. If the fire passes quickly enough, they have a good chance of surviving it. The tent is made of aluminum because (A) aluminum reflects most thermal radiation from the fire. (B) aluminum does not conduct heat well. (C) aluminum does not burn. (D) aluminum blocks convective heat transfer from the fire.

(A) aluminum reflects most thermal radiation from the fire.

You seal a leftover sprig of parsley in a large zippered plastic bag and put them in the refrigerator. There was a substantial volume of air trapped in the bag, but the air's volume decreases as the refrigerator cools the bag. The decrease in the bag's temperature caused (A) an increase in the density of the air inside the bag. (B) a decrease in the density of the air inside the bag. (C) an increase in the pressure of the air inside the bag. (D) a decrease in the pressure of the air inside the bag.

(A) an increase in the density of the air inside the bag.

If you try to cook vegetables with 100 °C air, it takes a long time. But if you cook those same vegetables with 100 °C steam, they cook quickly. This is because the steam (A) condenses on the colder vegetables and releases a large amount of heat to the vegetables. (B) causes moisture inside the vegetables to boil and absorb heat from the vegetables. (C) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. (D) causes moisture inside the vegetables to boil and transfer heat to the vegetables.

(A) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

You watch from the ground as a crane lifts a large bucket of cement upward to a construction project. The bucket and cement are moving straight upward at constant velocity. As the crane's cable lifts the bucket, the cable is (A) doing work on the bucket and the bucket is doing work on the cement it contains. (B) not doing work on the bucket, but the bucket is doing work on the cement it contains. (C) doing work on the bucket, but the bucket is not doing work on the cement it contains. (D) not doing work on the bucket or the cement it contains.

(A) doing work on the bucket and the bucket is doing work on the cement it contains.

You are riding a roller coaster and your speed is increasing as you plunge downhill on the first hill. Your acceleration is directed (A) downhill, your feeling of acceleration is directed uphill, and your apparent weight is smaller in amount than your actual weight. (B) downhill, your feeling of acceleration is directed downhill, and your apparent weight is directed vertically downward. (C) vertically downward, your feeling of acceleration is directed vertically upward, and your apparent weight is vertically upward. (D) vertically downward, your feeling of acceleration is directed vertically upward, and your apparent weight is smaller in amount than your actual weight.

(A) downhill, your feeling of acceleration is directed uphill, and your apparent weight is smaller in amount than your actual weight.

You are competing in an "egg toss" event in which pairs of people toss raw eggs back and forth at gradually increasing distances. The winning pair is the one that tosses the egg the greatest distance without breaking it. To catch your egg without breaking it, you must allow that egg to push your hands a long distance in the direction of its velocity, a pushing process that takes a long period of time. Allowing your hands to move with the egg in this manner is crucial because it allows your hands to (A) extract both the egg's kinetic energy and the egg's forward momentum while exerting only small forces on the egg. (B) extract the egg's kinetic energy while exerting only small forces on it, but leaves the egg's forward momentum unchanged. (C) convert both the egg's kinetic energy and the egg's forward momentum into entropy in your hand. (D) extract the egg's forward momentum while exerting only small forces on it, but leaves the egg's kinetic energy unchanged.

(A) extract both the egg's kinetic energy and the egg's forward momentum while exerting only small forces on the egg.

To catch a football successfully, you should allow the ball to push your hands in the direction of its travel. Allowing your hands to move with the football is crucial because it allows you to (A) extract energy from the football. (B) extract momentum from the football. (C) add momentum to the football. (D) add energy to the football.

(A) extract energy from the football.

To put a satellite in orbit around the earth, a rocket has two important tasks. First, the rocket must lift the satellite above the Earth's atmosphere. Second, the rocket must (A) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the Earth rather than descending to the ground. (B) give the satellite such a large upward vertical speed that the falling satellite cannot descend to the ground. (C) push upward on the satellite with a force that balances the satellite's downward weight so that the satellite can coast at constant velocity. (D) give the satellite such a large sideways acceleration that the satellite's apparent weight is zero.

(A) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the Earth rather than descending to the ground.

If you blow carefully across the top of a drinking straw, it will emit a tone. If you now close off the bottom of the straw with your finger, the tone that it emits will (A) go down by an octave (its frequency will decrease by a factor of 2). (B) stay the same. (C) go up by an octave (its frequency will increase by a factor of 2). (D) go down by a fifth (its frequency will decrease by a factor of 1.5).

(A) go down by an octave (its frequency will decrease by a factor of 2).

If you strike a stiff, spring-like surface with a mallet and listen to the sound it emits, you'll notice that this sound is more complicated than that emitted by a string or a thin bar. That's because surfaces (A) have overtones that are not integer multiples of their fundamental frequencies. (B) are harmonic oscillators. (C) have overtones that are integer multiples of their fundamental frequencies. (D) are not harmonic oscillators.

(A) have overtones that are not integer multiples of their fundamental frequencies.

Wearing a thin nylon jacket with no additional insulation still helps you stay warm on a cold, windy day. The primary way in which the jacket keeps you warm is by (A) helping you retain a thin layer of warm air near your skin. (B) preventing radiation from transferring heat from your skin to your surroundings. (C) increasing the overall pressure drag force you experience from the wind. (D) preventing conduction from transferring heat from your skin to your surroundings.

(A) helping you retain a thin layer of warm air near your skin.

Flowing honey is less likely to become turbulent than flowing water because (A) honey's larger viscosity favors laminar flow. (B) honey's larger density favors laminar flow. (C) water's larger pressure favors turbulent flow. (D) water's larger viscosity favors turbulent flow.

(A) honey's larger viscosity favors laminar flow.

On a cold winter day, you partially fill a Ziploc plastic bag with warm indoor air, seal it, and set it outside to cool off. A few minutes later, you notice that the bag seems to have deflated somewhat. The temperature of the air inside the bag has decreased, resulting in a significant (A) increase in the density of the air inside the bag. (B) increase in the pressure inside the bag. (C) decrease in the pressure inside the bag. (D) decrease in the density of the air inside the bag.

(A) increase in the density of the air inside the bag.

At the cruising altitude of a commercial jet plane, the air's density is too low to support life. The plane must therefore compress the outside air before sending it into the pressurized cabin. After compressing the air, the plane must send that air through an air conditioner because the act of compressing that air (A) increases the air's temperature. (B) reduces the air's energy. (C) turns it into a liquid and the air conditioner helps it evaporate back into a gas. (D) increases the air's momentum.

(A) increases the air's temperature.

Increasing the amount of carbon dioxide (a greenhouse gas) in the earth's atmosphere (A) increases the altitude of the earth's effective radiating surface. (B) has no effect on the earth's thermal radiation or the effective surface that emits that thermal radiation. (C) decreases the rate at which the earth radiates heat into space. (D) increases the rate at which the earth radiates heat into space.

(A) increases the altitude of the earth's effective radiating surface.

A sealed bottle of perfume is sitting on a dresser in a thermally isolated room. A spring pops the lid off the perfume bottle and the air in the room gradually acquires a beautiful scent. While the room air is developing its scent, the total entropy in the thermally isolated room is (A) increasing. (B) decreasing. (C) staying constant because the room is thermally isolated. (D) staying constant because entropy is conserved.

(A) increasing.

You throw a curve ball that is bending toward your right as it travels away from you. It is able to bend in this manner because (A) it is deflecting the airflow around it toward your left. (B) it is deflecting the airflow around it toward your right as well. (C) you gave it a rightward push as it came out of your fingers. (D) the pressure in front of it is higher than the pressure behind it.

(A) it is deflecting the airflow around it toward your left.

It's a warm summer day and you're having lunch outdoors on a patio. A window air conditioning unit hums quietly nearby as it cools an office inside the building. Your friend notices that the unit's outdoor part is emitting a considerable amount of heat and comments on how strange that is. You explain correctly that the air conditioner's outside part is emitting the heat (A) it removes from the inside air and the heat it produces from the electricity it consumes. (B) it produces from the electricity it consumes. (C) that is left over when it converts thermal energy from the inside air into electricity. (D) it produces during its defrost cycle; when it warms up its evaporator to remove ice that forms because of the humidity.

(A) it removes from the inside air and the heat it produces from the electricity it consumes.

If you're trying to increase the pressure in the water distribution system by modifying the local water tower, you should make the water tower (A) taller. (B) wider. (C) narrower. (D) shorter.

(A) taller.

As the water stream from a fountain rises upward in the open air, its gravitational potential energy increases, (A) its kinetic energy decreases, but its pressure potential energy remains constant. (B) both its pressure potential energy and its kinetic energy decrease. (C) neither its pressure potential energy nor its kinetic energy change. (D) its pressure potential energy decreases, but its kinetic energy remains constant.

(A) its kinetic energy decreases, but its pressure potential energy remains constant.

As water flows downward in a vertical pipe that has a uniform diameter, the water's gravitational potential energy decreases, (A) its pressure potential energy increases, but its kinetic energy remains constant. (B) both its pressure potential energy and its kinetic energy increase. (C) its kinetic energy increases, but its pressure potential energy remains constant. (D) neither its pressure potential energy nor its kinetic energy change.

(A) its pressure potential energy increases, but its kinetic energy remains constant.

A pendulum consists of a metal ball hanging on a cable from a fixed point on the ceiling. To increase the period of that pendulum (the time it takes to complete one full cycle of motion), you should (A) lengthen the cable. (B) decrease the mass of the ball. (C) shorten the cable. (D) increase the mass of the ball.

(A) lengthen the cable.

When you light a candle, its flame turns wax molecules and oxygen into water and carbon dioxide molecules. The molecules that form during this combustion have (A) less chemical potential energy than the original wax and oxygen molecules. (B) more chemical potential energy than the original wax and oxygen molecules. (C) less chemical momentum than the original wax and oxygen molecules. (D) more chemical momentum than the original wax and oxygen molecules.

(A) less chemical potential energy than the original wax and oxygen molecules.

Your bottle of oil and vinegar salad dressing has separated, so that the oil is floating on the vinegar. You notice that a large herb is floating motionless at the interface between the oil and the vinegar. That herb's average density is (A) less than that of vinegar but more than that of oil. (B) more than that of either vinegar or oil. (C) less than that of either vinegar or oil. (D) less than that of oil but more than that of vinegar.

(A) less than that of vinegar but more than that of oil.

The maximum speed of a rocket-propelled spaceship with an exhaust speed of 5000 mph is (A) limited only by the ratio of fuel to spaceship. (B) 2500 mph. (C) 10000 mph. (D) 5000 mph.

(A) limited only by the ratio of fuel to spaceship.

Your table at a family-style restaurant has a "lazy Susan" in the middle. This large circular platform rotates frictionlessly so that you can "pass" an entree to your friends by placing it on the platform and then rotating the platform. When the server places a new entree on the platform, it (A) makes it harder to change the platform's angular velocity. (B) decreases the platform's angular velocity. (C) increases the platform's angular velocity. (D) makes it easier to change the platform's angular velocity.

(A) makes it harder to change the platform's angular velocity.

Two photographs show the same thermally isolated room containing the same air molecules, water molecules, and ceramic mug. In one photograph, the air is moist and the mug is empty. In the other photograph, the air is dry and the mug contains liquid water. Of these two photographs, the situation in which the air is moist and the mug is empty has (A) more entropy and less thermal energy. (B) more entropy and more thermal energy. (C) less entropy and less thermal energy. (D) less entropy and move thermal energy.

(A) more entropy and less thermal energy.

A rubber duck is floating motionless on the water in a bathtub and the top of the duck is exactly 4 inches above the water level. You pour a thin layer of bath oil onto the water. The top of the duck is now (A) more than 4 inches above the water level. (B) under the water level. (C) still 4 inches above the water level. (D) less than 4 inches above the water level.

(A) more than 4 inches above the water level.

Near sea level, water normally boils at about 100 °C (212 °F). However, a microwave oven can heat water in a glass container above that temperature if (A) no initial steam bubbles form within the liquid water. (B) the glass container does not conduct electricity. (C) the glass container remains colder than 100 °C (212 °F). (D) the water is very pure.

(A) no initial steam bubbles form within the liquid water.

An air conditioner's compressor takes low density gas and compresses that gas to high density. During this compression process, the gas's (A) temperature rises and so does its pressure. (B) temperature drops, but its pressure rises. (C) temperature stays the same, but its pressure rises. (D) temperature rises, but its pressure drops.

(A) temperature rises and so does its pressure.

The characteristic of a harmonic oscillator that makes it especially suitable for use as a timekeeper in a clock is that its (A) period of oscillation does not depend on its amplitude (extent of motion). (B) momentum is constant throughout its oscillation. (C) amplitude (extent of motion) is constant, regardless of its total energy. (D) total energy is constant, regardless of its amplitude (extent of motion).

(A) period of oscillation does not depend on its amplitude (extent of motion).

You are drying your hair and you have put a diffuser (an anti-nozzle) on the end of the dryer. As it goes through the diffuser, the air slows down and its (A) pressure increases. (B) momentum increases. (C) density decreases. (D) particle density decreases.

(A) pressure increases.

You are standing in the middle of a bus that is moving forward on a level road at constant velocity. Suddenly, another passenger accidentally spills an enormous container of salad oil and the floor becomes perfectly slippery. It cannot exert any frictional forces on your feet. Because nothing else is touching you, you (A) remain in the middle of the bus. (B) shift toward the side of the bus (perpendicular to the direction of its velocity). (C) shift toward the front of the bus (in the direction of its velocity). (D) shift toward the back of the bus (opposite its velocity).

(A) remain in the middle of the bus.

You are standing in the middle of a level subway car that is moving forward at constant velocity when another passenger accidentally spills an enormous container of olive oil. Suddenly, the floor cannot exert any frictional forces on your feet. Because nothing else is touching you, you (A) remain in the middle of the subway car. (B) shift toward the front of the subway car (in the direction of its velocity). (C) shift toward the side of the subway car (perpendicular to the direction of its velocity). (D) shift toward the back of the subway car (opposite its velocity).

(A) remain in the middle of the subway car.

You are practicing tennis alone by hitting a tennis ball forward toward a cement wall. Each time the ball hits the wall, it bounces backward at high speed so that you can hit it again. During its bounce, the ball (A) retains approximately all of its energy but transfers more forward momentum than it had to the wall. (B) retains approximately all of its energy but transfers most of its momentum to the wall. (C) retains approximately all of its energy and momentum. (D) retains approximately all of its momentum but transfers most of its energy to the wall.

(A) retains approximately all of its energy but transfers more forward momentum than it had to the wall.

To win a stuffed animal at the state fair, you simply need to drop a glass marble onto a stationary glass plate and have the marble come to rest on that plate. Unfortunately, when the marble hits the plate, it bounces upward because the marble (A) retains essentially all of its energy but transfers a large amount of momentum to the plate. (B) retains essentially all of its energy and momentum. (C) transfers a large amount of momentum and energy to the plate. (D) retains essentially all of its momentum but transfers a large amount of energy to the plate.

(A) retains essentially all of its energy but transfers a large amount of momentum to the plate.

You purchase an antique wall clock that uses a pendulum as its timekeeper. The seller, who lives in Northern Canada truthfully said that the clock keeps perfect time. When you mount it on the wall of your dorm room, where the earth's gravity is slightly weaker, the clock (A) runs a little slow (causing you to be late for classes). (B) continues to keep perfect time because the period of a pendulum depends only on its length and not on the strength of gravity. (C) runs a little fast (causing you to be early for classes). (D) continues to keep perfect time because the period of a pendulum depends only on its mass and not on the strength of gravity.

(A) runs a little slow (causing you to be late for classes).

Your grandfather clock uses a pendulum as its timekeeper. At home, that clock keeps perfect time. When you move the clock to your dorm room, where the earth's gravity is slightly weaker than at home, the clock (A) runs a little slow (causing you to be late for classes). (B) continues to keep perfect time because the period of a pendulum depends only on its mass and not on the strength of gravity. (C) continues to keep perfect time because the period of a pendulum depends only on its length and not on the strength of gravity. (D) runs a little fast (causing you to be early for classes).

(A) runs a little slow (causing you to be late for classes).

On a humid summer day, perspiration doesn't cool you off much because (A) the air's relative humidity is almost 100%, so there is almost no evaporation. (B) the air density is extremely low and its pressure is too low to permit water to evaporate. (C) the water vapor in the air is moving too fast to condense on your skin as perspiration. (D) the air density is extremely low and its pressure is too high to permit water to evaporate.

(A) the air's relative humidity is almost 100%, so there is almost no evaporation.

A weather balloon is used to study the atmosphere as it float upward. The balloons starts as an empty rubber bag, but adding helium to it gradually inflates the balloon until it is many feet in diameter. At first, the balloon doesn't float. As you keep adding helium to it and it grows larger, however, it eventually begins floating because (A) the average density of the helium-filled balloon decreases as it fills and its density eventually becomes less than that of the air it displaces. (B) the average pressure of the helium-filled balloon increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (C) the upward buoyant force on a balloon full of helium is larger than the buoyant force on an identical balloon full of air. (D) the helium-filled balloon's weight decreases as you put more lightweight helium particles inside it and it eventually becomes weightless.

(A) the average density of the helium-filled balloon decreases as it fills and its density eventually becomes less than that of the air it displaces.

A candle is burning in a closed box that is perfectly insulated and isolated from the rest of the world. Because the candle is burning, (A) the entropy (disorder) of the box and its contents is increasing. (B) the energy of the box and its contents is decreasing. (C) the entropy (disorder) of the box and its contents is decreasing. (D) the energy of the box and its contents is increasing.

(A) the entropy (disorder) of the box and its contents is increasing.

You are studying for final exams in a perfectly insulated and isolated room. Absolutely nothing passes into or out of this room, not even sound, light, electricity, or heat. As you study in this special room, (A) the entropy (disorder) of the room and its contents is increasing. (B) the entropy (disorder) of the room and its contents is decreasing. (C) the energy of the room and its contents is increasing. (D) the energy of the room and its contents is decreasing.

(A) the entropy (disorder) of the room and its contents is increasing.

When the cylinder in an automobile's engine is going through the compression stroke, the piston squeezes the fuel and air mixture into a smaller volume within the cylinder. As the piston moves into the cylinder, the piston does work on the fuel and air mixture and (A) the pressure, density, and temperature of the gas all increase. (B) the pressure and temperature of the gas increase, but the density of the gas remains unchanged. (C) the pressure and density of gas increase, but the temperature of the gas remains unchanged. (D) the density and temperature of the gas increase, but the pressure of the gas remains unchanged.

(A) the pressure, density, and temperature of the gas all increase.

After clearing the bar in the high jump, you land softly on a giant mattress. Landing on the mattress is much more comfortable than landing on a sand heap of equal size because you transfer (A) the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you. (B) the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more mass to stop you. (C) more momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop. (D) less momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop.

(A) the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you.

Because of bad planning during the design and construction of a high-rise apartment building, all 50 floors of the building receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) the same on all floors, but the speed of the spraying water is smaller on higher floors. (B) the same on all floors, but the speed of the spraying water is greater on higher floors. (C) greater on higher floors. (D) smaller on higher floors.

(A) the same on all floors, but the speed of the spraying water is smaller on higher floors.

You are inflating a shiny plastic balloon with helium. The balloon starts as a thin, flat bag but it gradually gets thicker as it fills. At first, the thin plastic balloon doesn't float. But as you keep adding helium to the balloon and it gets thicker, it eventually begins floating because (A) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight. (B) the average pressure of the helium-filled balloon increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (C) the helium-filled balloon's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (D) the upward buoyant force on a balloon full of helium is larger than the buoyant force on an identical balloon full of air.

(A) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight.

You are swinging a bucket full of water around you in a big horizontal circle at a constant speed. You are at the center of its circular path. The net force on the bucket points directly (A) toward you. (B) along the bucket's velocity (along its direction of travel). (C) away from you. (D) downward.

(A) toward you.

You are swinging a bucket full of water around you in a big horizontal circle at a constant speed. You are at the center of its circular path. The net force on the bucket points directly (A) toward you. (B) downward. (C) away from you. (D) along the bucket's velocity (along its direction of travel).

(A) toward you.

You are a patent examiner for the government and the invention you are examining claims to convert heat continuously into electric power. According to the inventor, when you put this device in the middle of a room and turn it on, it gradually cools the room air while providing a steady and endless supply of electric power. You wisely reject this patent application because, in order to work as described, it would have to have to (A) violate the law of entropy. (B) turn work into heat, or more precisely, into thermal energy. (C) violate the law of conservation of energy. (D) turn stored energy into power.

(A) violate the law of entropy.

Ice cubes gradually shrink in a frost-free freezer because (A) water molecules go directly from solid ice to gaseous water vapor. (B) the ice melts periodically and some of it evaporates before it can refreeze. (C) the ice melts periodically and some of it drips into the bottom of the freezer. (D) the freezer gremlins like to carve their initials on the ice cubes.

(A) water molecules go directly from solid ice to gaseous water vapor.

After clearing the bar in the high jump, you land softly on a giant mattress. Landing on the mattress is much more comfortable than landing on a sand heap of equal size because (A) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you. (B) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress has more mass than the sand. (C) you transfer less momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop. (D) you transfer more momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop.

(A) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you.

It's a snowy day and you are pulling your sled up a hill. Both you and the sled are moving at constant velocity. The net force on you is (A) zero and the net force on the sled is zero. (B) directed uphill and the net force on the sled is directed downhill. (C) directed uphill and the net force on the sled is directed uphill. (D) directed downhill and the net force on the sled is directed uphill.

(A) zero and the net force on the sled is zero.

You are pushing a shopping cart up a ramp. Both you and the cart are moving at constant velocity. The net force on the shopping cart is (A) zero and the net force on you is zero. (B) directed downhill and the net force on you is directed uphill. (C) directed uphill and the net force on you is directed uphill. (D) directed uphill and the net force on you is directed downhill.

(A) zero and the net force on you is zero.

A bottle in both thermal and phase equilibrium at 0 °C contains 1 kilogram of ice and 1 kilogram of liquid water. You move the bottle to a new location and allow it to reach equilibrium at -0.5 °C. The bottle now contains (A) 0.5 kilograms of ice and 1.5 kilograms of liquid water. (B) 2 kilograms of ice. (C) 1.5 kilograms of ice and 0.5 kilograms of liquid water. (D) 1 kilogram of ice and 1 kilogram of liquid water.

(B) 2 kilograms of ice.

A bottle in both thermal and phase equilibrium at 0 °C contains 1 kilogram of ice and 1 kilogram of liquid water. You move the bottle to a new location and allow it to reach equilibrium at 0.5 °C. The bottle now contains (A) 1 kilogram of ice and 1 kilogram of liquid water. (B) 2 kilograms of liquid water. (C) 1.5 kilograms of ice and 0.5 kilograms of liquid water. (D) 0.5 kilograms of ice and 1.5 kilograms of liquid water.

(B) 2 kilograms of liquid water.

While most western musical instruments are based on harmonic oscillators, there are some instruments that are not harmonic oscillators. What feature of an instrument's sound would indicate that it is not a harmonic oscillator? (A) A rapid decrease in the loudness of its sound. (B) A change in its pitch (vibrational frequency) as the loudness of its sound decreases. (C) A rapid increase in the loudness of its sound. (D) The absence of a change in its pitch (vibrational frequency) as the loudness of its sound decreases.

(B) A change in its pitch (vibrational frequency) as the loudness of its sound decreases.

A gold flute produces a tone as the flautist blows across a hole near the end of the flute. What is vibrating to produce this tone? (A) The gold body of the flute is vibrating as a single arc in which its middle moves opposite its two ends. (B) A column of air inside the flute is vibrating along its length. (C) The gold body of the flute is vibrating along its length. (D) The gold body of the flute is vibrating as a single arc in which its middle moves back and forth while its ends remain motionless.

(B) A column of air inside the flute is vibrating along its length.

Which of the following is a harmonic oscillator? (A) A mass with a stable equilibrium that experiences a restoring force that is independent of its displacement from equilibrium. (B) A mass with a stable equilibrium that experiences a restoring force that is proportional to its displacement from equilibrium. (C) A mass with an unstable equilibrium that accelerates in the direction opposite its velocity. (D) A mass with an unstable equilibrium that accelerates at constant velocity near that equilibrium.

(B) A mass with a stable equilibrium that experiences a restoring force that is proportional to its displacement from equilibrium.

You are trying to win a prize at the state fair by knocking a massive can off a shelf. You have a choice of 4 different objects to throw at the can, each with a mass of 1 kg. With which of the following objects are you most likely to win? (A) A soft bean bag. (B) A stiff bouncy ball. (C) A soft bouncy ball. (D) A stiff bean bag.

(B) A stiff bouncy ball.

How is a steam engine able to obtain work (ordered energy) from hot steam? (A) The hot steam has a large amount of entropy and that entropy can be converted into work. (B) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work. (C) The hot steam has a large amount of momentum and that momentum can be converted into work. (D) The steam's thermal energy can be converted into work because both are energy and energy is conserved.

(B) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work.

You are trying to set the world's record for drinking water through the tallest drinking straw. You only need to drink one drop of water, so speed doesn't matter. What could you do to have the best chance of setting this record? (A) Go to the highest altitude available, preferably at the top of a tall mountain. (B) Go to the lowest altitude available, preferably sea level or below. (C) Use the widest drinking straw you can fit in your mouth. (D) Use the narrowest drinking straw you can find.

(B) Go to the lowest altitude available, preferably sea level or below.

A metal ball hanging from a coil spring can bounce up and down as a harmonic oscillator. Which of the following changes will increase the ball's period—that is, the time it takes the ball to complete one full cycle of its bouncing motion? (A) Decrease the amplitude of the ball's motion—that is, the extent of the ball's motion above and below equilibrium. (B) Increase the ball's mass. (C) Increase the amplitude of the ball's motion—that is, the extent of the ball's motion above and below equilibrium. (D) Increase the spring's stiffness.

(B) Increase the ball's mass.

It's just below freezing outside and your walkway has a layer of slippery ice on it. Which of the following substances will cause that ice to melt if you sprinkle it on the ice? (A) Salt, sugar, and sand. (B) Salt, sugar, but not sand. (C) Salt, sand, but not sugar. (D) Salt, but not sand or sugar.

(B) Salt, sugar, but not sand.

If you're designing an energy efficient automobile, why should you minimize the diameter of the turbulent wake it leaves behind in the air? (A) Since air in the wake has higher than atmospheric density, having less air in the wake means less inertia to overcome. (B) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted momentum. (C) Since the automobile exhaust heats air in the wake, having less air in the wake means less heat extracted from the car. (D) Since air in the wake has higher than atmospheric pressure, having less air in the wake means less pressure pushing on the rear of the car.

(B) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted momentum.

You take some very cold ice cubes out of the freezer and place them on the warm granite countertop. The ice cubes begin to make noises: they creak, groan, and even crack. Sound carries ordered energy, yet the ice cubes and granite countertop started with only thermal energy. Why did the sound only appear when the ice cubes touched the granite countertop? (A) The cold ice is too hard to vibrate with sound energy and needs to warm up until it begins to melt. (B) Some of the granite's thermal energy can only become work and sound as heat flows from the hotter granite to the colder ice. (C) Sound, like heat, can only flow from hotter objects to colder objects. (D) The ice's thermal energy increases most rapidly when it is at the same temperature as the warm granite.

(B) Some of the granite's thermal energy can only become work and sound as heat flows from the hotter granite to the colder ice.

On a windless day, a pitcher throws a baseball toward home plate without any significant spin. After the ball has passed through the air, in which direction is the air moving on average? (A) The air is moving upward. (B) The air is moving toward home plate. (C) The air is moving away from home plate. (D) The air is moving downward.

(B) The air is moving toward home plate.

You drop a bag of flour onto a trampoline and the bag rebounds upward almost to its original height. Compare the bag's energy and momentum just before it bounced on the trampoline with its energy and momentum just after bounced off the trampoline. (A) The bag's energy changed significantly, but its momentum changed only a little. (B) The bag's energy changed only a little, but its momentum changed significantly. (C) The bag's energy and momentum changed only a little. (D) The bag's energy and momentum changed significantly.

(B) The bag's energy changed only a little, but its momentum changed significantly.

You drop an extremely bouncy rubber ball on a cement floor and it rebounds upward almost to its original height. Compare the ball's energy and momentum just before it bounced on the floor with its energy and momentum just after bounced off the floor. (A) The ball's energy and momentum changed only a little. (B) The ball's energy changed only a little, but its momentum changed significantly. (C) The ball's energy and momentum changed significantly. (D) The ball's energy changed significantly, but its momentum changed only a little.

(B) The ball's energy changed only a little, but its momentum changed significantly.

You drop an extremely bouncy rubber ball on a cement floor and it rebounds upward almost to its original height. Compare the ball's energy and momentum just before it bounced on the floor with its energy and momentum just after bounced off the floor. (A) The ball's energy and momentum changed significantly. (B) The ball's energy changed only a little, but its momentum changed significantly. (C) The ball's energy and momentum changed only a little. (D) The ball's energy changed significantly, but its momentum changed only a little.

(B) The ball's energy changed only a little, but its momentum changed significantly.

You drop an extremely bouncy rubber ball on a cement floor and it rebounds upward almost to its original height. Compare the ball's energy and momentum just before it bounced on the floor with its energy and momentum just after it bounced off the floor. (A) The ball's energy changed significantly, but its momentum changed only a little. (B) The ball's energy changed only a little, but its momentum changed significantly. (C) The ball's energy and momentum changed only a little. (D) The ball's energy and momentum changed significantly.

(B) The ball's energy changed only a little, but its momentum changed significantly.

You add a teaspoon of salt to a glass of pure water. The salt initially sits at the bottom of the water, but it slowly dissolves so that eventually you have a glass of salt water. Which has more entropy: the glass of pure water with salt sitting at its bottom or the glass of salt water? (A) They have the same entropy because entropy is conserved. (B) The glass of salt water has more entropy. (C) They have the same entropy because water's entropy is independent of its purity. (D) The glass of pure water with salt at its bottom has more entropy.

(B) The glass of salt water has more entropy.

A friend has purchased an old pendulum clock at a yard sale. Its pendulum is discolored, so your friend applies a thick layer of brass-colored spray paint. That paint increases the pendulum's mass and its weight. How does painting the pendulum affect the pendulum's period? [Ignore effects due to the air and other insignificant influences.] (A) The pendulum's period increases (more time). (B) The pendulum's period is unchanged. (C) The pendulum becomes unstable and does not swing back and forth anymore. It there has no period. (D) The pendulum's period decreases (less time.)

(B) The pendulum's period is unchanged.

As spacecraft travels from Earth to Mars, it is exposed to full sunlight continuously for about six months. Since nothing is touching that spacecraft, why doesn't the spacecraft continue to get hotter and hotter? (A) Because it is isolated from the sun by empty space, the sun's heat can't reach it and it doesn't experience any changes in temperature. (B) The spacecraft's temperature rises until it is able to radiate heat away into space as fast as that heat arrives from the sun. (C) It uses an air conditioner to eliminate the excess thermal energy as rapidly as it arrives. (D) It has solar panels that convert the sun's thermal radiation completely into electricity and avoids any need to eliminate heat.

(B) The spacecraft's temperature rises until it is able to radiate heat away into space as fast as that heat arrives from the sun.

A pitcher throws a spinning baseball toward home plate and the baseball curves toward the pitcher's right. Why did the baseball curve? (A) The spinning baseball had angular momentum toward the left and the ball reacted to this angular momentum by pushing itself toward the right. (B) The spinning baseball deflected the passing air toward the pitcher's left. (C) The pitcher pushed the spinning baseball toward the right and the pitcher's rightward force caused the baseball to accelerator toward the right. (D) The spinning baseball had angular momentum toward the right and that angular momentum bent its path toward the right.

(B) The spinning baseball deflected the passing air toward the pitcher's left.

You're at a lovely outdoor café in New Orleans during the summer and the ice in your glass of water is gradually melting. That glass contained 75% ice and 25% water when it was first poured but now contains 25% ice and 75% water. How has the temperature of the water in that glass changed since it was poured? (A) The temperature of the water has increased by 2 °F. (B) The temperature of the water has remained constant. (C) The temperature of the water has increased by 4 °F. (D) The temperature of the water has increased by 8 °F.

(B) The temperature of the water has remained constant.

Since a water molecule weighs less than the average air molecule, humid air is less dense than dry air. Suppose that the humidity of the air increases significantly during an orchestra concert. How will the resulting decrease in air density affect the wind instruments (e.g., flutes, clarinets, oboes)? (A) Their volumes (amplitudes of vibration) will increase. (B) Their pitches (frequencies of vibration) will increase. (C) Their volumes (amplitudes of vibration) will decrease. (D) Their pitches (frequencies of vibration) will decrease.

(B) Their pitches (frequencies of vibration) will increase.

You are riding a bus that is moving straight ahead at high speed. The bus comes to a curve in the road and begins to turn toward the left. You find yourself pressed against the right side of your seat. What force, if any, is pushing you toward the right? (A) A friction force from the seat is pushing you toward the right. (B) There is no force pushing you toward the right. (C) A support force from the seat is pushing you toward the right. (D) The force of your momentum is pushing you toward the right.

(B) There is no force pushing you toward the right.

You are carrying a child on your back as you walk down a hill. The child is traveling straight at a steady speed. In which direction is the force you are exerting on the child? (A) Downhill (in the direction of your velocity). (B) Upward (vertical). (C) Forward (horizontal). (D) Upward and forward (between vertical and horizontal).

(B) Upward (vertical).

Flowing pancake syrup is less likely to become turbulent than flowing water because (A) water's larger pressure favors turbulent flow. (B) water's larger viscosity favors turbulent flow. (C) pancake syrup's larger viscosity favors laminar flow. (D) pancake syrup's larger density favors laminar flow.

(C) pancake syrup's larger viscosity favors laminar flow.

You wake up one very cold winter morning to find the grass outside covered with frost. How did this ice form on the grass? (A) Water that normally evaporates from warm grass as water vapor instead evaporated as ice from the cold grass. (B) Water molecules from the moist air landed on the cold grass more frequently than they left the grass, and there was a net accumulation of water molecules as ice. (C) Heat from the warmer air became ice as it flowed to the colder grass (D) Heat from the colder air became ice as it flowed to the warmer grass

(B) Water molecules from the moist air landed on the cold grass more frequently than they left the grass, and there was a net accumulation of water molecules as ice.

Water is flowing smoothly through horizontal plumbing. As the water move through a bend in that pipe, compare the water on the inside of the bend to water on the outside of the bend. (A) Water on the inside has lower pressure and lower speed than water on the outside. (B) Water on the inside has lower pressure and higher speed than water on the outside. (C) Water on the inside has higher pressure and lower speed than water on the outside. (D) Water on the inside has higher pressure and higher speed than water on the outside.

(B) Water on the inside has lower pressure and higher speed than water on the outside.

A tall flagpole is topped by a metal ball. When a large bird leaps off the ball, the flagpole starts bending back and forth rhythmically about its straight equilibrium shape. At what moment(s) during its rhythmic motion is the ball moving fastest? (A) Just before the flagpole is bent furthest away from equilibrium. (B) When the ball is coasting through equilibrium. (C) When the flagpole is bent furthest away from equilibrium. (D) Just after the flagpole is bent furthest away from equilibrium.

(B) When the ball is coasting through equilibrium.

You are at a tropical resort and your friends have talked you into diving off the top of a cliff into the ocean below. It's a 4-second fall to the ocean. When you have been falling for exactly 2 seconds, you change your mind and instantly grab onto the tree projecting outward from the cliff. Miraculously, you stop safely and hold onto the tree. Your decision to climb up or down now depends on your height on the cliff. Where are you and the tree located on that cliff? [Note: neglect any effects due to the air.] (A) You are midway between the top of the cliff and the ocean. (B) You are much closer to the top of the cliff than to the ocean below. (C) You are much closer to the ocean than to the top of the cliff above. (D) You are slightly above the midway point between the top of the cliff and the ocean.

(B) You are much closer to the top of the cliff than to the ocean below.

You and several friends take turns bungee jumping from Beta Bridge, using the same spring-like bungee cord. Near the end of your turn, you bounce gently up and down on the cord with a period (the time it takes for each bounce) of 1 second. One friend has your same height, but is heavier than you. Another friend has your same weight, but is shorter than you. During your friends' turns, what are the periods of their bounces? (A) Your heavier friend has a period longer than 1 second, your shorter friend has a period longer than 1 second. (B) Your heavier friend has a period longer than 1 second, your shorter friend has a period of 1 second. (C) Your heavier friend has a period of 1 second, your shorter friend has a period longer than 1 second. (D) Your heavier friend has a period of 1 second, your shorter friend has a period shorter than 1 second.

(B) Your heavier friend has a period longer than 1 second, your shorter friend has a period of 1 second.

You and several friends take turns bungee jumping from Beta Bridge, using the same spring-like bungee cord. Near the end of your turn, you bounce gently up and down on the cord with a period (the time it takes for each bounce) of 1 second. One friend has your same height, but is heavier than you. Another friend has your same weight, but is shorter than you. During your friends' turns, what are the periods of their bounces? (A) Your heavier friend has a period of 1 second; your shorter friend has a period shorter than 1 second. (B) Your heavier friend has a period longer than 1 second; your shorter friend has a period of 1 second. (C) Your heavier friend has a period of 1 second; your shorter friend has a period longer than 1 second. (D) Your heavier friend has a period longer than 1 second; your shorter friend has a period longer than 1 second.

(B) Your heavier friend has a period longer than 1 second; your shorter friend has a period of 1 second.

You are walking a dog on a leash when a squirrel runs by. Suddenly, you are all accelerating forward. If the dog is exerting a 50 newton forward force on the leash, the force that the leash is exerting on the dog is (A) zero. (B) a 50 newton backward force. (C) less than a 50 newton backward force (but not zero). (D) more than a 50 newton backward force.

(B) a 50 newton backward force.

When you blow gently across the top of a particular soda bottle, it emits a tone. The column of air in the bottle is vibrating up and down in its fundamental mode. If you replace the air in the bottle with helium and then blow gently across the top of the bottle, it will emit (A) a tone at the same pitch as before. (B) a tone at a higher pitch than before. (C) no sound at all. (D) a tone at a lower pitch than before.

(B) a tone at a higher pitch than before.

Ice cannot be colder than (A) 0 °F (-17.8°C). (B) absolute zero. (C) 32 °F (0 °C). (D) -32 °F (-35.6 °C).

(B) absolute zero.

To transform 1 kilogram of boiling-hot water at 100 °C into 1 kilogram of steam at 100 °C, you must (A) allow the water to boil for more than 5 minutes, although it doesn't require any additional heat. (B) add a large amount of heat to the water. (C) allow the water to boil for less than 5 minutes, although it doesn't require any additional heat. (D) remove a large amount of heat to the water.

(B) add a large amount of heat to the water.

A hot air balloon is passing over your head when the pilot turns on the flame and heats up the air inside the balloon's envelope (the balloon's fabric skin). That envelope is open at the bottom, where the flame heats it. As the temperature of the air inside the unsealed envelope increases, the (A) air molecules flow into the envelope's opening and the pressure of the air inside the envelope increases. (B) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases. (C) air molecules flow into the envelope's opening and the density of the air inside the envelope increases. (D) upward buoyant force on the balloon increases and it begins to rise.

(B) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

A hot air balloon is passing over your head when the pilot turns on the flame and heats up the air inside the balloon's envelope (the balloon's fabric skin). That envelope is open at the bottom, where the flame heats it. As the temperature of the air inside the unsealed envelope increases, the (A) air molecules flow into the envelope's opening and the pressure of the air inside the envelope increases. (B) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases. (C) air molecules flow into the envelope's opening and the density of the air inside the envelope increases. (D) upward buoyant force on the balloon increases and it begins to rise.

(B) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

After preventing a score, the goalie kicks the soccer ball toward midfield. The soccer ball gradually slows down, even though it is travelling almost horizontally. The primary reason for this slowing is that the (A) air pressure at the front and back of the ball is greater than atmospheric pressure, while the air pressure on the sides of the ball is less than atmospheric. (B) air pressure at the front of the ball is greater than atmospheric pressure, while the air pressure behind the ball is approximately atmospheric. (C) air pressure at the front of the ball is equal to atmospheric pressure, while the air pressure behind the ball is less than atmospheric. (D) air pressure at the front and back of the ball is less than atmospheric pressure, while the air pressure on the sides of the ball is more than atmospheric.

(B) air pressure at the front of the ball is greater than atmospheric pressure, while the air pressure behind the ball is approximately atmospheric.

You are fond of boiled eggs, which you normally cook for 3 minutes while in Charlottesville. You are casually hiking on Mt. Everest, 29,000 feet above sea level, and stop for a snack. You put an egg in a pot of boiling water and wait 3 minutes. Sadly, the egg turns out badly undercooked because the reduced atmospheric pressure in the mountains (A) reduces the density of air bubbles inside the boiling water so that those bubbles do not conduct heat well. (B) allows bubbles of pure steam to exist and grow inside the water at a temperature well below 100 °C (212 °F). (C) reduces the density of air bubbles inside the boiling water so that those bubbles do not undergo convection well and cannot heat the egg quickly enough. (D) causes the hot air bubbles in the boiling water to expand too quickly and rise out of the water before they have a chance to heat the egg.

(B) allows bubbles of pure steam to exist and grow inside the water at a temperature well below 100 °C (212 °F).

A skateboarder rides swiftly up the edge of a bowl-shaped surface and leaps into the air. While in the air, the skateboarder flips upside and tosses the skateboard from hand to hand. The skateboarder then rides safely back down the bowl. During the time that the skateboarder and skateboard are not touching anything, one aspect of their motion that is constant is their total (or combined) [note: neglect any effects due to the air] (A) momentum. (B) angular momentum. (C) velocity. (D) angular velocity.

(B) angular momentum.

If you heat water in a glass container in the microwave oven for a long time and notice that it isn't boiling during the last few seconds of cooking, you would be wise to (A) lean over it and stare at the liquid to see if it's hot. (B) avoiding getting close to it until you're sure that it has cooled below its boiling temperature. (C) put your finger in the liquid to see if it's hot. (D) sip it to see if it's hot.

(B) avoiding getting close to it until you're sure that it has cooled below its boiling temperature.

Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand removes less energy from you because it (A) stops the downward motion of your foot faster and thus absorbs less of your momentum. (B) barely moves downward as you push downward on it, so you do almost zero work on it. (C) stops the downward motion of your foot faster and thus absorbs more of your momentum. (D) pushes up on your foot just as hard as your foot pushes down on it, unlike the soft dry sand.

(B) barely moves downward as you push downward on it, so you do almost zero work on it.

You drop a cylindrical can of soup and its flat bottom lands hard on the cement floor. As the result of the liquid-filled can's violent impact with the floor, its sides bulge outward. The bulge(s) is/are located at the (A) top of the can. (B) bottom of the can. (C) middle of the can. (D) top and bottom of the can, leaving the middle of the can unaffected.

(B) bottom of the can.

You drop a cylindrical can of tomato sauce and its flat bottom lands hard on the cement floor. As the result of the liquid-filled can's violent impact with the floor, its sides bulge outward. The bulge(s) is/are located at the (A) top and bottom of the can, leaving the middle of the can unaffected. (B) bottom of the can. (C) top of the can. (D) middle of the can.

(B) bottom of the can.

You are designing a chair for a museum. While your chair will be a work of art, it must also be practical and it mustn't tip over easily. To ensure that it stays upright, you design it so that its (A) velocity always remains constant if you tip it. (B) center of gravity always rises if you tip it. (C) angular velocity always remains constant if you tip it. (D) center of gravity always descends if you tip it.

(B) center of gravity always rises if you tip it.

When water rushing through a fire hose flows around a bend in that hose, its pressure changes. The water pressure (A) increases near the inside of the bend and decreases near the outside of the bend. (B) decreases near the inside of the bend and increases near the outside of the bend. (C) increases near the inside of the bend and increases near the outside of the bend. (D) decreases near the inside of the bend and decreases near the outside of the bend.

(B) decreases near the inside of the bend and increases near the outside of the bend.

As heat flows from hot soup to a cold kitchen, the entropy (disorder) of the soup (A) increases, the entropy of the kitchen decreases, and their combined entropy remains unchanged. (B) decreases, the entropy of the kitchen increases, and their combined entropy increases. (C) increases, the entropy of the kitchen decreases, and their combined entropy increases. (D) decreases, the entropy of the kitchen increases, and their combined entropy remains unchanged.

(B) decreases, the entropy of the kitchen increases, and their combined entropy increases.

As heat flows from a hot woodstove to a cold room, the entropy of the woodstove (A) decreases, the entropy of the room increases, and their combined entropy remains unchanged. (B) decreases, the entropy of the room increases, and their combined entropy increases. (C) increases, the entropy of the room decreases, and their combined entropy remains unchanged. (D) increases, the entropy of the room decreases, and their combined entropy increases.

(B) decreases, the entropy of the room increases, and their combined entropy increases.

The elevator in a fancy hotel has table in it and there is a vase of flowers on that table. As the elevator rises at constant velocity toward the penthouse suite, the table is (A) doing zero work on the vase of flowers because the vase and flowers are moving at constant velocity. (B) doing (positive) work on the vase of flowers. (C) doing zero work on the vase of flowers because the table is rigid. (D) doing negative work on the vase of flowers.

(B) doing (positive) work on the vase of flowers.

You watch from the ground as a crane lifts a large bucket of cement upward to a construction project. The bucket and cement are moving straight upward at constant velocity. As the crane's cable lifts the bucket, the cable is (A) not doing work on the bucket, but the bucket is doing work on the cement it contains. (B) doing work on the bucket and the bucket is doing work on the cement it contains. (C) not doing work on the bucket or the cement it contains. (D) doing work on the bucket, but the bucket is not doing work on the cement it contains.

(B) doing work on the bucket and the bucket is doing work on the cement it contains.

A gust of wind shakes your home and causes a hanging chandelier to begin swinging gently back and forth on its support chain. When its overall motion is small, the time it takes the chandelier to complete one full oscillation of that motion (its period of oscillation) does not depend on (A) the chandelier's weight, but it does depend on the chandelier's amplitude of motion. (B) either the chandelier's weight or the chandelier's amplitude of motion. (C) the length of the chain supporting the chandelier. (D) the chandelier's amplitude of motion, but it does depend on the chandelier's weight.

(B) either the chandelier's weight or the chandelier's amplitude of motion.

An automobile's internal combustion engine burns a mixture of fuel and air in its cylinders. It is impossible for this engine to convert all of the chemical potential energy of the fuel and air mixture into mechanical work because burning that mixture increases its (A) pressure. (B) entropy. (C) energy. (D) momentum.

(B) entropy.

The temperature of the air in a concert hall is increasing although its pressure is not. As a result of this temperature rise, the hall's pipe organ (A) experiences a drop in pitch (its frequencies decrease). (B) experiences a rise in pitch (its frequencies increase). (C) maintains the same pitch but experiences a decrease in loudness. (D) maintains the same pitch but experiences an increase in loudness.

(B) experiences a rise in pitch (its frequencies increase).

You are washing your car by spraying water at it from a hose and nozzle. At the center of the stream of water, right where it hits the car, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches the car is (A) equal to atmospheric pressure. (B) greater than atmospheric pressure. (C) less than atmospheric pressure, but more than zero. (D) exactly zero.

(B) greater than atmospheric pressure.

You're drinking a cup of hot coffee in an airplane at 35,000 feet. Suddenly the airplane pressurization system fails and the cabin's air pressure decreases abruptly. The coffee begins to boil because its temperature (A) has suddenly decreased. (B) hasn't changed but bubbles of pure steam are now stable inside it. (C) hasn't changed but the air bubbles inside it have suddenly expanded. (D) has suddenly increased.

(B) hasn't changed but bubbles of pure steam are now stable inside it.

If you strike a stiff, spring-like surface with a mallet and listen to the sound it emits, you'll notice that this sound is more complicated than that emitted by a string or a thin bar. That's because surfaces (A) are not harmonic oscillators. (B) have overtones that are not integer multiples of their fundamental frequencies. (C) are harmonic oscillators. (D) have overtones that are integer multiples of their fundamental frequencies.

(B) have overtones that are not integer multiples of their fundamental frequencies.

Water is flowing gently out of the end of a garden hose. You block off most of the hose's opening with your thumb and now the water sprays out at high speed because you (A) are keeping air from getting into the hose and reducing the water pressure. (B) have reduced the water's speed in the hose so that it wastes less of its ordered energy. (C) are doing work on the water with your thumb and greatly increasing its ordered energy. (D) are compressing the water and increasing its density.

(B) have reduced the water's speed in the hose so that it wastes less of its ordered energy.

You are cleaning the siding on your house by spraying water at it from a hose and nozzle. At the center of the stream of water, right where it hits the siding, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches the siding is (A) exactly zero. (B) higher than atmospheric pressure. (C) equal to atmospheric pressure. (D) lower than atmospheric pressure, but more than zero.

(B) higher than atmospheric pressure.

You are cleaning the siding on your house by spraying water at it from a hose and nozzle. At the center of the stream of water, right where it hits the siding, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches the siding is (A) lower than atmospheric pressure, but more than zero. (B) higher than atmospheric pressure. (C) equal to atmospheric pressure. (D) exactly zero.

(B) higher than atmospheric pressure.

You are playing with a squirt gun and the narrow stream of water from your toy hits your friend's cheek. At the center of the stream of water, right where it hits his cheek, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches his cheek is (A) exactly zero. (B) higher than atmospheric pressure. (C) lower than atmospheric pressure, but more than zero. (D) equal to atmospheric pressure.

(B) higher than atmospheric pressure.

As a soccer ball moves swiftly through the air, it experiences pressure drag because the air pressure (A) below the ball is higher than the air pressure above the ball. (B) in front of the ball is higher than the air pressure behind it. (C) in front of the ball is lower than the air pressure behind it. (D) around the ball is uniform everywhere.

(B) in front of the ball is higher than the air pressure behind it.

After drinking all the water in your plastic water bottle, you seal the bottle closed and place it in the hot sun. A while later, you find that the bottle's sides are bent slightly outward so that it has slightly more volume than before. Since you sealed the bottle, the air pressure inside the bottle has (A) decreased and the air density inside the bottle has decreased. (B) increased and the air density inside the bottle has decreased. (C) increased and the air density inside the bottle has increased. (D) decreased and the air density inside the bottle has increased.

(B) increased and the air density inside the bottle has decreased.

At high altitude, a commercial jetliner must compress the outside air before circulating it in the pressurized cabin. The compressed air must first be sent through an air conditioner, however, because compressing air (A) increases its humidity. (B) increases its temperature. (C) turns it into a liquid and the air conditioner's evaporator allows it to return to a gas. (D) decreases its humidity.

(B) increases its temperature.

Increasing the amount of carbon dioxide (a greenhouse gas) in the earth's atmosphere (A) increases the rate at which the earth radiates heat into space. (B) increases the altitude of the earth's effective radiating surface. (C) has no effect on the earth's thermal radiation or the effective surface that emits that thermal radiation. (D) decreases the rate at which the earth radiates heat into space.

(B) increases the altitude of the earth's effective radiating surface.

An automobile engine becomes more energy efficient (better gas mileage) as the temperature reached when it burns fuel in air increases (when its flame becomes hotter) because increasing the temperature difference between the hot flame and the cold outdoor air (A) increases the momentum produced by transferring 1 joule of thermal energy from the flame to the air. (B) increases the entropy produced by transferring 1 joule of thermal energy from the flame to the air. (C) decreases the entropy produced by transferring 1 joule of thermal energy from the flame to the air. (D) decreases the momentum produced by transferring 1 joule of thermal energy from the flame to the air.

(B) increases the entropy produced by transferring 1 joule of thermal energy from the flame to the air.

In a famous ice skating trick, a skater begins spinning with her arms out and then pulls her arms tightly against her body. She is then spinning extremely fast on the tip of one skate. Her angular velocity increases because her angular momentum (A) increases but her rotational mass remains constant. (B) is constant but her rotational mass decreases. (C) decreases so she can spin faster. (D) is constant but her momentum decreases.

(B) is constant but her rotational mass decreases.

As the water stream from a fountain rises upward in the open air, its gravitational potential energy increases, (A) neither its pressure potential energy nor its kinetic energy change. (B) its kinetic energy decreases, but its pressure potential energy remains constant. (C) both its pressure potential energy and its kinetic energy decrease. (D) its pressure potential energy decreases, but its kinetic energy remains constant.

(B) its kinetic energy decreases, but its pressure potential energy remains constant.

On a hot, humid day, the liquid perspiration on your wet skin doesn't do a very good job of cooling you off. The weather changes and the air suddenly becomes less humid, although its temperature remains the same. You find that you're cooling off better because water molecules now (A) leave your wet skin more often, but land on your wet skin at the same rate as before. (B) land on your wet skin less often, but leave your wet skin at the same rate as before. (C) leave your wet skin less often, but land on your wet skin at the same rate as before. (D) land on your wet skin more often, but leave your wet skin at the same rate as before.

(B) land on your wet skin less often, but leave your wet skin at the same rate as before.

When you light a natural gas stove, its flame turns natural gas molecules and oxygen into water and carbon dioxide molecules. The molecules that form during this combustion have (A) less chemical momentum than the original natural gas and oxygen molecules. (B) less chemical potential energy than the original natural gas and oxygen molecules. (C) more chemical momentum than the original natural gas and oxygen molecules. (D) more chemical potential energy than the original natural gas and oxygen molecules.

(B) less chemical potential energy than the original natural gas and oxygen molecules.

When a wax candle burns in air, the water and carbon dioxide molecules that form as the result of combustion reactions have (A) more chemical momentum than the original wax and air molecules (B) less chemical potential energy than the original wax and air molecules (C) more chemical potential energy than the original wax and air molecules (D) less chemical momentum than the original wax and air molecules

(B) less chemical potential energy than the original wax and air molecules.

When wood burns in air, the water and carbon dioxide molecules that form as the result of combustion reactions have (A) less chemical momentum than the original wood and air molecules. (B) less chemical potential energy than the original wood and air molecules. (C) more chemical potential energy than the original wood and air molecules. (D) more chemical momentum than the original wood and air molecules.

(B) less chemical potential energy than the original wood and air molecules.

A friend suggests that you invest in a new invention that supposedly absorbs heat from the room and converts it into electricity. According to a brochure, the device sits in the middle of the room, gradually cooling the room air while providing a steady and endless supply of electric power. You wisely choose not to invest in the device because in order to work as described, it would have to do something impossible-it would have to (A) violate the conservation of energy. (B) lower the world's total entropy. (C) turn work into heat, or more precisely, into thermal energy. (D) turn stored energy into power.

(B) lower the world's total entropy.

The E string of a violin has a fundamental frequency of 660 Hz (660 cycles-per-second). If you cause that string to vibrate as three one-third strings, its loudness (A) will increase, but its pitch will remain unchanged at 660 Hz. (B) may or may not change, but its pitch will be 1980 Hz. (C) will decrease, but its pitch will remain unchanged at 660 Hz. (D) may or may not change, but its pitch will be 220 Hz.

(B) may or may not change, but its pitch will be 1980 Hz.

You are taking a self-defense class and are learning to get a heavy hanging bag swinging back and forth by hitting it at the proper moments during its swing. To make the bag swing further, you should punch it away from you every time it is (A) moving toward you. (B) moving away from you. (C) motionless at the moment it comes closest to you. (D) motionless at the moment it is farthest away from you.

(B) moving away from you.

The waiting room in a bus station gets cold in winter, so the company has installed an electric heater high on one wall where no one can accidently touch it. When that heater is turned on, it turns electric power directly into thermal power, like an electric toaster. Heat then flows from the heater to people seated on benches near the floor (A) equally poorly via conduction, convection, and radiation, and the room will remain cold. (B) primarily via radiation, with almost no heat flowing via conduction or convection. (C) equally well via conduction, convection, and radiation, and the room will become warm. (D) primarily via convection and radiation, with almost no heat flowing via conduction.

(B) primarily via radiation, with almost no heat flowing via conduction or convection.

Increasing the tension in a guitar string (A) raises the string's frequency (pitch) by softening the string's restoring force. (B) raises the string's frequency (pitch) by stiffening the string's restoring force. (C) lowers the string's frequency (pitch) by softening the string's restoring force. (D) lowers the string's frequency (pitch) by stiffening the string's restoring force.

(B) raises the string's frequency (pitch) by stiffening the string's restoring force.

You are standing in the middle of a level subway car that is moving forward at constant velocity when another passenger accidentally spills an enormous container of olive oil. Suddenly, the floor cannot exert any frictional forces on your feet. Because nothing else is touching you, you (A) shift toward the back of the subway car (opposite its velocity). (B) remain in the middle of the subway car. (C) shift toward the side of the subway car (perpendicular to the direction of its velocity). (D) shift toward the front of the subway car (in the direction of its velocity).

(B) remain in the middle of the subway car.

You are standing in the middle of a subway car that is moving forward at constant velocity when another passenger accidently spills an enormous container of olive oil. Suddenly, the floor cannot exert any frictional forces on your feet. Nothing else is touching you, so you (A) shift toward the side of the subway car (perpendicular to the direction of its velocity). (B) remain in the middle of the subway car. (C) shift toward the front of the subway car (in the direction of its velocity). (D) shift toward the back of the subway car (opposite its velocity).

(B) remain in the middle of the subway car.

When the A-string of a violin vibrates in its fundamental mode without anyone touching it, it has a frequency (or pitch) of 440 cycles per second. When that same string is vibrating at 880 cycles per second without anyone touching it, it is vibrating in its (A) fundamental mode, but traveling half as far during each vibrational cycle. (B) second harmonic mode, as 2 half-length strings. (C) fundamental mode, but traveling twice as far during each vibrational cycle. (D) fundamental mode, but completing the same motion twice as quickly.

(B) second harmonic mode, as 2 half-length strings.

If the earth had no atmosphere, the temperature at the earth's surface would be (A) almost that of empty space—a few degrees above absolute zero. (B) significantly cooler than it is now. (C) significantly hotter than it is now. (D) essentially the same as it is now.

(B) significantly cooler than it is now.

An electric space heater is perfectly efficient: it consumes 1500 watts of electric power and provides 1500 watts of thermal power to the indoor air. In comparison, a heat pump (an air conditioner run backwards so that it heats the indoor air) that consumes 1500 watts of electric power provides (A) about 1500 watts. (B) significantly more than 1500 watts of thermal power. (C) about 100 watts. (D) about 1000 watts.

(B) significantly more than 1500 watts of thermal power.

When a plane is flying through the air at 600 miles per hour, the air entering the inlet duct of its jet engine is traveling (A) faster than 600 miles per hour and its pressure is lower than atmospheric. (B) slower than 600 miles per hour and its pressure is higher than atmospheric. (C) slower than 600 miles per hour and its pressure is lower than atmospheric. (D) faster than 600 miles per hour and its pressure is higher than atmospheric.

(B) slower than 600 miles per hour and its pressure is higher than atmospheric.

When a plane is flying through the air at 600 miles per hour, the air entering the inlet duct of its jet engine is traveling (A) slower than 600 miles per hour and its pressure is lower than atmospheric. (B) slower than 600 miles per hour and its pressure is higher than atmospheric. (C) faster than 600 miles per hour and its pressure is higher than atmospheric. (D) faster than 600 miles per hour and its pressure is lower than atmospheric.

(B) slower than 600 miles per hour and its pressure is higher than atmospheric.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) pressure. (B) speed. (C) viscosity. (D) transparency.

(B) speed.

You are filling a plastic party balloon with helium. At first, the under-filled balloon doesn't float. But as you keep filling it with helium, it eventually begins floating because (A) the average pressure of the helium-filled balloon increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (B) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces. (C) the helium-filled bag's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (D) the upward buoyant force on a balloon full of helium is larger than the buoyant force on an identical balloon full of air.

(B) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces.

You're at the lake and watch two children jump off a dock at the same time. They both kick equally hard during their jumps, but one child jumps mostly upward while the other child jumps mostly forward. After they leave the dock, (A) the two children reach the water at the same moment and but the child who jumps forward travels farther from the dock than does the other child. (B) the child who jumps forward reaches the water before the child who jumps upward. (C) the child who jumps upward reaches the water before the child who jumps forward. (D) the two children reach the water at the same moment and at the same distance from the dock.

(B) the child who jumps forward reaches the water before the child who jumps upward.

You are visiting a playground and you notice that a girl on one swing completes each full cycle of motion in much less time than a boy on another swing. The girl has a much shorter period of motion (time to complete one full cycle) than the boy because (A) the girl is much lighter than the boy. (B) the girl is riding on a much shorter swing than the boy is riding. (C) the girl is riding on a much taller swing than the boy is riding. (D) the girl is much heavier than the boy.

(B) the girl is riding on a much shorter swing than the boy is riding.

A seemingly "haunted" house emits creaking sounds as it cools off at night. Since sound carries energy, the house must obtain that energy from somewhere (other than ghosts and goblins). While this energy begins as thermal energy, the sound doesn't appear until the outside temperature drops well below the temperature of the house because (A) the house's thermal energy increases most rapidly after dark. (B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air. (C) building materials become too soft during the day to vibrate with enough efficiency to convert thermal energy into sound energy. (D) sound, like heat, can only flow from hotter objects to colder objects.

(B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air.

A seemingly "haunted" house emits creaking sounds as it cools off at night. Since sound carries energy, the house must obtain that energy from somewhere (other than ghosts and goblins). While this energy begins as thermal energy, the sound doesn't appear until the outside temperature drops well below the temperature of the house because (A) sound, like heat, can only flow from hotter objects to colder objects. (B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air. (C) building materials become too soft during the day to vibrate with enough efficiency to convert thermal energy into sound energy. (D) the house's thermal energy increases most rapidly after dark.

(B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air.

You are using a hand-powered pump to add air to a bicycle tire. As you pump air quickly into the tire, (A) the pressure of the air in the tire increases, but the density and temperature of the air remain unchanged. (B) the pressure, density, and temperature of the air in the tire increase. (C) the pressure and temperature of the air in the tire increase, but the density of the air remains unchanged. (D) the pressure and density of the air in the tire increase, but the temperature of the air remains unchanged.

(B) the pressure, density, and temperature of the air in the tire increase.

The flow of air around a ball can be perfectly laminar only when the ball is traveling extremely slowly through the air. During such laminar flow, the ball experiences (A) both viscous drag and pressure drag. (B) pressure drag but not viscous drag. (C) viscous drag but not pressure drag. (D) neither viscous drag nor pressure drag.

(C) viscous drag but not pressure drag.

When the A-string of a guitar vibrates in its fundamental mode without anyone touching it, it has a frequency (or pitch) of 110 cycles per second. When that same string is vibrating at 330 cycles per second without anyone touching it, it is vibrating in it (A) fundamental mode, but traveling 1/3rd as far during each vibrational cycle. (B) third harmonic mode, as three 1/3rd-length strings. (C) fundamental mode, but traveling 3 times as far during each vibrational cycle. (D) fundamental mode just as before, but completing the same motion 3 times as quickly.

(B) third harmonic mode, as three 1/3rd-length strings.

You are swinging a can of paint around you in a big horizontal circle at a constant speed. You are at the center of its circular path. The net force on the paint can points directly (A) away from you. (B) toward you. (C) downward. (D) along the paint can's velocity (along its direction of travel).

(B) toward you.

The first kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes nothing at all from its environment, not even heat. An example would be a black box that consumes nothing yet provides electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of conservation of momentum. (B) violates the law of conservation of energy. (C) violates the law of thermal equilibrium. (D) violates the law of entropy.

(B) violates the law of conservation of energy.

The first kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes nothing at all from its environment, not even heat. An example would be a black box that consumes nothing yet provides electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of thermal equilibrium. (B) violates the law of conservation of energy. (C) violates the law of conservation of momentum. (D) violates the law of entropy.

(B) violates the law of conservation of energy.

The second kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes only heat from its constant-temperature environment. An example would be a black box that absorbs heat from the 70 °F room air and converts that heat into electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of thermal equilibrium. (B) violates the law of entropy. (C) violates the law of conservation of energy. (D) violates the law of conservation of momentum.

(B) violates the law of entropy.

On a humid summer day, perspiration doesn't cool you off much because (A) the air density is extremely low and its pressure is too high to permit water to evaporate. (B) water molecules land on your skin almost as often as they leave your skin, so there is almost no evaporation. (C) the water vapor in the air is moving too fast to condense on your skin as perspiration. (D) the air density is extremely low and its pressure is too low to permit water to evaporate.

(B) water molecules land on your skin almost as often as they leave your skin, so there is almost no evaporation.

You're the first person to visit Mars and you've just met a group of Martian schoolchildren. They are playing street hockey with parts from the Mars Polar Lander and, after years of watching Star Trek reruns, they are fluent in English. One of them asks you how your weight and mass have changed since you left Earth. You take a moment to measure both and reply correctly that (A) your weight is essentially unchanged but your mass is less than on Earth. (B) your mass is essentially unchanged but your weight is less than on Earth. (C) your weight and mass have both changed significantly. (D) neither your weight nor your mass have changed much.

(B) your mass is essentially unchanged but your weight is less than on Earth.

You are an astronaut floating in empty space far from Earth or anything else. You throw a wrench forward as hard as you can. While that wrench is moving forward at great speed, the net force on that wrench is (A) the force of the wrench's velocity. (B) zero. (C) the force of the wrench's momentum. (D) the force of the wrench's mass.

(B) zero.

Firefighters are battling a fire on the 12th floor of an apartment building. When they stand on the ground, their fire hose can only shoot the steady stream of water up to the 10th floor. So they carry the end of the same fire hose up a 2-story-tall ladder and shoot water upward. The other end of the hose remains attached to the same water source as before. Now the steady stream of water rises to the (A) 12th floor. (B) 8th floor. (C) 10th floor. (D) 11th floor.

(C) 10th floor.

Firefighters are battling a fire on the 12th floor of an apartment building. When they stand on the ground, their fire hose can only shoot the steady stream of water up to the 10th floor. So they carry the end of the same fire hose up a 2-story-tall ladder and shoot water upward. The other end of the hose remains attached to the same water source as before. Now the steady stream of water rises to the (A) 12th floor. (B) 6th floor. (C) 10th floor. (D) 8th floor.

(C) 10th floor.

A bottle in both thermal and phase equilibrium at 0 °C contains 1 kilogram of ice and 1 kilogram of liquid water. You move the bottle to a new location and allow it to reach equilibrium at -0.5 °C. The bottle now contains (A) 1.5 kilograms of ice and 0.5 kilograms of liquid water. (B) 0.5 kilograms of ice and 1.5 kilograms of liquid water. (C) 2 kilograms of ice. (D) 1 kilogram of ice and 1 kilogram of liquid water.

(C) 2 kilograms of ice.

Which of the following systems is definitely not a harmonic oscillator? (A) A chandelier swinging back and forth on its support cable. (B) A melon bouncing gently up and down in the basket of a grocery store spring scale. (C) A bouncy ball bouncing up and down above a granite tabletop. (D) A metal flagpole bending back and forth about its vertical equilibrium.

(C) A bouncy ball bouncing up and down above a granite tabletop.

You are rearranging the game room in your mansion and are now pushing the pool table forward across the floor. The floor is exerting a backward frictional force of 200 newtons on the table as the table moves directly forward at a constant speed. What force are you exerting on the table? (A) A forward force of more than 200 newtons. (B) You are exerting zero force on the table because the table is coasting. (C) A forward force of 200 newtons. (D) A forward force of less than 200 newtons.

(C) A forward force of 200 newtons.

You find three open mugs in the kitchen: one filled with boiling water at 212 °F (100 °C), the second filled with room temperature water at 68 °F (20 °C), and the third filled with very cold ice at 0 °F (-18 °C). Which of these mugs is releasing gaseous water molecules into the dry room air? (A) Only the room temperature water is releasing gaseous water molecules. (B) Only the boiling water and the room temperature water are releasing gaseous water molecules. (C) All three mugs are releasing gaseous water molecules. (D) Only the boiling water is releasing gaseous water molecules.

(C) All three mugs are releasing gaseous water molecules.

It is a beautiful summer day and the residents of a high-rise apartment building are eating dinner on their balconies. A resident accidentally knocks an empty glass off a balcony that is about 80 meters (260 feet) above the cement patio. The glass would have smashed on that patio after falling for 4 seconds, however, a quick-witted resident catches the glass after it has fallen for only 2 seconds. How far above the patio was the glass when it was caught? (A) Approximately 40 meters above the patio. (B) Approximately 30 meters above the patio. (C) Approximately 60 meters above the patio. (D) Approximately 50 meters above the patio.

(C) Approximately 60 meters above the patio.

It is a beautiful summer day and the residents of a high-rise apartment building are eating dinner on their balconies. A resident accidentally knocks an empty glass off a balcony that is about 80 meters (260 feet) above the cement patio. The glass would have smashed on that patio after falling for 4 seconds, however, a quick-witted resident catches the glass after it has fallen for only 2 seconds. How far above the patio was the glass when it was caught? (A) Approximately 50 meters above the patio. (B) Approximately 30 meters above the patio. (C) Approximately 60 meters above the patio. (D) Approximately 40 meters above the patio.

(C) Approximately 60 meters above the patio.

How is a steam engine able to obtain work (ordered energy) from hot steam? (A) The hot steam has a large amount of momentum and that momentum can be converted into work. (B) The steam's thermal energy can be converted into work because both are energy and energy is conserved. (C) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work. (D) The hot steam has a large amount of entropy and that entropy can be converted into work.

(C) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work.

How is a steam engine able to obtain work (ordered energy) from hot steam? (A) The hot steam has a large amount of momentum and that momentum can be converted into work. (B) The steam's thermal energy can be converted into work because both are energy and energy is conserved. (C) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work. (D) The hot steam has a large amount of entropy and that entropy can be converted into work.

(C) As heat flows from the hot steam to the colder environment, the steam engine is able to divert a fraction of that heat and convert it into work.

You fill a rubber balloon with water and use your hand to throw the balloon forward horizontally. As the balloon accelerates forward rapidly, where in the balloon is water pressure greatest? (A) At the front of the balloon (farthest from your hand). (B) At the bottom of the balloon (nearest the ground). (C) At the back of the balloon (nearest your hand). (D) At the top of the balloon (farthest from the ground).

(C) At the back of the balloon (nearest your hand).

You are flying a kite on a long string and the kite hovers motionless in the sky as the wind blows past it. The kite is high up to your east and you are pulling the kite string downward and westward. In which direction is the kite pushing on the air that passes it? (A) Upward and westward. (B) Downward and eastward. (C) Downward and westward. (D) Upward and eastward.

(C) Downward and westward.

When you pull a pendulum away from equilibrium and let go, the pendulum swings back and forth rhythmically for a very long time. What physical quantity keeps it going for so long? (A) Momentum that the pendulum cannot get rid of easily. (B) Mass that the pendulum cannot get rid of easily. (C) Energy that the pendulum cannot get rid of easily. (D) Entropy that the pendulum cannot get rid of easily.

(C) Energy that the pendulum cannot get rid of easily.

A birdfeeder hangs from a tree-branch on a long string and it can swing back and forth like a pendulum. As its birdseed is consumed, the birdfeeder's mass decreases and its center of mass moves downward. How do these two changes affect the period of the birdfeeder's swinging motion? (A) Its decrease in mass causes its period to decrease. The lowering of its center of mass causes its period to increase. (B) Its decrease in mass does not change its period. The lowering of its center of mass does not change its period. (C) Its decrease in mass does not change its period. The lowering of its center of mass causes its period to increase. (D) Its decrease in mass causes its period to decrease. The lowering of its center of mass does not change its period.

(C) Its decrease in mass does not change its period. The lowering of its center of mass causes its period to increase.

A juggler tosses a club straight up. Disregarding any effects due to the air, what force or forces are acting on the club while it is above the juggler's hands? (A) Its weight along with a steadily decreasing upward force. (B) Its weight along with an upward force that steadily decreases until the club reaches its highest point. After that point, there is only the constant downward force of gravity. (C) Its weight. (D) A steadily decreasing upward force from the moment it leaves the juggler's hands until it reaches its highest point and then a steadily increasing downward force as the club returns toward the jugglers hands.

(C) Its weight.

You remove a plastic container and its lid from the hot dishwasher. After snapping the lid on the container, you put the sealed container of air on the counter to cool. When you examine the container later, you find that its lid has bowed inward significantly, reducing the container's volume. How has the cooling process affected the air pressure and air density in the container? (A) The air's pressure has increased and its density has decreased. (B) The air's pressure has increased and its density has increased. (C) The air's pressure has decreased and its density has increased. (D) The air's pressure has decreased and its density has decreased.

(C) The air's pressure has decreased and its density has increased.

An airplane is cruising at constant velocity, 30,000 feet in the air. Which of the following correctly describes the situation above the airplane's wing? (A) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be greater than the local atmospheric pressure. (B) The airstream over the wing is traveling straight ahead, so the pressure just above the wing must equal the local atmospheric pressure. (C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (D) The airstream over the wing is bending upward, away from the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

(C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

An airplane is cruising at constant velocity, 30,000 feet in the air. Which of the following correctly describes the situation above the airplane's wing? (A) The airstream over the wing is bending upward, away from the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (B) The airstream over the wing is traveling straight ahead, so the pressure just above the wing must equal the local atmospheric pressure. (C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (D) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be greater than the local atmospheric pressure.

(C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

An airplane is cruising at constant velocity, 35,000 feet in the air. Which of the following correctly describes the situation above the airplane's wing? (A) The airstream over the wing is bending upward, away from the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (B) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be greater than the local atmospheric pressure. (C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure. (D) The airstream over the wing is traveling straight ahead, so the pressure just above the wing must equal the local atmospheric pressure.

(C) The airstream over the wing is bending downward, toward the wing, so the pressure just above the wing must be less than the local atmospheric pressure.

As an orchestra warms up, the wind instruments (e.g., flutes, clarinets, oboes) and the air inside them actually become hotter. These instruments have openings and are not sealed. How does this warming process affect the average pressure and density of the air inside the wind instruments? (A) The average pressure does not change, but the average density increases. (B) The average pressure increases, but the average density does not change. (C) The average pressure does not change, but the average density decreases. (D) The average pressure decreases, but the average density does not change.

(C) The average pressure does not change, but the average density decreases.

After John Glenn completed 3 orbits of the Earth in May 1961, it was time to return his spaceship to the ground. In which direction did rocket engines push his spaceship to cause it to descend into the atmosphere for reentry? (A) The engines pushed the spaceship forward (in the direction of its velocity). (B) The engines pushed the spaceship upward (away from the center of the Earth). (C) The engines pushed the spaceship backward (opposite its velocity). (D) The engines pushed the spaceship downward (toward the center of the Earth).

(C) The engines pushed the spaceship backward (opposite its velocity)

You add a teaspoon of salt to a glass of pure water. The salt initially sits at the bottom of the water, but it slowly dissolves so that eventually you have a glass of salt water. Which has more entropy: the glass of pure water with salt sitting at its bottom or the glass of salt water? (A) They have the same entropy because water's entropy is independent of its purity. (B) They have the same entropy because entropy is conserved. (C) The glass of salt water has more entropy. (D) The glass of pure water with salt at its bottom has more entropy.

(C) The glass of salt water has more entropy.

Winds are powered by temperature differences at the Earth's surface. As those temperature differences grow larger with climate change, the winds may also grow stronger. Why are larger temperature difference capable of producing stronger winds? (A) The greater the temperature difference, the less entropy is produced by each joule of heat that flows from hot to cold and the larger the fraction of heat that can be diverted as work. (B) The greater the temperature difference, the less entropy is produced by each joule of heat that flows from hot to cold and the more work remains available to power the winds. (C) The greater the temperature difference, the more entropy is produced by each joule of heat that flows from hot to cold and the larger the fraction of heat that can be diverted as work. (D) The greater the temperature difference, the more entropy is produced by each joule of heat that flows from hot to cold and the more of that entropy that can be converted into work.

(C) The greater the temperature difference, the more entropy is produced by each joule of heat that flows from hot to cold and the larger the fraction of heat that can be diverted as work.

Why does a paper cup of hot coffee cool so much more slowly if you cover it with a thin plastic lid? (A) The plastic lid prevents heat from flowing out through the sides of the plastic cup. (B) Plastic radiates heat much more slowly than coffee radiates heat. (C) The lid traps water vapor so that the coffee evaporates much more slowly. (D) Heat conducts through plastic much more slowly than it conducts through air.

(C) The lid traps water vapor so that the coffee evaporates much more slowly.

Two guitar strings have the same tension and the same length, but one string is more massive than the other. When you pluck them both simultaneously, how do the fundamental pitches (frequencies) of the two strings compare? (A) The more massive string has a higher pitch (larger frequency) than the less massive string. (B) The two strings have the same pitch (same frequency) because they exhibit sympathetic vibration. (C) The more massive string has a lower pitch (smaller frequency) than the less massive string. (D) The two strings have the same pitch (same frequency) because the pitch (frequency) of a harmonic oscillators is independent of mass.

(C) The more massive string has a lower pitch (smaller frequency) than the less massive string.

A mother lifts her toddler upward while that toddler clutches a toy rabbit. Who is doing work on whom? (A) There is no work being done. (B) The mother is doing work on the toddler, but there is no work done on the rabbit. (C) The mother is doing work on the toddler and the toddler is doing work on the rabbit. (D) The mother is doing work on both the toddler and on the rabbit.

(C) The mother is doing work on the toddler and the toddler is doing work on the rabbit.

You add sugar to the coffee in your mug and put the lid on. The mug is thermally insulated and sealed, so nothing goes in or out. At first, the mug contains pure coffee and undissolved sugar. Soon, the mug contains sweetened coffee and no undissolved sugar. Compare the entropies (disorders) of these two situations. (A) They have the same entropy because entropy is conserved. (B) They have the same entropy because coffee's entropy is independent of its purity. (C) The mug of sweetened coffee has more entropy. (D) The mug of pure coffee and undissolved sugar has more entropy.

(C) The mug of sweetened coffee has more entropy.

You are holding three nonflammable objects. They are identical except that one is black, one is white, and one is shiny. You place them in a roaring fire and soon they have the same temperature: 1800 °C. They remain solid. Which one is glowing most brightly? (A) The object that originally appeared white. (B) The object that originally appeared silver. (C) The object that original appeared black. (D) They are all glowing with equal brightness.

(C) The object that original appeared black.

Two identical rooms at identical temperatures contain identical collections of atoms. In one room that collection consists of moist air and a small empty cup and in the other room that collection consists of dry air and a small cup of water. Which of the two rooms has the greater entropy (disorder)? (A) The room containing dry air and the full bowl has the greater entropy. (B) The two rooms have equal entropies because they have identical temperatures. (C) The room containing moist air and an empty bowl has the greater entropy. (D) The two rooms have equal entropies because they contain identical collections of atoms.

(C) The room containing moist air and an empty bowl has the greater entropy.

While decorating your new guitar, you accidently coat one of the guitar strings with spray paint. That paint increases the string's mass. How will that change affect the string? (A) The string's frequency of vibration (pitch) will increase. (B) The string's frequency of vibration (pitch) will not change, but its amplitude of motion will increase. (C) The string's frequency of vibration (pitch) will decrease. (D) The string's frequency of vibration (pitch) will not change, but its amplitude of motion will decrease.

(C) The string's frequency of vibration (pitch) will decrease.

While decorating your new guitar, you accidently coat one of the guitar strings with spray paint. That paint increases the string's mass. How will that change affect the string? (A) The string's frequency of vibration (pitch) will not change, but its amplitude of motion will decrease. (B) The string's frequency of vibration (pitch) will not change, but its amplitude of motion will increase. (C) The string's frequency of vibration (pitch) will decrease. (D) The string's frequency of vibration (pitch) will increase.

(C) The string's frequency of vibration (pitch) will decrease.

A volleyball falls onto the ocean, where it is affected by waves traveling on the ocean's surface. If a steady pattern of wave crests is heading north at 4 mph (4 miles per hour) on a windless day, how will the floating volleyball move as it encounters this wave pattern? (A) The volleyball will move up and down, and travel northward at 4 mph. (B) The volleyball will move in a circle, and travel northward at 2 mph. (C) The volleyball will move in a circle, but make no average progress in any direction. (D) The volleyball will move up and down, and travel northward at 2 mph.

(C) The volleyball will move in a circle, but make no average progress in any direction.

Firefighters are battling a fire on the 10th floor of an apartment building. When they stand on the ground, their fire hose can only shoot the water steadily up to the 8th floor. So they carry the nozzle end of the same fire hose to the top of a 4-story-tall ladder and again point the nozzle upward. How does the speed of the water as it emerges from the nozzle near the top of the ladder compare to its speed when it emerged from the nozzle near the ground? (A) The water emerging from the nozzle near the top of the ladder travels faster. (B) The water emerges from the nozzle at the same speed in both cases. (C) The water emerging from the nozzle near the top of the ladder travels more slowly. (D) No water emerges from the nozzle when the nozzle is near the top of the ladder.

(C) The water emerging from the nozzle near the top of the ladder travels more slowly.

You are paddling a canoe across a lake. You reach forward with your paddle, lower the paddle into the water, and then pull the paddle backward toward you. The paddle, canoe, and you all accelerate forward as you pull the paddle backward. What force causes the paddle, canoe, and you to accelerate forward? (A) The water exerts a buoyant force on the paddle, pushing the paddle in the forward direction. (B) The water exerts a lift force on the paddle, pushing the paddle in the forward direction. (C) The water exerts a drag force on the paddle, pushing the paddle in the forward direction. (D) The force of the paddle's momentum pushes it in the forward direction.

(C) The water exerts a drag force on the paddle, pushing the paddle in the forward direction.

At takeoff, an airplane tilts its wings so that the leading edge (front portion of the wing) is higher than the trailing edge (back portion of the wing) and thereby obtains enough upward lift force to rise into the sky. The more aggressively it tilts its wings (the greater its angle of attack), the more lift it obtains and the faster it rises. There is a limit, however, to the rate at which the airplane can rise. If its angle of attack is too great, what happens? (A) The airplane's engines can no longer provide enough thrust to keep the plane moving forward. (B) Beyond a certain angle of attack, the lift becomes constant, regardless of the angle. (C) The wings become blunt objects and they stall (they produce large turbulent wakes). (D) The airplane completes a loop-the-loop instead of rising upward.

(C) The wings become blunt objects and they stall (they produce large turbulent wakes).

Since a water molecule weighs less than the average air molecule, humid air is less dense than dry air. Suppose that the humidity of the air increases significantly during an orchestra concert. How will the resulting decrease in air density affect the wind instruments (e.g., flutes, clarinets, oboes)? (A) Their pitches (frequencies of vibration) will decrease. (B) Their loudnesses (amplitudes of vibration) will increase. (C) Their pitches (frequencies of vibration) will increase. (D) Their loudnesses (amplitudes of vibration) will decrease.

(C) Their pitches (frequencies of vibration) will increase.

You are working at an art supply company in northern Siberia when a blizzard traps you in the unheated warehouse overnight. You are freezing and can't find a blanket anywhere. Instead, you find rolls of various materials: (a) thin, dense black paper, (b) thick, low-density black paper, (c) clear plastic sheeting, and (d) aluminum foil. To keep warmest, which pair of materials should you surround yourself with? (A) Plastic sheeting on the inside, thick black paper on the outside. (B) Thin black paper on the inside, plastic sheeting on the outside. (C) Thick black paper on the inside, aluminum foil on the outside. (D) Aluminum foil on the inside, thin black paper on the outside.

(C) Thick black paper on the inside, aluminum foil on the outside.

A music shop has numerous stringed instruments on display, including violins, guitars, and harps. You pluck the string of one instrument and it emits a tone with a frequency of 440 cycles per second (a pitch known as Concert A). When you stop that string from vibrating, you notice that other strings in the room are now vibrating at 440 cycles per second. Why did this happen? (A) Energy passed from the string you plucked to all the other strings in the room via universal energy transfer and caused them all to vibrate at 440 cycles per second. (B) The string you plucked synchronized the vibrations of all the other strings in the room so that they all vibrated together. (C) Those other strings were also tuned to vibrate at 440 cycles per second and energy was passed gradually from the string you plucked to those other strings via resonant energy transfer. (D) Your plucking motion caused all of the strings in the room to vibrate at 440 cycles per second, although not nearly as loudly as it caused your string to vibrate.

(C) Those other strings were also tuned to vibrate at 440 cycles per second and energy was passed gradually from the string you plucked to those other strings via resonant energy transfer.

A large hot air balloon drifts horizontally with the wind. What causes the balloon's velocity to change when the wind's velocity changes? [For simplicity, neglect any vertical motions of the balloon or wind.] (A) The wind exerts a buoyant force on the balloon, pushing the balloon in the direction of the wind. (B) The force of the balloon's momentum always points in the direction of the wind, so it adjusts automatically to changes in the wind. (C) Whenever the two velocities are different, the wind exerts a pressure drag force on the balloon and the balloon accelerates until its velocity is that of the wind. (D) The balloon's weight always pushes the balloon downwind, so that the balloon accelerates in the direction of the wind's velocity.

(C) Whenever the two velocities are different, the wind exerts a pressure drag force on the balloon and the balloon accelerates until its velocity is that of the wind.

As you knead bread dough, squeezing it and folding it repeatedly, the dough becomes hotter. What causes this rise in temperature? [Neglect any heat that flows between your hands and the dough due to differences in their temperatures.] (A) You are forcing convection to occur so that heat flows more rapidly through the dough. (B) You are allowing radiation to carry heat from one part of the dough to another part. (C) You are doing work on the dough and viscous effects turn that work into thermal energy in the dough. (D) You are encouraging the conduction of heat from one side of the side of the dough to the other.

(C) You are doing work on the dough and viscous effects turn that work into thermal energy in the dough.

Your coffee has cooled off and you decide to heat it the hard way: you stir the coffee vigorously for 10 minutes. The coffee does become slightly hotter. What causes this rise in temperature? (A) You are forcing convection to occur so that heat flows more rapidly from the cup to the coffee. (B) You are encouraging the conduction of heat from the cup to the coffee. (C) You do work on the coffee as you stir it and viscous effects turn that work into thermal energy. (D) You are making the coffee move as though it were boiling, so that it becomes hotter.

(C) You do work on the coffee as you stir it and viscous effects turn that work into thermal energy.

Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand removes less energy from you because it (A) pushes up on your foot just as hard as your foot pushes down on it, unlike the soft dry sand. (B) stops the downward motion of your foot faster and thus absorbs less of your momentum. (C) barely moves downward as you push downward on it, so you do almost zero work on it. (D) stops the downward motion of your foot faster and thus absorbs more of your momentum.

(C) barely moves downward as you push downward on it, so you do almost zero work on it.

If you blow across the top of a half-full bottle of water, you can produce a clear tone. If you drink some of the water and try this again, the frequency of the sound produced will (A) be the same as before your drink. (B) be smaller or larger than before your drink, depending on how much water you drank. (C) be smaller than before your drink. (D) be larger than before your drink.

(C) be smaller than before your drink.

A dog and a cat jump horizontally off a wall at the same moment and soon land on the level horizontal field that extends outward from the base of the wall. The dog weighs twice as much as the cat, but the cat was moving forward horizontally twice as fast as the dog when the two animals left the wall. In this situation, (A) the dog lands first, but both animals land at approximately the same distance from the wall. (B) both animals land at approximately the same time and at approximately the same distance from the wall. (C) both animals land at approximately the same time, but the cat lands considerably farther from the wall than the dog does. (D) the dog lands first, but the cat lands considerably farther from the wall than the dog does.

(C) both animals land at approximately the same time, but the cat lands considerably farther from the wall than the dog does.

Two cans of soup, one of which weighs twice as much as the other, roll off of a horizontal table together at the same initial velocity. In this situation, (A) both cans hit the floor at approximately the same time, but the heavier can lands considerably farther from the table than the lighter can does. (B) the heavier can hits the floor first and it lands considerably farther from the table than the lighter can does. (C) both cans hit the floor at approximately the same time and at the same distance from the table. (D) the heavier can hits the floor first and it lands considerably closer to the table than the lighter can does.

(C) both cans hit the floor at approximately the same time and at the same distance from the table.

A child is playing on a swing. As long as he doesn't swing too high, the time it takes him to complete one full oscillation will be independent of (A) the weight of the child, but not of the amplitude of the child's motion. (B) the amplitude of the child's motion, but not of the weight of the child. (C) both the amplitude of the child's motion and of the weight of the child. (D) both the length of the ropes supporting the swing and the amplitude of the child's motion.

(C) both the amplitude of the child's motion and of the weight of the child.

During the power stroke in one cylinder of a car's engine, the burned fuel and air push the piston out of the cylinder. In accordance with Newton's third law, the piston pushes back on the burned gas. Overall, the (A) burned gas does work on the piston and the gas experiences a rise in temperature. (B) piston does work on the burned gas and the gas experiences a rise in temperature. (C) burned gas does work on the piston and the gas experiences a drop in temperature. (D) piston does work on the burned gas and the gas experiences a drop in temperature.

(C) burned gas does work on the piston and the gas experiences a drop in temperature.

During the power stroke in one cylinder of a car's engine, the burned fuel and air push the piston out of the cylinder. In accordance with Newton's third law, the piston pushes back on the burned gas. Overall, the (A) piston does work on the burned gas and the gas experiences a rise in temperature. (B) piston does work on the burned gas and the gas experiences a drop in temperature. (C) burned gas does work on the piston and the gas experiences a drop in temperature. (D) burned gas does work on the piston and the gas experiences a rise in temperature.

(C) burned gas does work on the piston and the gas experiences a drop in temperature.

The air in a steam room is hotter than body temperature and it is at 100% relative humidity. If you wave your arms in the steam room, water will (A) evaporate from your arms and you will feel cooler. (B) evaporate from your arms and you will feel hotter. (C) condense on your arms and you will feel hotter. (D) condense on your arms and you will feel cooler.

(C) condense on your arms and you will feel hotter.

You can put your hand in a 400 °F (200 °C) oven briefly without getting burned. However, even a second or two of contact with 212 °F (100 °C) steam can be quite painful. The steam delivers heat much faster to your hand because steam (A) is actually a liquid with a high thermal conductivity. It is composed of countless tiny droplets suspended in the air. (B) is a gas with a much higher thermal conductivity than air. (C) condenses into water and deposits its heat of vaporization into your hand. (D) undergoes much more rapid convection than air.

(C) condenses into water and deposits its heat of vaporization into your hand.

If you blow across the top of a half-full bottle of mineral water you can produce a clear tone. If you take a drink of water to reduce the amount of liquid in the bottle and try this again, the pitch (frequency) of the sound produced will (A) increase. (B) stay the same, regardless of how hard you blow. (C) decrease. (D) stay the same, but only if you blow exactly as hard as before.

(C) decrease.

On a hot day, you drink the last drop of water in your plastic water bottle and then seal it closed. As the bottle cools off in your air conditioned car, the bottle's sides bend slightly inward so that the bottle now has slightly less volume than when you sealed it. Since you seal it, the air pressure inside the bottle has (A) stayed the same, but the density inside the bottle has increased. (B) stayed the same, but the density inside the bottle has decreased. (C) decreased and the density inside the bottle has increased. (D) decreased, but the density inside the bottle has stayed the same.

(C) decreased and the density inside the bottle has increased.

When water flows around a bend in a garden hose, the water pressure (A) decreases near the inside of the curve and decreases near the outside of the curve. (B) increases near the inside of the curve and decreases near the outside of the curve. (C) decreases near the inside of the curve and increases near the outside of the curve. (D) increases near the inside of the curve and increases near the outside of the curve.

(C) decreases near the inside of the curve and increases near the outside of the curve.

As heat flows from hot soup to a cold kitchen, the entropy (disorder) of the soup (A) decreases, the entropy of the kitchen increases, and their combined entropy remains unchanged. (B) increases, the entropy of the kitchen decreases, and their combined entropy increases. (C) decreases, the entropy of the kitchen increases, and their combined entropy increases. (D) increases, the entropy of the kitchen decreases, and their combined entropy remains unchanged.

(C) decreases, the entropy of the kitchen increases, and their combined entropy increases.

The hotter it is outside, the more electric energy an air conditioner must use to remove each joule of heat from the 72 °F indoor air in your home. It must consume more electric energy on a hotter day because (A) delivering that joule of heat to the outdoor air creates more entropy as the outdoor air gets hotter. (B) removing that joule of heat from the 72 ° indoor air creates more entropy on a hotter day. (C) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter. (D) entropy flows into your home faster when the outdoor air is hotter.

(C) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter.

To save the earth from an asteroid impact years in the future, engineers land an explosive on the asteroid and blow it to bits. Just before the detonation, the asteroid was heading directly toward mars and just after detonation, the largest piece of asteroid is heading directly toward the sun. Just after the detonation, the total momentum of all the asteroid pieces points (A) directly toward the sun. (B) in a direction between the sun and mars. (C) directly toward mars. (D) directly away from mars.

(C) directly toward mars.

A satellite is orbiting the earth in a not-quite-circular orbit. As it moves, the satellite is accelerating (A) directly outward, away from the center of the earth. (B) nearly forward, in the direction of a perfect circle around the earth. (C) directly toward the center of the earth. (D) exactly forward, in the direction that the satellite is heading.

(C) directly toward the center of the earth.

You are riding a tourist train through the hills of northern Italy. The train is currently climbing uphill at constant velocity along a train track that points directly toward a high pass between hills. The force that the train is exerting on you points (A) horizontally forward, toward the base of the hills. (B) uphill, in the direction of the train track. (C) directly upward. (D) down and forward, at right angles to the train track.

(C) directly upward.

The curator (artistic director) of a museum's gallery has laid a wool rug on a stone block and placed a copper vase on the rug. That gallery has a uniform temperature throughout, including all of the objects it contains. As a result of contact between those three objects, heat (A) flows from the copper pot to wool rug, and from the stone block to the wool rug. (B) flows from the wool rug to the copper pot, and from the wool rug to the stone block. (C) does not flow at all. (D) flows from the copper vase to wool rug, and from the wool rug to the stone block.

(C) does not flow at all.

You are riding a rollercoaster with a loop-the-loop. You have just rolled up the side of the loop and are, at this moment, exactly at the top of the loop. You and the car are upside down, yet you are pressed tightly into your seat. At this moment, you are accelerating (A) upward at a rate equal in amount to the acceleration due to gravity. (B) downward at the acceleration due to gravity. (C) downward at more than the acceleration due to gravity. (D) downward at less than the acceleration due to gravity.

(C) downward at more than the acceleration due to gravity.

A satellite is orbiting the Earth at an altitude of 100 miles. The net force on that satellite is (A) zero and it is not accelerating. (B) zero, but its velocity is changing as its path bends around the Earth. (C) equal to its weight and it is accelerating toward the center of the Earth. (D) zero, but its acceleration is changing as its path bends around the Earth.

(C) equal to its weight and it is accelerating toward the center of the Earth.

To catch a football successfully, you should allow the ball to push your hands in the direction of its travel. Allowing your hands to move with the football is crucial because it allows you to (A) add energy to the football. (B) extract momentum from the football. (C) extract energy from the football. (D) add momentum to the football.

(C) extract energy from the football.

If you kick a soccer ball straight forward at high speed with no spin at all, the air pressure at its surface will not be uniform. The location of the highest air pressure on the ball's surface will be at its (A) bottom. (B) top. (C) front (the side farthest from you). (D) back (the side nearest to you).

(C) front (the side farthest from you).

A rocket designed to put a satellite in orbit around the earth has two main tasks. First, it must lift the satellite above earth's atmosphere to eliminate air resistance. Second, it must (A) push upward on the satellite with a force that balances the satellite's downward weight so that the satellite can coast at constant velocity. (B) give the satellite such a large sideways acceleration that the satellite's apparent weight is zero. (C) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the earth rather than descending to the ground. (D) give the satellite such a large upward vertical speed that the falling satellite cannot descend to the ground.

(C) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the earth rather than descending to the ground.

Your new food-storage cooler is perfectly insulated: no heat can flow into it or out of it. You open the cooler and place a small dish of water in the cooler's warm dry air. You close the cooler. A few hours later, the cooler is full of cool moist air and the dish is empty. The cooler's overall entropy (A) has remained constant. (B) has decreased. (C) has increased. (D) may or may not have changed, depending on whether there is any water left in the cup.

(C) has increased.

Water flows gently from a kitchen faucet. You block most of the faucet's opening with your thumb and now the water sprays out at high speed because you (A) are compressing the water and increasing its density. (B) are keeping air from getting into the faucet and reducing the pressure. (C) have slowed the water flow through the faucet and plumbing. Water therefore wastes less of its total ordered energy doing work against viscous forces. (D) are doing work on the water with your thumb and greatly increasing its total ordered energy.

(C) have slowed the water flow through the faucet and plumbing. Water therefore wastes less of its total ordered energy doing work against viscous forces.

One warm spring day you and some friends go to the beach at a nearby lake. The beach ball you are playing with is not quite fully inflated, so the pressure inside it is atmospheric. Someone accidentally knocks the ball into the lake. Although it is a very hot day, the water is very cold and nobody wants to retrieve the ball. You notice that the ball seems to have deflated somewhat after sitting in the water for a while. The contact with the cool water has caused the temperature of the air inside the ball to drop, resulting in a significant (A) decrease in the density of the air inside the ball. (B) decrease in the pressure inside the ball. (C) increase in the density of the air inside the ball. (D) increase in the pressure inside the ball.

(C) increase in the density of the air inside the ball.

As air flows around a fast-moving ball, that air has difficulty maintaining laminar flow from the middle of the ball to the back of the ball. During the air's passage from the ball's middle to its back, the pressure along each streamline (A) increases and the airflow speeds up. (B) decreases and the airflow slows down. (C) increases and the airflow slows down. (D) decreases and the airflow speeds up.

(C) increases and the airflow slows down.

You are waterskiing at constant velocity behind a powerful speedboat and your arms and legs are getting tired. The net force acting on you (A) points directly forward. (B) points directly upward. (C) is zero. (D) points forward and upward.

(C) is zero.

Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand removes less energy from you because (A) it pushes up on your foot just as hard as your foot pushes on it, unlike the soft dry sand. (B) it stops the downward motion of your foot faster and thus absorbs more of your momentum. (C) it barely moves downward as you push downward on it, so you do almost zero work on it. (D) it stops the downward motion of your foot faster and thus absorbs less of your momentum.

(C) it barely moves downward as you push downward on it, so you do almost zero work on it.

The characteristic of a harmonic oscillator that makes it especially suitable for use as a timekeeper in a clock is that (A) its energy is constant, regardless of its amplitude (extent of motion). (B) its amplitude (extent of motion) is constant, regardless of its total energy. (C) its period of oscillation does not depend on its amplitude (extent of motion). (D) its momentum is constant throughout its oscillation.

(C) its period of oscillation does not depend on its amplitude (extent of motion).

The air that flows over the wing of an airplane in flight bends downward, toward the top surface of the wing. Compared to its speed and pressure before it encountered the wing, the air flowing just above the wing's top surface has a (A) smaller speed and a smaller pressure. (B) larger speed and a larger pressure. (C) larger speed and a smaller pressure. (D) smaller speed and a larger pressure.

(C) larger speed and a smaller pressure.

When you leave dry ice (solid carbon dioxide) on the kitchen counter, it gradually disappears without ever becoming liquid. If you were to examine the surface of the dry ice closely, you'd find that carbon dioxide molecules (A) become water molecules as they warm up and dissolve in the humidity. (B) leave the solid for the gas much less often than they return from the gas to the solid. (C) leave the solid for the gas much more often than they return from the gas to the solid. (D) vibrate exponentially and oscillate into dust.

(C) leave the solid for the gas much more often than they return from the gas to the solid.

When wood burns in air, the water and carbon dioxide molecules that form as the result of combustion reactions have (A) more chemical potential energy than the original wood and air molecules (B) more chemical momentum than the original wood and air molecules (C) less chemical potential energy than the original wood and air molecules (D) less chemical momentum than the original wood and air molecules

(C) less chemical potential energy than the original wood and air molecules

Your winter jacket contains 8 ounces of goose down insulation, just enough to completely fill the interior of the jacket. Suppose you open the seams and tightly pack 8 more ounces of goose down insulation into the jacket without changing its dimensions at all. After sewing up the seams, your jacket will be (A) twice as insulating as before, because goose down's thermal conductivity is proportional to one divided by its density. (B) four times as insulating as before, because goose down's thermal conductivity is proportional to one divided by the square of its density. (C) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces. (D) exactly as insulating as before because its thermal conductivity is determined only by its thickness, not by its contents.

(C) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces.

Your winter jacket contains 8 ounces of goose down insulation, just enough to completely fill the interior of the jacket. Suppose you open the seams and tightly pack 8 more ounces of goose down insulation into the jacket. After sewing up the seams, your jacket will be (A) exactly as insulating as before because its thermal conductivity is determined only by its thickness, not by its contents. (B) four times as insulating as before, because goose down's thermal conductivity is proportional to one divided by the square of its density. (C) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces. (D) twice as insulating as before, because goose down's thermal conductivity is proportional to one divided by its density.

(C) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces.

The energy needed to operate an air conditioner during the summer decreases as the outdoor temperature becomes less hot and as you adjust the thermostat to let the indoor air become less cold. The air conditioner needs less electric energy to move each joule of heat from indoor air to outdoor air because, as the temperature difference between the cool indoor air and the warm outdoor air decreases, (A) less thermal energy must become ordered energy to make up for the entropy lost when heat moves against its natural direction of flow. (B) less thermal energy must become ordered energy to make up for the entropy produced when heat moves against its natural direction of flow. (C) less ordered energy must become thermal energy to make up for the entropy lost when heat moves against its natural direction of flow. (D) less ordered energy must become thermal energy to make up for the entropy produced when heat moves against its natural direction of flow.

(C) less ordered energy must become thermal energy to make up for the entropy lost when heat moves against its natural direction of flow.

In the game of shuffleboard, you push plastic disks forward and then release them so that they slide across a level playing surface. Once you release a disk, you are no longer pushing and it gradually skids to a stop. Its final position determines your score. As each disk skids to a stop, what becomes of the kinetic energy it had when you released it? That energy is (A) now gravitational potential energy in the disk. (B) still present in the disk, as it must be because kinetic energy is conserved and can't be created or destroyed. (C) now thermal energy in the disk and playing surface. (D) now elastic potential energy in the disk.

(C) now thermal energy in the disk and playing surface.

An toddler's sipping cup has a round base (like the bottom half of a ball) that is weighed so that the cup always returns to upright after being tipped. The cup is in a stable equilibrium when it is upright and tipping it causes its total (A) kinetic energy to increase. (B) potential energy to decrease. (C) potential energy to increase. (D) kinetic energy to decrease.

(C) potential energy to increase.

During its compression stroke, a car-engine's piston squeezes the fuel and air mixture into a smaller volume within a cylinder. As the piston moves into the cylinder, the piston does work on the gas and the (A) pressure and density of gas increase, but the temperature of the gas remains unchanged. (B) density and temperature of the gas increase, but the pressure of the gas remains unchanged. (C) pressure, density, and temperature of the gas all increase. (D) pressure and temperature of the gas increase, but the density of the gas remains unchanged.

(C) pressure, density, and temperature of the gas all increase.

You are eating at an outdoor restaurant on a cold day and the restaurant has a red hot heating element positioned about 10 feet above you that keeps you surprisingly warm. Heat from that element reaches you (A) primarily via convection and conduction, with almost no heat flowing to you via radiation. (B) primarily via convection and radiation, with almost no heat flowing to you via conduction. (C) primarily via radiation, with almost no heat flowing to you via conduction or convection. (D) equally well via conduction, convection, and radiation.

(C) primarily via radiation, with almost no heat flowing to you via conduction or convection.

You are eating at an outdoor restaurant on a cold day and the restaurant has a red hot heating element positioned about 10 feet above you that keeps you surprisingly warm. Heat from that element reaches you (A) primarily via convection and conduction, with almost no heat flowing to you via radiation. (B) equally well via conduction, convection, and radiation. (C) primarily via radiation, with almost no heat flowing to you via conduction or convection. (D) primarily via convection and radiation, with almost no heat flowing to you via conduction.

(C) primarily via radiation, with almost no heat flowing to you via conduction or convection.

Tightening a guitar string (A) lowers the string's frequency or pitch by softening the string's restoring force. (B) raises the string's frequency or pitch by softening the string's restoring force. (C) raises the string's frequency or pitch by stiffening the string's restoring force. (D) lowers the string's frequency or pitch by stiffening the string's restoring force.

(C) raises the string's frequency or pitch by stiffening the string's restoring force.

Modern double-pane windows provide excellent thermal insulation. The inner surface of one of those panes is coated with a transparent electrical conductor because that coating (A) attracts gas atoms and thereby limits convective heat transfer by the argon gas trapped between the panes. (B) improves the thermal conductivity of the coated pane and helps keep it at the same temperature as the other pane. (C) reflects infrared light and blocks radiative heat transfer from one pane to the other. (D) prevents the argon gas atoms from transferring heat via conduction to the coated pane.

(C) reflects infrared light and blocks radiative heat transfer from one pane to the other.

A helium-filled balloon weighs only about 1/7th as much as the air it displaces. If you replace the helium gas in the balloon with hydrogen gas (which is half as dense as helium gas), the upward buoyant force on the balloon would (A) increase and the net force on the balloon would approximately double in the upward direction. (B) increase and the net force on the balloon would increase slightly in the upward direction. (C) stay the same and the net force on the balloon would increase slightly in the upward direction. (D) decrease and the net force on the balloon would approximately double in the upward direction.

(C) stay the same and the net force on the balloon would increase slightly in the upward direction.

Moments before it's ignited by the sparkplug, the mixture of fuel and air inside an automobile engine cylinder is compressed to very high density. During the compression process, the mixture's (A) temperature stays the same but its pressure rises. (B) temperature rises dramatically but its pressure drops. (C) temperature rises dramatically and so does its pressure. (D) temperature drops dramatically but its pressure rises.

(C) temperature rises dramatically and so does its pressure.

You are a famous stylist, putting the finishing touches on Lady Gaga's hair before her performance. Alas, your bottle of signature hair goo is almost empty! You put the cap on the bottle and swing it rapidly in a circle with its cap end pointing outward. The remaining hair goo collects just inside the cap and you are able to extract enough to complete your work. This technique works because (A) viscous forces push the hair goo toward the cap end of the bottle. (B) centrifugal force pushes the hair goo toward the cap end of the bottle. (C) the bottle's rapid inward acceleration leaves the hair goo behind so that it drifts toward the cap end of the bottle. (D) the force of the hair goo's momentum pushes it toward the cap end of the bottle.

(C) the bottle's rapid inward acceleration leaves the hair goo behind so that it drifts toward the cap end of the bottle.

If you hold a full glass bottle of root beer in your hand and pound the top of that bottle with a rubber mallet, (A) the top of the bottle will be knocked off. (B) the sides of the bottle will be blown outward. (C) the bottom of the bottle will be knocked out. (D) the neck of the bottle will compress smoothly into the body of the bottle without breaking the glass.

(C) the bottom of the bottle will be knocked out.

Two squirrels are fighting over a tasty acorn. Each squirrel is pulling on one side of the acorn and they are not making any progress. At last, the female squirrel holds her side of the acorn motionless as the male squirrel tears his half of the acorn away. Tearing the acorn in half required energy and that energy was provided by (A) both squirrels. (B) neither squirrel. It was instead provided by chemical potential energy in the acorn itself. (C) the male squirrel. (D) the female squirrel.

(C) the male squirrel.

When you pull a tablecloth out from under a set of dishes, it's important to pull the cloth as fast as possible because (A) the force of sliding friction that the cloth exerts on the dishes is proportional to the time during which the cloth is moving. (B) the work done on the dishes by the cloth is proportional to the time during which the cloth pulls on them. (C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them. (D) the weight of the dishes on the cloth is proportional to the time during which the cloth is moving.

(C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them.

When a cylinder in an automobile's engine is going through the power stroke, the hot burned gas is pushing the piston out of the cylinder. As the piston moves out of the cylinder, the burned gas does work on the piston and (A) the pressure of the burned gas remains constant while the temperature of the burned gas decreases. (B) the pressure and temperature of the burned gas both remain constant. (C) the pressure and temperature of the burned gas both decrease. (D) the pressure of the burned gas decreases while the temperature of the burned gas remains constant.

(C) the pressure and temperature of the burned gas both decrease.

In Charlottesville, water boils at approximately 100 °C (212 °F). In the Blue Ridge Mountains, however, water boils at about 97 °C (207 °F) because (A) 97 °C in the mountains is actually the same temperature as 100 °C in Charlottesville. (B) the greater altitude in the mountains gives water molecules farther to fall after they break free of the water's surface as steam. (C) the reduced atmospheric pressure in the mountains allows steam bubbles in the water to grow by evaporation at that lower temperature. (D) the weaker gravity in the mountains allows water molecules to move faster at that lower temperature.

(C) the reduced atmospheric pressure in the mountains allows steam bubbles in the water to grow by evaporation at that lower temperature.

A dozen houses have just been built on a steep hillside overlooking a beautiful lake. A simple water distribution system provides water to all of those houses; they share a single delivery pipe with a branch for each house. Residents at various altitudes above the lake begin taking showers and have different experiences. They observe that the total ordered energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) greater at higher altitudes. (B) the same on all altitudes, but the speed of the spraying water is greater at higher altitudes. (C) the same at all altitudes, but the speed of the spraying water is smaller at higher altitudes. (D) smaller at higher altitudes.

(C) the same at all altitudes, but the speed of the spraying water is smaller at higher altitudes.

The second kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes only heat from its constant-temperature environment. An example would be a black box that absorbs heat from the 70 °F room air and converts that heat into electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of conservation of momentum. (B) violates the law of thermal equilibrium. (C) violates the law of entropy. (D) violates the law of conservation of energy.

(C) violates the law of entropy.

Because of bad planning during the design and construction of a high-rise apartment building, all 50 floors of the building receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) the same on all floors, but the speed of the spraying water is greater on higher floors. (B) smaller on higher floors (C) the same on all floors, but the speed of the spraying water is smaller on higher floors. (D) greater on higher floors.

(C) the same on all floors, but the speed of the spraying water is smaller on higher floors.

You are already in the shower when you discover your tube of shampoo is almost empty. To get the last few drops of shampoo, you swing the tube rapidly in a circle with the cap-end of the tube pointing away from you. This technique works because (A) the force of the shampoo's momentum pushes it toward the cap-end of the tube. (B) viscous forces push the shampoo toward the cap-end of the tube. (C) the tube's rapid inward acceleration leaves the shampoo behind so that the shampoo drifts toward the cap-end of the tube. (D) centrifugal force pushes the shampoo toward the cap-end of the tube.

(C) the tube's rapid inward acceleration leaves the shampoo behind so that the shampoo drifts toward the cap-end of the tube.

Two toy cars roll off a level table side-by-side at the same time and in the same direction. The cars soon hit the level floor below the table. The cars have identical weights, but the violet car was traveling twice as fast as the yellow car when they left the table. In this situation, (A) the violet car hits the floor much sooner than the yellow car, but the violet car hits considerably farther from the table than the yellow car. (B) the yellow car hits the floor much sooner than the violet car, but the violet car hits considerably farther from the table than the yellow car. (C) the two cars hit the floor at approximately the same time, but the violet car hits considerably farther from the table than the yellow car. (D) the two cars hit the floor at approximately the same time and the same distance from the table.

(C) the two cars hit the floor at approximately the same time, but the violet car hits considerably farther from the table than the yellow car.

You are inflating a shiny plastic balloon with helium. The balloon starts as a thin, flat bag but it gradually gets thicker as it fills. At first, the thin plastic balloon doesn't float. But as you keep adding helium to the balloon and it gets thicker, it eventually begins floating because (A) the helium-filled balloon's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (B) the average pressure of the helium-filled balloon increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (C) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight. (D) the upward buoyant force on a balloon full of helium is larger than the buoyant force on an identical balloon full of air.

(C) the weight of the helium-filled balloon increases as it fills, but the buoyant force it experiences increases much faster and eventually the buoyant force exceeds the balloon's weight.

When the A-string of a guitar vibrates in its fundamental mode without anyone touching it, it has a frequency (or pitch) of 110 cycles per second. When that same string is vibrating at 330 cycles per second without anyone touching it, it is vibrating in its (A) fundamental mode just as before, but completing the same motion 3 times as quickly. (B) fundamental mode, but traveling 3 times as far during each vibrational cycle. (C) third harmonic mode, as three 1/3rd-length strings. (D) fundamental mode, but traveling 1/3rd as far during each vibrational cycle.

(C) third harmonic mode, as three 1/3rd-length strings.

Compared to an ordinary surface wave on the ocean, a tsunami has a much longer wavelength and therefore (A) travels much slower and has much higher pressure at the surface of the water. (B) travels much slower and has much lower pressure at the surface of the water. (C) travels much faster and involves water that is much deeper into the ocean. (D) travels much faster and has its adjacent crests spaced much closer together.

(C) travels much faster and involves water that is much deeper into the ocean.

The first kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes nothing at all from its environment, not even heat. An example would be a black box that consumes nothing yet provides electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of thermal equilibrium. (B) violates the law of conservation of momentum. (C) violates the law of conservation of energy. (D) violates the law of entropy.

(C) violates the law of conservation of energy.

When you pour milk from a pitcher into a bowl, the flow is likely to become turbulent. When you pour honey from a jar into a bowl, however, the flow is likely to remain laminar. Compared to milk, honey is more likely to exhibit laminar flow because honey's larger (A) weight tends to keep the flow orderly. (B) density tends to keep the flow orderly. (C) viscosity tends to keep the flow orderly. (D) inertia tends to keep the flow orderly.

(C) viscosity tends to keep the flow orderly.

You are jogging on a hot, humid summer day and are covered with perspiration. Unfortunately, that perspiration doesn't cool you off much because (A) the air pressure is too high to permit water to evaporate quickly. (B) the air density is too low to permit water to evaporate quickly. (C) water molecules are landing from the air onto your perspiration almost as often as they are leaving your perspiration for the air. (D) the air density is too high to permit water to evaporate quickly.

(C) water molecules are landing from the air onto your perspiration almost as often as they are leaving your perspiration for the air.

When you stand in front of an open refrigerator, trying to decide which flavor of Ben and Jerry's to eat, you feel cold even though no chilled air actually touches your skin. The reason you feel cold is that (A) the cold refrigerator is radiating cold toward you and is lowering the temperature of your skin directly. (B) you can sense the presence of nearby cold air, even though it is not exchanging cold with your skin. (C) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return. (D) you can sense the presence of nearby cold air, even though it is not exchanging heat with your skin.

(C) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return.

Even though your Thanksgiving dinner consists of a tofu turkey, you discover that it contains a wishbone. You and your cousin decide to break the wishbone; the one with the large half gets their wish. Your cousin holds one end of the wishbone motionless as you pull the other end toward you rapidly. The wishbone snaps and you're left holding only a tiny fragment. Better luck next time! Breaking the wishbone required energy and that energy was provided by (A) neither of you. It was instead provided by chemical potential energy in the wishbone itself. (B) your cousin. (C) you. (D) both you and your cousin.

(C) you.

Even though your Thanksgiving dinner consists of a tofu turkey, you discover that it contains a wishbone. You and your cousin decide to break the wishbone; the one with the large half gets their wish. Your cousin holds one end of the wishbone motionless as you pull the other end toward you rapidly. The wishbone snaps and you're left holding only a tiny fragment. Better luck next time! Breaking the wishbone required energy and that energy was provided by (A) your cousin. (B) neither of you. It was instead provided by chemical potential energy in the wishbone itself. (C) you. (D) both you and your cousin.

(C) you.

A skateboarder is being pulled up a gradual hill by a bicyclist and they are both moving at constant velocity. The net force on the skateboarder is (A) directed downhill and the net force on the bicyclist is directed uphill. (B) directed uphill and the net force on the bicyclist is directed downhill. (C) zero and the net force on the bicyclist is zero. (D) directed uphill and the net force on the bicyclist is directed uphill.

(C) zero and the net force on the bicyclist is zero.

You are an astronaut floating in empty space far from Earth or anything else. You throw a video camera forward as hard as you can. While that camera is moving forward at great speed, the net force on that camera is (A) the force of the camera's momentum. (B) the force of the camera's mass. (C) zero. (D) the force of the camera's velocity.

(C) zero.

You are pulling your niece uphill on a sled and the sled experiences a small downhill frictional force as it slides uphill on the snow. Your niece is traveling in a straight line at a constant speed. The net force your niece is experiencing is (A) in the uphill direction. (B) in the downhill direction. (C) zero. (D) in the upward direction.

(C) zero.

A bottle in thermal equilibrium at 0 °C (32 °F) contains 1 kilogram of ice and 1 kilogram of liquid water. You move the bottle to a new location and allow it to reach thermal equilibrium at +0.5 °C. The bottle now contains (A) 0.5 kilograms of ice and 1.5 kilograms of liquid water. (B) 2 kilograms of ice. (C) 1.5 kilograms of ice and 0.5 kilograms of liquid water. (D) 2 kilograms of liquid water.

(D) 2 kilograms of liquid water.

Firefighters are battling a fire on the 10th floor of an apartment building. When they stand on the ground, their fire hose can only shoot the steady stream of water up to the 8th floor. So they carry the end of the same fire hose up a 2-story-tall ladder and shoot water upward. The other end of the hose remains attached to the same water source as before. Now the steady stream of water rises to the (A) 9th floor. (B) 6th floor. (C) 10th floor. (D) 8th floor.

(D) 8th floor.

Firefighters are battling a fire on the 10th floor of an apartment building. When they stand on the ground, water flowing through their firehose from their firetruck can only shoot the water up to the 8th floor. So they carry the end of the same fire hose up a 2-story-tall ladder and again start shooting water upward. Now the water rises to the (A) 6th floor. (B) 10th floor. (C) 9th floor. (D) 8th floor.

(D) 8th floor.

You are trying to set the world's record for drinking water through the tallest drinking straw. What could you do to have the best chance of setting this record? (A) Use the narrowest drinking straw you can find. (B) Use the widest drinking straw you can fit in your mouth. (C) Choose a bad-weather day when the atmospheric pressure is as small as possible. (D) Choose a good-weather day when the atmospheric pressure is as large as possible.

(D) Choose a good-weather day when the atmospheric pressure is as large as possible.

An automobile engine "knocks" when the gaseous fuel-air mixture in its cylinder ignites spontaneously rather than waiting for the sparkplug to ignite it. What causes that premature ignition of the fuel-air mixture? (A) Entropy in the fuel-air mixture becomes thermal energy and ignites the mixture. (B) Heat flowing into the fuel-air mixture from the engine's walls ignites the mixture. (C) Expansion of the fuel-air mixture causes its temperature to surge upward so that it ignites. (D) Compression of the fuel-air mixture causes its temperature to surge upward so that it ignites.

(D) Compression of the fuel-air mixture causes its temperature to surge upward so that it ignites.

It's a stormy day, and you're struggling to hold your umbrella steady. The wind is blowing toward the east and your motionless umbrella is pulling your hands upward and eastward. In which direction is the umbrella pushing on the air that passes it? (A) Upward and westward. (B) Downward and eastward. (C) Upward and eastward. (D) Downward and westward.

(D) Downward and westward.

Why must a sprinter lean forward as she picks up speed at the start of a race? (A) She must lean in the direction of her velocity in order to increase that forward velocity. (B) By leaning forward, she can use her weight to make her accelerate forward at the acceleration due to gravity. (C) Her forward lean moves her closer to the finish line so that she arrives sooner. (D) If she stood upright as the ground pushed her feet forward, the inertia of her upper body would cause her to tip over backward.

(D) If she stood upright as the ground pushed her feet forward, the inertia of her upper body would cause her to tip over backward.

You string a zip-line (a taut metal cable) from the balcony of your mansion to the stables 500 meters away. A small trolley allows you to glide down that cable to visit your horses. On a windy day, you notice that the cable is vibrating slightly in its fundamental vibrational mode with a period (time to complete 1 full cycle of motion) of 1 second. What could you do to the cable to decrease (shorten) that period? (A) Decrease the cable's tension, decrease the cable's mass, or shorten the cable. (B) Increase the cable's tension, increase the cable's mass, or shorten the cable. (C) Decrease the cable's tension, decrease the cable's mass, or lengthen the cable. (D) Increase the cable's tension, decrease the cable's mass, or shorten the cable.

(D) Increase the cable's tension, decrease the cable's mass, or shorten the cable.

Mike and Johnny are in trouble for scuffling in the school cafeteria. While Mike admits that he pushed Johnny, who immediately fell over backward, Mike claims that Johnny pushed back and is thus just as guilty. From the perspective of physics, (A) Johnny pushed back on Mike, but with more force than Mike exerted on him. (B) Johnny pushed back on Mike, but with less force than Mike exerted on him. (C) Johnny didn't push back on Mike. (D) Johnny did push back on Mike, with exactly the same amount of force.

(D) Johnny did push back on Mike, with exactly the same amount of force.

A typical heat pump (an air conditioner run backwards so that it heats the indoor air) consumes 1000 watts of electric power. How much thermal power does it deliver to the indoor air? (A) About 900 watts. (B) About 1000 watts. (C) About 100 watts. (D) Significantly more than 1000 watts.

(D) Significantly more than 1000 watts.

A typical heat pump (an air conditioner run backwards so that it heats the indoor air) consumes 2000 watts of electric power. How much thermal power does it provide to the indoor air? (A) About 200 watts. (B) About 2000 watts. (C) About 1800 watts. (D) Significantly more than 2000 watts.

(D) Significantly more than 2000 watts.

If you're designing an energy efficient automobile, why should you minimize the diameter of the turbulent wake it leaves behind in the air? (A) Since air in the wake has higher than atmospheric pressure, having less air in the wake means less pressure pushing on the rear of the car. (B) Since air in the wake has higher than atmospheric density, having less air in the wake means less inertia to overcome. (C) Since the automobile exhaust heats air in the wake, having less air in the wake means less heat extracted from the car. (D) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted forward momentum.

(D) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted forward momentum.

If you're designing an energy efficient automobile, why should you minimize the diameter of the turbulent wake it leaves behind in the air? (A) Since the automobile exhaust heats air in the wake, having less air in the wake means less heat extracted from the car. (B) Since air in the wake has higher than atmospheric pressure, having less air in the wake means less pressure pushing on the rear of the car. (C) Since air in the wake has higher than atmospheric density, having less air in the wake means less inertia to overcome. (D) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted momentum.

(D) Since air in the wake has extracted forward momentum from the car, having less air in the wake means less extracted momentum.

A child is using a crayon (a stick of colored wax) to draw a picture on a sheet of paper. The paper rests on a horizontal tabletop and the child's crayon is moving across the paper at a steady speed in a straight line. Which of the following statements about the forces acting on the crayon is correct? (A) If the child were to exert twice as much force on the crayon, the crayon would slide across the paper at twice its original speed. (B) The amount of the force the child is exerting on the crayon must be more than the amount of the force that friction is exerting on the crayon. (C) The amount of the force the child is exerting on the crayon must be more than the amount of the crayon's weight. (D) The amount of the force the child is exerting on the crayon must be equal to the amount of force that friction is exerting on the crayon.

(D) The amount of the force the child is exerting on the crayon must be equal to the amount of force that friction is exerting on the crayon.

An automobile engine "knocks" when the gas in its cylinder ignites spontaneously rather than waiting for the sparkplug to ignite it. During which of the 4 strokes can this premature ignition occur? (A) The intake stroke (when gas is being added to the cylinder). (B) The power stroke (when the gas in the cylinder is pushing the piston out of the cylinder). (C) The exhaust stroke (when gas is being ejected from the cylinder). (D) The compression stroke (when the gas in the cylinder is being compressed).

(D) The compression stroke (when the gas in the cylinder is being compressed).

It's a hot summer day and you turn on the air conditioner to cool your room. As the air conditioner operates, what happens to the energy in the indoor air, the outdoor air, and at the electric company? [Note: the electric company's energy changes when you consume electric power.] (A) The energies of the outdoor air and the electric company decrease, and the energy of the indoor air increases. (B) The energies of the indoor air and the outdoor air increase, and the energy of the electric company decreases. (C) The energies of the indoor air and the outdoor air decrease, and the energy of the electric company increases. (D) The energies of the indoor air and the electric company decrease, and the energy of the outdoor air increases.

(D) The energies of the indoor air and the electric company decrease, and the energy of the outdoor air increases.

As a window air conditioner cools the air in your room on a hot summer day, which of the following statements about energy and entropy is correct? (A) The energy in the room air is decreasing, but the entropy in the room air is increasing. (B) The room air's energy is becoming entropy while the outdoor air's entropy is becoming energy. (C) The total energy in the room air and the outdoor air is constant, but the total entropy in the room air and the outdoor air is increasing. (D) The energy and entropy in the room air are decreasing and the energy and entropy in the outdoor air are increasing.

(D) The energy and entropy in the room air are decreasing and the energy and entropy in the outdoor air are increasing.

You are rearranging your room and are now sliding your desk across the floor at constant velocity. Which of the following statements about the forces acting on the desk is correct? [Consider only horizontal forces.] (A) The amount of force that you're exerting on the desk must be equal to the amount of its weight. (B) The amount of force that you're exerting on the desk must be more than the amount of its weight. (C) The amount of force that you're exerting on the desk must be more than the amount of force that friction is exerting on it. (D) The force that you're exerting on the desk must be equal in amount but opposite in direction to the force that the floor is exerting on it.

(D) The force that you're exerting on the desk must be equal in amount but opposite in direction to the force that the floor is exerting on it.

In its fundamental vibrational mode, a guitar string vibrates as a single string. In its second harmonic mode, the string vibrates as two half-strings. How do those two vibrations differ? (A) The amplitude and loudness of the second harmonic mode is half that of the fundamental mode. (B) The frequency (number of vibrational cycles per second) of the second harmonic mode is half that of the fundamental mode. (C) The amplitude and loudness of the second harmonic mode is twice that of the fundamental mode. (D) The frequency (number of vibrational cycles per second) of the second harmonic mode is twice that of the fundamental mode.

(D) The frequency (number of vibrational cycles per second) of the second harmonic mode is twice that of the fundamental mode.

You add a teaspoon of salt to a glass of pure water. The salt initially sits at the bottom of the water, but it slowly dissolves so that eventually you have a glass of salt water. Which has more entropy: the glass of pure water with salt sitting at its bottom or the glass of salt water? (A) They have the same entropy because entropy is conserved. (B) They have the same entropy because water's entropy is independent of its purity. (C) The glass of pure water with salt at its bottom has more entropy. (D) The glass of salt water has more entropy.

(D) The glass of salt water has more entropy.

Suppose a musician is playing a wind instrument (e.g., a flute, clarinet, or oboe) and the density of the air suddenly decreases. There is no change in the air's pressure or in how the musician is playing the instrument. What happens to the instrument's sound? (A) The instrument's volume (amplitude) increases. (B) The instrument's pitch (frequency) decreases. (C) The instrument's volume (amplitude) decreases. (D) The instrument's pitch (frequency) increases.

(D) The instrument's pitch (frequency) increases.

You forgot to tip the bartender who brought a Shirley Temple drink to your luxury hotel suite. So you're leaning out over the balcony of your 20th floor suite and dropping solid gold marbles into the tip jar on the ground floor patio bar. You notice that it takes 4 seconds for each marble to fall into the jar, 20 floors below. When each marble has fallen for only 2 seconds, which floor of the hotel is it nearest? [Note: neglect any effects due to the air.] (A) The marble is near the 8th floor. (B) The marble is near the 12th floor. (C) The marble is near the 10th floor. (D) The marble is near the 15th floor.

(D) The marble is near the 15th floor.

The three nonflammable objects in your hand are identical except that one is black, one is white, and one is shiny. You place them in a roaring fire and soon they have the same temperature: 1800 °C. They remain solid. Which one is glowing most brightly? (A) The object that originally appeared white. (B) The object that originally appeared silver. (C) They are all glowing with equal brightness. (D) The object that original appeared black.

(D) The object that original appeared black.

The three nonflammable objects in your hand are identical except that one is black, one is white, and one is shiny. You place them in a roaring fire and soon they have the same temperature: 1800 °C. They remain solid. Which one is glowing most brightly? (A) They are all glowing with equal brightness. (B) The object that originally appeared shiny. (C) The object that originally appeared white. (D) The object that original appeared black.

(D) The object that original appeared black.

The three nonflammable objects in your hand are identical except that one is black, one is white, and one is shiny. You place them in a roaring fire and soon they have the same temperature: 1800 °C. They remain solid. Which one is glowing most brightly? (A) They are all glowing with equal brightness. (B) The object that originally appeared white. (C) The object that originally appeared silver. (D) The object that original appeared black.

(D) The object that original appeared black.

An air conditioner's compressor takes low density gas and compresses that gas to high density and that gas begins to condense into a liquid. Why does compressing the gas cause it to condense? (A) Compression removes entropy from the gas so that has to become a liquid. (B) Compression causes the temperature of the gas to decrease so that it condenses into a liquid. (C) Increasing the density of the gas removes its latent heat of evaporation and forces it to become a liquid. (D) The rate at which molecules land on the liquid from the gas exceeds the rate at which molecules leave the liquid for the gas.

(D) The rate at which molecules land on the liquid from the gas exceeds the rate at which molecules leave the liquid for the gas.

Two identical rooms at identical temperatures contain identical collections of atoms. In one room that collection consists of a block of salt and a basin of fresh water. In the other room that collection consists of a basin of salt water. Which of the two rooms has the greater entropy (disorder)? (A) The two rooms have equal entropies because they contain identical collections of atoms. (B) The two rooms have equal entropies because they have identical temperatures. (C) The room containing the block of salt and the basin of fresh water has the greater entropy. (D) The room containing the salt water has the greater entropy.

(D) The room containing the salt water has the greater entropy.

You are designing clothing and equipment that will help a downhill ski racer to win her races. Why should you minimize the size of the turbulent wake the skier produces in the air behind her? (A) The skier gives mass to the wake in order to make it turbulent, so having less air in the wake means retaining as much mass as possible. (B) The skier exerts a backward force on the wake in order to make it turbulent and that backward force slows the skier's forward velocity. The smaller the wake, the smaller the force. (C) The wake shifts the skier's center of gravity backward, making it harder for her to accelerate forward. The smaller the wake, the smaller the shift and the faster the skier can move. (D) The skier gives forward momentum to the wake, so having less air in the wake means giving away less forward momentum.

(D) The skier gives forward momentum to the wake, so having less air in the wake means giving away less forward momentum.

If you pluck a guitar string at different points along its length, it will produce somewhat different sounds. What is different about the string when you pluck it at different points? (A) The string's fundamental vibrational frequency depends on where you plucking it. (B) The string's fundamental vibrational frequency depends on its amplitude of vibration and that amplitude depends on where you pluck the string. (C) Where you pluck the string divides the string into two parts that vibrate separately, so where you pluck affects those two partial strings. (D) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it.

(D) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it.

You're eating lunch outdoors on a hot day and half the ice in your glass of water has melted since you started eating. How has the temperature of the water in your glass changed over that period? (A) The temperature of the water has increased by 8 °F. (B) The temperature of the water has increased by 4 °F. (C) The temperature of the water has increased by 2 °F. (D) The temperature of the water has remained constant.

(D) The temperature of the water has remained constant.

Since a water molecule weighs less than the average air molecule, humid air is less dense than dry air. Suppose that the humidity of the air increases significantly during an orchestra concert. How will the resulting decrease in air density affect the wind instruments (e.g., flutes, clarinets, oboes)? (A) Their pitches (frequencies of vibration) will decrease. (B) Their loudnesses (amplitudes of vibration) will increase. (C) Their loudnesses (amplitudes of vibration) will decrease. (D) Their pitches (frequencies of vibration) will increase.

(D) Their pitches (frequencies of vibration) will increase.

To save the earth from an asteroid impact years in the future, engineers land an explosive on the asteroid and blow it to bits. Just before the detonation, the asteroid was heading directly toward mars and just after detonation, the largest piece of asteroid is heading directly toward the sun. Just after the detonation, the total momentum of all the asteroid pieces points (A) directly away from mars. (B) directly toward the sun. (C) in a direction between the sun and mars. (D) directly toward mars.

(D) directly toward mars.

You have a large block of slippery ice in the back of your pickup truck. As the truck turns toward the left at high speed, the block of ice slides up against the right side of the truck bed. What force, if any, is pushing the ice toward the right? (A) A support force from the truck bed is pushing the ice toward the right. (B) The force of the ice's momentum is pushing it toward the right. (C) A friction force from the truck bed is pushing the ice toward the right. (D) There is no force pushing the ice toward the right.

(D) There is no force pushing the ice toward the right.

A common type of water pump produces pressurized water by spinning a cylindrical volume of water rapidly about its center. Water enters the pump where the water pressure is smallest and leaves the pump where the water pressure is greatest. Where on the cylinder of water does the water enter and leave the pump? (A) Water enters and leaves at the cylinder's outer edge, but the water completes one full rotation between entering and leaving. (B) Water enters at the cylinder's outer edge and leaves at the cylinder's center. (C) Water enters and leaves at the cylinder's outer edge, but on opposite sides of the cylinder. (D) Water enters at the cylinder's center and leaves at the cylinder's outer edge.

(D) Water enters at the cylinder's center and leaves at the cylinder's outer edge.

Your coffee has cooled off and you decide to heat it the hard way: you stir the coffee vigorously for 10 minutes. The coffee does become slightly hotter. What causes this rise in temperature? (A) You are making the coffee move as though it were boiling, so that it becomes hotter. (B) You are encouraging the conduction of heat from the cup to the coffee. (C) You are forcing convection to occur so that heat flows more rapidly from the cup to the coffee. (D) You do work on the coffee as you stir it and viscous effects turn that work into thermal energy.

(D) You do work on the coffee as you stir it and viscous effects turn that work into thermal energy.

A hot air balloon is passing over your head when the pilot turns on the flame and heats up the air inside the balloon's envelope (the balloon's fabric skin). That envelope is open at the bottom, where the flame heats it. As the temperature of the air inside the unsealed envelope increases, the (A) air molecules flow into the envelope's opening and the density of the air inside the envelope increases. (B) upward buoyant force on the balloon increases and it begins to rise. (C) air molecules flow into the envelope's opening and the pressure of the air inside the envelope increases. (D) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

(D) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

During your ride in a hot air balloon, the pilot turns on the flame to heat up the air inside the balloon's envelope (the balloon's fabric skin). That envelope is open at the bottom, where the flame heats it. As the temperature of the air inside the unsealed envelope increases, (A) the upward buoyant force on the balloon increases and it begins to rise. (B) air molecules flow into the envelope's opening and the pressure of the air inside the envelope increases. (C) air molecules flow into the envelope's opening and the density of the air inside the envelope increases. (D) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

(D) air molecules flow out of the envelope's opening and the weight of the air inside the envelope decreases.

After a volleyball is served and is heading through the air and over the net, it gradually slows down. The primary reason for this slowing is that the air pressure (A) at the front of the ball is equal to atmospheric pressure, while the pressure behind the ball is less than atmospheric. (B) at the front and back of the ball is greater than atmospheric pressure, while the pressure on the sides of the ball is less than atmospheric. (C) at the front and back of the ball is less than atmospheric pressure, while the pressure on the sides of the ball is more than atmospheric. (D) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric.

(D) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric.

Once a baseball leaves the pitcher's hand and is heading toward home plate, it gradually slows down. The primary reason for this slowing is that the air pressure (A) at the front and back of the ball is less than atmospheric pressure, while the pressure on the sides of the ball is more than atmospheric. (B) at the front and back of the ball is greater than atmospheric pressure, while the pressure on the sides of the ball is less than atmospheric. (C) at the front of the ball is equal to atmospheric pressure, while the pressure behind the ball is less than atmospheric. (D) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric.

(D) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric.

Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand removes less energy from you because it (A) stops the downward motion of your foot faster and thus absorbs more of your momentum. (B) stops the downward motion of your foot faster and thus absorbs less of your momentum. (C) pushes up on your foot just as hard as your foot pushes down on it, unlike the soft dry sand. (D) barely moves downward as you push downward on it, so you do almost zero work on it.

(D) barely moves downward as you push downward on it, so you do almost zero work on it.

Two steel balls, one of which weighs twice as much as the other, roll off a horizontal table with the same speeds. In this situation, (A) the heavier ball hits the floor at about half the horizontal distance from the base of the table than does the lighter. (B) the lighter ball hits the floor at about half the horizontal distance from the base of the table than does the heavier. (C) the heavier ball hits considerably closer to the base of the table than the lighter, but not necessarily half the horizontal distance. (D) both balls hits the floor at approximately the same horizontal distance from the base of the table.

(D) both balls hits the floor at approximately the same horizontal distance from the base of the table.

Two bars of soap slide off of a horizontal counter at the same time, side by side. The green bar of soap weighs twice as much as the orange bar of soap, but the orange bar has twice the velocity of the green bar when the two first lose contact with the counter. In this situation, (A) the green bar hits the floor first, but the two bars land at about the same distance from the counter. (B) both bars hit the floor at approximately the same time, but the green bar lands considerably farther from the counter than the orange bar does. (C) the green bar hits the floor first and it lands considerably closer to the counter than the orange bar does. (D) both bars hit the floor at approximately the same time, but the orange bar lands considerably farther from the counter than the green bar does.

(D) both bars hit the floor at approximately the same time, but the orange bar lands considerably farther from the counter than the green bar does.

Liquid water can coexist with ice at 0 °C. If you dissolve sugar in the water, it (A) can coexist with ice at a temperature greater than 0 °C. (B) cannot coexist with ice at any temperature. (C) can coexist with ice at 0 °C. (D) can coexist with ice at a temperature less than 0 °C.

(D) can coexist with ice at a temperature less than 0 °C.

If you try to cook vegetables with 100 °C air, it takes a long time. But if you cook those same vegetables with 100 °C steam, they cook quickly. This is because the steam (A) causes moisture inside the vegetables to boil and transfer heat to the vegetables. (B) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. (C) causes moisture inside the vegetables to boil and absorb heat from the vegetables. (D) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

(D) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

Most electric power generating stations use steam to generate electricity. These stations all have cooling towers or other devices for getting rid of waste heat. There is no way to operate a steam-powered generating station without sending waste heat into the environment because (A) heat always flows from hotter to colder objects. (B) entropy is conserved. (C) energy is always increasing. (D) converting all of the heat into work would violate the law of entropy.

(D) converting all of the heat into work would violate the law of entropy.

When water rushing through a fire hose flows around a bend in that hose, its pressure changes. The water pressure (A) decreases near the inside of the bend and decreases near the outside of the bend. (B) increases near the inside of the bend and increases near the outside of the bend. (C) increases near the inside of the bend and decreases near the outside of the bend. (D) decreases near the inside of the bend and increases near the outside of the bend.

(D) decreases near the inside of the bend and increases near the outside of the bend.

When water rushing through a hose flows around a bend in that hose, its pressure changes. The water pressure (A) increases near the inside of the bend and increases near the outside of the bend. (B) increases near the inside of the bend and decreases near the outside of the bend. (C) decreases near the inside of the bend and decreases near the outside of the bend. (D) decreases near the inside of the bend and increases near the outside of the bend.

(D) decreases near the inside of the bend and increases near the outside of the bend.

When water flows around a bend in a garden hose, the water pressure (A) increases near the inside of the curve and increases near the outside of the curve. (B) decreases near the inside of the curve and decreases near the outside of the curve. (C) increases near the inside of the curve and decreases near the outside of the curve. (D) decreases near the inside of the curve and increases near the outside of the curve.

(D) decreases near the inside of the curve and increases near the outside of the curve.

The hotter the outdoor air, the more electric energy an air conditioner must use to remove each joule of heat from the 72 °F indoor air in your home. The air conditioner must consume more electric energy on a hotter day because (A) entropy flows into your home faster when the outdoor air is hotter. (B) heat flows into your home faster when the outdoor air is hotter. (C) delivering each joule of heat to the outdoor air produces more entropy as the outdoor air gets hotter. (D) delivering each joule of heat to the outdoor air produces less entropy as the outdoor air gets hotter.

(D) delivering each joule of heat to the outdoor air produces less entropy as the outdoor air gets hotter.

The plumbing in a new high-rise hotel was carefully designed so that the water pressure is exactly the same on all floors and the bathroom showers spray exactly the same on all floors. Neglecting any effects due to viscosity or friction, the total ordered energy (the sum of gravitational potential energy, pressure potential energy, and kinetic energy) per liter of water is (A) the same on different floors and the sum of pressure potential energy and kinetic energy per liter is the same on different floors. (B) the same on different floors and the sum of pressure potential energy and kinetic energy per liter is different on different floors. (C) different on different floors and the sum of pressure potential energy and kinetic energy per liter is different on different floors. (D) different on different floors, but the sum of pressure potential energy and kinetic energy per liter is the same on different floors.

(D) different on different floors, but the sum of pressure potential energy and kinetic energy per liter is the same on different floors.

A gust of wind shakes your home and causes a hanging chandelier to begin swinging gently back and forth on its support chain. When its overall motion is small, the time it takes the chandelier to complete one full oscillation of that motion (its period of oscillation) does not depend on (A) the chandelier's amplitude of motion, but it does depend on the chandelier's weight. (B) the length of the chain supporting the chandelier. (C) the chandelier's weight, but it does depend on the chandelier's amplitude of motion. (D) either the chandelier's weight or the chandelier's amplitude of motion.

(D) either the chandelier's weight or the chandelier's amplitude of motion.

An automobile's internal combustion engine burns a mixture of fuel and air in its cylinders. It is impossible for this engine to convert all of the chemical potential energy of the fuel and air mixture into mechanical work because burning that mixture increases its (A) energy. (B) momentum. (C) pressure. (D) entropy.

(D) entropy.

An astronaut is orbiting the Earth inside the International Space Station and she is hovering in the middle of the cabin. The net force on that astronaut is (A) zero and she is not accelerating. (B) zero, but her velocity is changing as her path bends around the Earth. (C) zero, but her acceleration is changing as her path bends around the Earth. (D) equal to her weight and she is accelerating downward (toward the center of the Earth).

(D) equal to her weight and she is accelerating downward (toward the center of the Earth).

Water is flowing through a horizontal pipe in laminar, steady-state flow. Halfway along the pipe, its diameter decreases and the water must continue on through that narrow second half. Compared to when it was in the wide first half of the pipe, water in the narrow second half of the pipe is moving (A) slower and its pressure is smaller. (B) faster and its pressure is larger. (C) slower and its pressure is larger. (D) faster and its pressure is smaller.

(D) faster and its pressure is smaller.

A rocket designed to put a satellite in orbit around the earth has two main tasks. First, it must lift the satellite above earth's atmosphere to eliminate air resistance. Second, it must (A) give the satellite such a large upward vertical speed that the falling satellite cannot descend to the ground. (B) push upward on the satellite with a force that balances the satellite's downward weight so that the satellite can coast at constant velocity. (C) give the satellite such a large sideways acceleration that the satellite's apparent weight is zero. (D) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the earth rather than descending to the ground.

(D) give the satellite such a large horizontal speed that the falling satellite arcs endlessly around the earth rather than descending to the ground.

A space tourism company offers to carry people to orbit in a luxurious spaceship. To perform that task, the ship's rocket engines must lift the ship above Earth's atmosphere and (A) give the ship such a large upward vertical speed that the falling ship cannot descend to the ground. (B) push upward on the ship with a force that balances the ship's downward weight so that the ship can coast at constant velocity. (C) give the ship such a large downward acceleration that the ship's apparent weight is zero. (D) give the ship such a large horizontal speed that the falling ship arcs endlessly around the Earth rather than descending to the ground.

(D) give the ship such a large horizontal speed that the falling ship arcs endlessly around the Earth rather than descending to the ground.

When you jump while standing on a bathroom scale, it briefly reads more than your actual weight. During that moment, it is exerting an upward force on you that is (A) equal to your weight and you are accelerating upward. (B) equal to your weight and your velocity is constant. (C) greater than your weight and your velocity is constant. (D) greater than your weight and you are accelerating upward.

(D) greater than your weight and you are accelerating upward.

You're drinking a cup of hot coffee in an airplane at 35,000 feet. Suddenly the airplane pressurization system fails and the cabin's air pressure decreases abruptly. The coffee begins to boil because its temperature (A) has suddenly decreased. (B) hasn't changed but the air bubbles inside it have suddenly expanded. (C) has suddenly increased. (D) hasn't changed but bubbles of pure steam are now stable inside it.

(D) hasn't changed but bubbles of pure steam are now stable inside it.

Water is flowing gently out of the end of a garden hose. You block off most of the hose's opening with your thumb and now the water sprays out at high speed because you (A) are keeping air from getting into the hose, where it would reduce the water pressure. (B) are compressing the water and increasing its density. (C) are doing work on the water with your thumb and greatly increasing its total energy. (D) have slowed the water flow through hose and plumbing so that the water wastes less ordered energy doing work against viscous forces.

(D) have slowed the water flow through hose and plumbing so that the water wastes less ordered energy doing work against viscous forces.

It's a warm summer day and you and your friends are drinking root beers on the lawn outside your dorm. You decide to move the refrigerator out of the air-conditioned dorm and onto the lawn. As the result of this move, the refrigerator consumes more electric power because (A) the lawn is farther from the electric outlet. (B) the refrigerator becomes less efficient at pumping heat, even though the rate at which heat leaks into the refrigerator remains unchanged. (C) heat leaks into the refrigerator more rapidly, even though the refrigerator's efficiency remains unchanged. (D) heat leaks into the refrigerator more rapidly and because the refrigerator becomes less efficient at pumping heat.

(D) heat leaks into the refrigerator more rapidly and because the refrigerator becomes less efficient at pumping heat.

As it flies horizontally over the net, a volleyball experiences pressure drag because the air pressure (A) in front of the ball is lower than the air pressure behind it. (B) below the ball is higher than the air pressure above the ball. (C) around the ball is uniform everywhere. (D) in front of the ball is higher than the air pressure behind it.

(D) in front of the ball is higher than the air pressure behind it.

At high altitude, a commercial jetliner must compress the outside air before circulating it in the pressurized cabin. The compressed air must first be sent through an air conditioner, however, because compressing air (A) turns it into a liquid and the air conditioner's evaporator allows it to return to a gas. (B) decreases its humidity. (C) increases its humidity. (D) increases its temperature.

(D) increases its temperature.

Increasing the amount of carbon dioxide (a greenhouse gas) in the earth's atmosphere (A) increases the rate at which the earth radiates heat into space. (B) decreases the rate at which the earth radiates heat into space. (C) has no effect on the earth's thermal radiation or the effective surface that emits that thermal radiation. (D) increases the altitude of the earth's effective radiating surface.

(D) increases the altitude of the earth's effective radiating surface.

Increasing the amount of carbon dioxide (a greenhouse gas) in the earth's atmosphere (A) increases the rate at which the earth radiates heat into space. (B) has no effect on the earth's thermal radiation or the effective surface that emits that thermal radiation. (C) decreases the rate at which the earth radiates heat into space. (D) increases the altitude of the earth's effective radiating surface.

(D) increases the altitude of the earth's effective radiating surface.

A satellite is traveling around the earth in a circular orbit. It briefly fires its rocket engine to increase its speed in the forward direction; it is suddenly going faster but its direction of travel didn't change. As a result of this speed increase, the orbiting satellite's average distance from the center of the earth (A) remains unchanged, but the orbit is no longer circular. (B) decreases. (C) remains unchanged and the orbit continues to be circular. (D) increases.

(D) increases.

A car drives over a fire hydrant and breaks it off at ground level. A fountain of water rises upward into the open air. As that rising water's gravitational potential energy increases, (A) its pressure potential energy decreases, but its kinetic energy remains constant. (B) neither its pressure potential energy nor its kinetic energy change. (C) both its pressure potential energy and its kinetic energy decrease. (D) its kinetic energy decreases, but its pressure potential energy remains constant.

(D) its kinetic energy decreases, but its pressure potential energy remains constant.

You are standing in a slow-moving stream, facing upstream so that the water is coming toward the front of your body. You are wearing shorts and the water level is slightly above your bare knees. The water experiences perfect laminar flow around each of your nearly cylindrical legs. You measure the water pressure at a specific altitude below your right knee and find that the water pressure is (A) largest on the front of your leg, medium on the sides of your leg, and smallest on the back of your leg. (B) the same all the way around your leg, since you are measuring the pressure at constant altitude. (C) smallest on the front of your leg, largest on the sides of your leg, and medium on the back of your leg. (D) largest on the front and back of your leg and smallest on the sides of your leg.

(D) largest on the front and back of your leg and smallest on the sides of your leg.

Your winter jacket contains 8 ounces of goose down insulation, just enough to completely fill the interior of the jacket. Suppose you open the seams and tightly pack 8 more ounces of goose down insulation into the jacket. After sewing up the seams, your jacket will be (A) twice as insulating as before, because goose down's thermal conductivity is proportional to one divided by its density. (B) exactly as insulating as before because its thermal conductivity is determined only by its thickness, not by its contents. (C) four times as insulating as before, because goose down's thermal conductivity is proportional to one divided by the square of its density. (D) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces.

(D) less insulating than before, because the excess goose down conducts heat better than the trapped air it replaces.

Your luxury apartment has a dining room table that is so enormous, it has a "lazy Susan" in the middle. This large circular platform rotates frictionlessly so that you can "pass" the marmalade jar to your guests by placing that jar on the platform and then rotating the platform. When you replace the empty jar with a full jar from the pantry, the full jar definitely (A) increases the platform's angular velocity. (B) decreases the platform's angular velocity. (C) makes it easier to change the platform's angular velocity. (D) makes it harder to change the platform's angular velocity.

(D) makes it harder to change the platform's angular velocity.

Water hammer occurs when you suddenly stop the rapid flow of water in a pipe and results in the pipe-end experience a huge force in the direction of the water's original motion. It happens because flowing water has (A) acceleration. (B) energy. (C) angular momentum. (D) momentum.

(D) momentum.

When a log is floating on water, much of the log is above the water and is actually surrounded by air. If that surrounding air were to disappear suddenly, the log would (A) sink to the bottom of the water. (B) move upward slightly and float somewhat higher (less deep) in the water. (C) float at the same height as before the air left. (D) move downward slightly and float somewhat lower (deeper) in the water.

(D) move downward slightly and float somewhat lower (deeper) in the water.

Your glass of water has one cube of ice floating at the water's surface. Part of the cube is above the water. Olive oil is less dense than water. When you pour a layer of chilled olive oil onto the water's surface, the ice cube (A) floats at the same height so that the same amount of the cube is above the water as before. (B) moves downward so that less of the cube is above the water. (C) sinks to the bottom of the water. (D) moves upward so that more of the cube is above the water.

(D) moves upward so that more of the cube is above the water.

Near sea level, water normally boils at about 212 °F (100 °C). However, a microwave oven can heat water in a glass container above that temperature if (A) the glass container does not conduct electricity. (B) the water is very pure. (C) the glass container remains colder than 212 °F (100 °C). (D) nothing helps form the initial steam bubbles.

(D) nothing helps form the initial steam bubbles.

Near sea level, water normally boils at about 212 °F (100 °C). However, a microwave oven can heat water in a glass container above that temperature if (A) the glass container remains colder than 212 °F (100 °C). (B) the glass container does not conduct electricity. (C) the water is very pure. (D) nothing helps form the initial steam bubbles.

(D) nothing helps form the initial steam bubbles.

Two puppies are fighting over a toy. Each puppy grips one end of that toy in its mouth and pulls. Suddenly, the puppy on the right pulls especially hard on the toy and moves its end of the toy to the right. The other puppy manages to keep its end of the toy from moving. Alas, the toy breaks and the game ends. Breaking the toy required energy and that energy was provided (A) by both puppies, but most was provided by the puppy on the right. (B) in equal amounts by the two puppies. (C) only by the puppy on the left. (D) only by the puppy on the right.

(D) only by the puppy on the right.

When you ride a bicycle, the ground exerts an upward support force on the wheel. When you turn the bicycle, the ground also exerts a horizontal frictional force on the wheel that causes you to accelerate sideways. Leaning the bicycle toward the inside of a turn keeps you from flipping over because the overall force that the ground exerts on the wheel (A) points exactly at right angles to your combined center of mass and exerts a torque on you that keeps you from falling over. (B) is exactly zero and causes no acceleration of your combined center of mass. (C) points directly upward so that you don't fall downward. (D) points directly toward your combined center of mass and produces zero torque.

(D) points directly toward your combined center of mass and produces zero torque.

You are on the outdoor deck of a restaurant, watching athletes compete in winter sports. The weather is cold, but the red-hot heating element positioned about 10 feet above you keeps you surprisingly warm. Heat from that element reaches you (A) primarily via convection and conduction, with almost no heat flowing to you via radiation. (B) equally well via conduction, convection, and radiation. (C) primarily via convection and radiation, with almost no heat flowing to you via conduction. (D) primarily via radiation, with almost no heat flowing to you via conduction or convection.

(D) primarily via radiation, with almost no heat flowing to you via conduction or convection.

It's a cold day and you have run out of wood for your fireplace. You place an electric hotplate in the fireplace and turn it on. For safety, you open the chimney flue to let air above the hot plate flow up the chimney and out of the house. The hotplate glows red hot. Heat will flow from the hotplate to people sitting across the room from the fireplace (A) primarily via convection and radiation, with almost no heat flowing via conduction. (B) equally poorly via conduction, convection, and radiation, and those people will feel cold. (C) equally well via conduction, convection, and radiation, and those people will feel warm. (D) primarily via radiation, with almost no heat flowing via conduction or convection.

(D) primarily via radiation, with almost no heat flowing via conduction or convection.

To win a stuffed animal at the state fair, you simply need to drop a glass marble onto a stationary glass plate and have the marble come to rest on that plate. Unfortunately, when the marble hits the plate, it bounces upward because the marble (A) retains essentially all of its energy and momentum. (B) transfers a large amount of momentum and energy to the plate. (C) retains essentially all of its momentum but transfers a large amount of energy to the plate. (D) retains essentially all of its energy but transfers a large amount of momentum to the plate.

(D) retains essentially all of its energy but transfers a large amount of momentum to the plate.

Just mixing gasoline and air together won't make them burst into flames because (A) their densities must be increased considerably before they will ignite. (B) they must be compressed into liquid before they can burn. (C) their velocities must be increased considerably before they will ignite. (D) something must provide the activation energy needed to initiate the chemical reaction.

(D) something must provide the activation energy needed to initiate the chemical reaction.

Just mixing gasoline and air together won't make them burst into flames because (A) their densities must be increased considerably before they will ignite. (B) they must be compressed into liquid before they can burn. (C) their velocities must be increased considerably before they will ignite. (D) something must provide the activation energy needed to initiate the chemical reaction.

(D) something must provide the activation energy needed to initiate the chemical reaction.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) pressure. (B) viscosity or its density. (C) speed or its viscosity. (D) speed or its density.

(D) speed or its density.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) viscosity. (B) pressure. (C) transparency. (D) speed.

(D) speed.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) pressure. (B) transparency. (C) viscosity. (D) speed.

(D) speed.

An airplane is cruising horizontally at 30,000 feet and is traveling at constant velocity. The overall force that airplane exerts on the air points (A) straight backward (toward the rear of the plane). (B) downward and backward (toward the rear of the plane). (C) downward and forward (toward the front of the plane). (D) straight downward.

(D) straight downward.

Your French fries are getting cold as you wait for your server to bring you a new bottle of ketchup. In frustration, you decide to get the last bits of ketchup out of the old bottle by swinging it rapidly in a circle with the cap-end of the bottle pointing away from you. This technique works because (A) the force of the ketchup's momentum pushes it toward the cap-end of the bottle. (B) centrifugal force pushes the ketchup toward the cap-end of the bottle. (C) viscous forces push the ketchup toward the cap-end of the bottle. (D) the bottle's rapid inward acceleration leaves the ketchup behind so that it drifts toward the cap-end of the bottle.

(D) the bottle's rapid inward acceleration leaves the ketchup behind so that it drifts toward the cap-end of the bottle.

You have forgotten to buy more shampoo and there is only a tiny bit left in your old bottle. To move that shampoo toward the opening of the bottle, you swinging the bottle rapidly in a circle with its cap-end pointing away from the center of the circle. This technique works because (A) centrifugal force pushes the shampoo toward the cap-end of the bottle. (B) viscous forces push the shampoo toward the cap-end of the bottle. (C) the force of the shampoo 's momentum pushes it toward the cap-end of the bottle. (D) the bottle's rapid inward acceleration leaves the shampoo behind so that it moves toward the cap-end of the bottle.

(D) the bottle's rapid inward acceleration leaves the shampoo behind so that it moves toward the cap-end of the bottle.

You are visiting a playground and you notice that a girl on one swing completes each full cycle of motion in much less time than a boy on another swing. The girl has a much shorter period of motion (time between cycles) than the boy because (A) the girl is much lighter than the boy. (B) the girl is riding on a much taller swing than the boy is riding. (C) the girl is much heavier than the boy. (D) the girl is riding on a much shorter swing than the boy is riding.

(D) the girl is riding on a much shorter swing than the boy is riding.

You are visiting a playground and you notice that a girl on one swing completes each full cycle of motion in much less time than a boy on another swing. The girl has a much shorter period of motion (time between cycles) than the boy because (A) the girl is much lighter than the boy. (B) the girl is riding on a much taller swing than the boy is riding. (C) the girl is much heavier than the boy. (D) the girl is riding on a much shorter swing than the boy is riding.

(D) the girl is riding on a much shorter swing than the boy is riding.

You're at the lake and watch two children jump off a dock. They jump at the same time and at the same speed, but the boy jumps mostly upward while the girl jumps mostly forward. After they leave the dock, (A) the two children reach the water at the same moment and at the same distance from the dock. (B) the two children reach the water at the same moment and but the girl travels farther from the dock than does the boy. (C) the boy reaches the water before the girl. (D) the girl reaches the water before the boy.

(D) the girl reaches the water before the boy.

A seemingly "haunted" house emits creaking sounds as it cools off at night. Since sound carries energy, the house must obtain that energy from somewhere (other than ghosts and goblins). While this energy begins as thermal energy, the sound doesn't appear until the outside temperature drops well below the temperature of the house because (A) building materials become too soft during the day to vibrate with enough efficiency to convert thermal energy into sound energy. (B) sound, like heat, can only flow from hotter objects to colder objects. (C) the house's thermal energy increases most rapidly after dark. (D) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air.

(D) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air.

You are using a hand-powered pump to add air to a bicycle tire. As you pump air quickly into the tire, (A) the pressure of the air in the tire increases, but the density and temperature of the air remain unchanged. (B) the pressure and temperature of the air in the tire increase, but the density of the air remains unchanged. (C) the pressure and density of the air in the tire increase, but the temperature of the air remains unchanged. (D) the pressure, density, and temperature of the air in the tire increase.

(D) the pressure, density, and temperature of the air in the tire increase.

As you sit in a restaurant, you tap your wineglass with your fork and it emits a loud tone. A wineglass elsewhere on the table starts to vibrate even though you never touched it directly. The pitch emitted by the second wineglass is (A) twice the pitch of your wineglass. (B) slightly lower than the pitch of your wineglass. (C) slightly higher than the pitch of your wineglass. (D) the same as the pitch of your wineglass.

(D) the same as the pitch of your wineglass.

You take off your shoes to sneak quietly into your home late at night. Unfortunately, it's too dark to see the concrete block your friend left on the floor and your big toe collides with it. The block doesn't move and your foot comes to a complete stop due to the impact. Luckily, you are wearing soft woolen socks because when your foot stops during the impact, your toe transfers (A) less energy to the block than it would have if you had not been wearing socks. (B) less momentum to the block than it would have if you had not been wearing socks. (C) less velocity to the block than it would have if you had not been wearing socks. (D) the same momentum, whether or not you are wearing socks, but that transfer takes more time when you are wearing socks.

(D) the same momentum, whether or not you are wearing socks, but that transfer takes more time when you are wearing socks.

A builder outsourced the design and construction of a high-rise apartment building, as a result, all 50 floors receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) smaller on higher floors. (B) greater on higher floors. (C) the same on all floors, but the speed of the spraying water is greater on higher floors. (D) the same on all floors, but the speed of the spraying water is smaller on higher floors.

(D) the same on all floors, but the speed of the spraying water is smaller on higher floors.

Because of bad planning during the design and construction of a high-rise apartment building, all 50 floors of the building receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) smaller on higher floors. (B) the same on all floors, but the speed of the spraying water is greater on higher floors. (C) greater on higher floors. (D) the same on all floors, but the speed of the spraying water is smaller on higher floors.

(D) the same on all floors, but the speed of the spraying water is smaller on higher floors.

A huge abstract iron sculpture has been installed in front of the local art museum. It sits there motionless, "guarding" the main doorway. The sculpture is experiencing two forces: its weight downward and a force upward from the brick courtyard beneath it. We know that these two forces on the sculpture are equal in amount but oppositely directed because (A) the sculpture has zero velocity. (B) Newton's third law requires that forces always appear in equal but oppositely directed pairs. (C) for every action, there is an equal but oppositely directed reaction. (D) the sculpture is not accelerating, so the two forces must sum to zero.

(D) the sculpture is not accelerating, so the two forces must sum to zero.

Your friend puts an open container of vegetable soup in a frost-free freezer and lets it freeze solid. He then forgets about it for more than year. We he rediscovers the open container, he finds it almost empty except for the vegetables because (A) the soup has melted periodically and some of it has dripped into the bottom of the freezer. (B) the greedy vegetables drank the soup. (C) the soup has melted periodically and some of it has evaporated before it could refreeze. (D) the soup's water molecules have gone directly from solid ice to gaseous water vapor.

(D) the soup's water molecules have gone directly from solid ice to gaseous water vapor.

You can add a thickening agent to soup to make that soup much more viscous without changing its density. You are stirring two pots of soup, one without the thickener and one with the thickener, using identical spoons. You find that (A) stirring speed has no effect because both pots of soup remain laminar at all speeds. (B) the thickened soup becomes turbulent at a lower stirring speed than the unthickened soup. (C) the two pots of soup become turbulent at approximately the same stirring speed. (D) the unthickened soup becomes turbulent at a lower stirring speed than the thickened soup.

(D) the unthickened soup becomes turbulent at a lower stirring speed than the thickened soup.

A child is riding on a playground merry-go-round (a horizontal platform that rotates about a fixed center). As the merry-go-round rotates at a steady rate, the net force on the child points directly (A) along the child's velocity (along the child's direction of travel). (B) downward. (C) away from the center of the merry-go-round. (D) toward the center of the merry-go-round.

(D) toward the center of the merry-go-round.

The second kind of perpetual motion machine provides an inexhaustible supply of mechanical work (or the equivalent of work), but consumes only heat from its constant-temperature environment. An example would be a black box that absorbs heat from the 70 °F room air and converts that heat into electricity forever. This form of perpetual motion machine is impossible because it (A) violates the law of conservation of energy. (B) violates the law of thermal equilibrium. (C) violates the law of conservation of momentum. (D) violates the law of entropy.

(D) violates the law of entropy.

Ice cubes gradually shrink in a frost-free freezer because (A) the ice melts periodically and some of it evaporates before it can refreeze. (B) the ice melts periodically and some of it drips into the bottom of the freezer. (C) the freezer mice like to nibble on the ice cubes. (D) water molecules go directly from solid ice to gaseous water vapor.

(D) water molecules go directly from solid ice to gaseous water vapor.

You accidently leave the lid off a container of peach sorbet when you place it in a frost-free freezer. Peach sorbet is sugar, water, and peach juice that have been frozen into tiny particles of peach ice. Six months later, you retrieve the container and find it almost empty because (A) the peach ice has melted periodically and some of it has evaporated before it could refreeze. (B) the peach ice has melted periodically and some of it has dripped into the bottom of the freezer. (C) the freezer gremlins like to nibble on the peach sorbet. (D) water molecules have gone directly from solid ice to gaseous water vapor.

(D) water molecules have gone directly from solid ice to gaseous water vapor.

If you pluck a guitar string at different points along its length, it will produce somewhat different sounds. What is different about the string when you pluck it at different points? (A) The string's fundamental vibrational frequency depends on its amplitude of vibration and that amplitude depends on where you pluck the string. (B) Where you pluck the string divides the string into two parts that vibrate separately, so where you pluck affects those two partial strings. (C) The string's fundamental vibrational frequency depends on where you plucking it. (D) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it.

.(D) The string can vibrate simultaneously in its fundamental and harmonic vibrational modes, and the mixture of those different vibrations depends on where you pluck it.

When a liquid flows through a collection of stationary obstacles, its flow can be smooth and laminar, or it can be swirling and turbulent. The liquid's flow is more likely to become turbulent if you increase its (A) speed or its density. (B) pressure. (C) speed or its viscosity. (D) viscosity or its density.

(A) speed or its density.

You are moving into a loft apartment and are now dragging an old carpet across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the carpet is correct? (A) The amount of force that you're exerting on the carpet must be equal to the amount of force that friction is exerting on it. (B) The amount of force that you're exerting on the carpet must be more than the amount of force that friction is exerting on it. (C) The amount of force that you're exerting on the carpet must be more than the amount of its weight. (D) If you were to exert twice as much force on the carpet, it would slide across the floor twice as fast.

(A) The amount of force that you're exerting on the carpet must be equal to amount of force that friction is exerting on it.

If you try to cook vegetables with 100 °C air, it takes a long time. But if you cook those same vegetables with 100 °C steam, they cook quickly. This is because the steam (A) condenses on the colder vegetables and releases a large amount of heat to the vegetables. (B) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. (C) causes moisture inside the vegetables to boil and transfer heat to the vegetables. (D) causes moisture inside the vegetables to boil and absorb heat from the vegetables.

(A) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

If you blow carefully across the top of a drinking straw, it will emit a tone. If you now close off the bottom of the straw with your finger, the tone that it emits will (A) go down by an octave (its frequency will decrease by a factor of 2). (B) stay the same. (C) go down by a fifth (its frequency will decrease by a factor of 1.5). (D) go up by an octave (its frequency will increase by a factor of 2).

(A) go down by an octave (its frequency will decrease by a factor of 2).

One warm spring day you and some friends go to the beach at a nearby lake. You are playing with an almost fully inflated beach ball, which has a limp, floppy skin that dents effortlessly when you push on it. Someone accidentally throws the ball it into the ice cold lake. The ball appears to deflate partly on contact with the freezing water, although it has no leak. The large decrease in the ball's temperature caused a large (A) increase in the density of the air inside the ball. (B) increase in the pressure of the air inside the ball. (C) decrease in the pressure of the air inside the ball. (D) decrease in the density of the air inside the ball.

(A) increase in the density of the air inside the ball.

One warm spring day you and some friends go to the beach at a nearby lake. You are tossing a soft, almost fully inflated beach ball around when someone accidentally knocks it into the lake. Although it is a very hot day, the water is very cold and nobody wants to retrieve the ball. You notice that the ball seems to have deflated somewhat after sitting in the water for a while. The contact with the cool water has caused the temperature of the air inside the ball to drop, resulting in a significant (A) increase in the density of the air inside the ball. (B) increase in the pressure inside the ball. (C) decrease in the pressure inside the ball. (D) decrease in the density of the air inside the ball.

(A) increase in the density of the air inside the ball.

You throw a curve ball that is bending toward your right as it travels away from you. It is able to bend in this manner because (A) it is deflecting the airflow around it toward your left. (B) the pressure in front of it is higher than the pressure behind it. (C) you gave it a rightward push as it came out of your fingers. (D) it is deflecting the airflow around it toward your right as well.

(A) it is deflecting the airflow around it toward your left.

Once water is heated to 100 °C (212 °F) at sea level, (A) it usually begins to boil, but it requires additional energy to convert from a liquid to a gas without changing temperature. (B) water molecules first begin to leave the water's surface as a gas. (C) it usually begins to boil, but its requires additional energy to convert from a liquid to a gas because it must change temperature to undergo the change of phase. (D) it immediately turns to steam without the further introduction of energy.

(A) it usually begins to boil, but it requires additional energy to convert from a liquid to a gas without changing temperature.

When an airplane is in level flight at 30,000 feet and moving at constant velocity, the average air pressure just above its wings is (A) less than atmospheric pressure and the average air pressure just below its wings is more than atmospheric pressure. (B) more than atmospheric pressure and the average air pressure just below its wings is less than atmospheric pressure. (C) less than atmospheric pressure and the average air pressure just below its wings is less than atmospheric pressure. (D) more than atmospheric pressure and the average air pressure just below its wings is more than atmospheric pressure.

(A) less than atmospheric pressure and the average air pressure just below its wings is more than atmospheric pressure.

You are in the kitchen with three mixing bowls in front of you. One bowl is metal, the second is glass, and the third is plastic. All three are at exactly the same temperature. If you touch the three bowls together, (A) no heat will flow between the bowls. (B) heat will flow from the plastic bowl to the glass bowl, and from the glass bowl to the metal bowl. (C) heat will flow from the glass bowl to both the plastic bowl and the metal bowl. (D) heat will flow from the metal bowl to the glass bowl, and from the glass bowl to the plastic bowl.

(A) no heat will flow between the bowls.

You are out for a bicycle ride on a calm, windless day. You are heading northward on a level road and are experiencing a pressure drag force that pushes you toward the south. This air resistance explains why you have to keep pedaling to maintain your constant speed. If someone were to examine the air that you have left behind you after you have passed through it, they would find that the air's average velocity is (A) northward. (B) zero and that it is calm. (C) zero but that it is swirling rapidly in all directions. (D) southward.

(A) northward.

If you increase the length of the pendulum in your grandfather clock, which previously kept excellent time, you will discover that the clock is (A) running slow (the clock's minute hand takes more than 60 minutes to complete a full rotation). (B) still keeping excellent time because the period of oscillation of a pendulum depends only on the weight of the pendulum and the strength of gravity. (C) running fast (the clock's minute hand takes less than 60 minutes to complete a full rotation). (D) still keeping excellent time because the period of oscillation of a pendulum depends only on the mass of the pendulum and the strength of gravity.

(A) running slow (the clock's minute hand takes more than 60 minutes to complete a full rotation).

A helium-filled balloon weighs only about 1/7th as much as the air it displaces. If you replace the helium gas in the balloon with hydrogen gas (which is half as dense as helium gas), the upward buoyant force on the balloon would (A) stay the same and the net force on the balloon would increase slightly in the upward direction. (B) increase and the net force on the balloon would increase slightly in the upward direction. (C) decrease and the net force on the balloon would roughly double in the upward direction. (D) increase and the net force on the balloon would roughly double in the upward direction.

(A) stay the same and the net force on the balloon would increase slightly in the upward direction.

A chandelier hangs motionless from the ceiling. The amount of momentum that chandelier is transferring to the ceiling each second is (A) the chandelier's weight times 1 second. (B) the chandelier's weight divided by the chandelier's mass. (C) zero. (D) the chandelier's mass times 1 second.

(A) the chandelier's weight times 1 second.

When you stand in front of an open refrigerator, trying to decide which flavor of Ben and Jerry's to eat, you feel cold even though no chilled air actually touches your skin. The reason you feel cold is that (A) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return. (B) you can sense the presence of nearby cold air, even though it is not exchanging cold with your skin. (C) you can sense the presence of nearby cold air, even though it is not exchanging heat with your skin. (D) the cold refrigerator is radiating cold toward you and is lowering the temperature of your skin directly.

(A) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return.

A toy top is spinning steadily on a table, with only its sharp point touching the table's surface. What is keeping it spinning? (A) A torque about its center of mass, produced by the support force that the table exerts on the top's point. (B) No torque at all, just its own angular momentum. (C) A torque about its axis of rotation, produced by the force of friction on the top's point. (D) A torque about the top's point, produced by the top's weight.

(B) No torque at all, just its own angular momentum.

You are dragging an old carpet across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the carpet is correct? (A) The amount of force that you're exerting on the carpet must be more than the amount of force that friction is exerting on it. (B) The amount of force that you're exerting on the carpet must be equal to the amount of force that friction is exerting on it. (C) The amount of force that you're exerting on the carpet must be more than the amount of its weight. (D) If you were to exert twice as much force on the carpet, it would slide across the floor twice as fast.

(B) The amount of force that you're exerting on the carpet must be equal to the amount of force that friction is exerting on it.

You are pushing a file cabinet across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the file cabinet is correct? (A) The amount of the force that you're exerting on the file cabinet must be more than the amount of its weight. (B) The amount of the force that you're exerting on the file cabinet must be equal to the amount of the force that friction is exerting on it. (C) The amount of the force that you're exerting on the file cabinet must be more than the amount of the force that friction is exerting on it. (D) If you were to exert twice as much force on the file cabinet, it would slide across the floor at twice its original speed.

(B) The amount of the force that you're exerting on the file cabinet must be equal to the amount of the force that friction is exerting on it.

You forgot to tip the bartender who brought a Shirley Temple drink to your luxury hotel suite. So you're leaning out over the balcony of your 20th floor suite and dropping solid gold marbles into the tip jar on the ground floor patio bar. You notice that it takes 4 seconds for each marble to fall into the jar, 20 floors below. When each marble has fallen for only 2 seconds, which floor of the hotel is it nearest? [Note: neglect any effects due to the air.] (A) The marble is near the 10th floor. (B) The marble is near the 15th floor. (C) The marble is near the 8th floor. (D) The marble is near the 12th floor.

(B) The marble is near the 15th floor.

Wrapping a hot potato in aluminum foil helps keep the potato warm because the shiny aluminum foil is (A) actually transparent to infrared radiation and allows radiant heat from the room to enter the potato and keep it warm. (B) a very poor emitter of thermal radiation. (C) a poor conductor of heat, so the surface temperature of the foil is much less than the surface temperature of the potato. (D) so thin that it doesn't have enough mass to cool the potato significantly.

(B) a very poor emitter of thermal radiation.

A guitar string that normally vibrates with a fundamental frequency of 110 Hz is also capable of vibrating at 330 Hz. When that higher frequency vibration occurs, the string is vibrating (A) with only one-third of its normal tension. (B) as 3 strings that are each one-third as long as the overall string. (C) with only one-third of its normal amplitude of oscillation. (D) with only one-third of its normal mass.

(B) as 3 strings that are each one-third as long as the overall string.

If you blow across the top of a half full bottle of soda you can produce a clear tone. If you take a drink of soda to reduce the amount of liquid in the bottle and try this again the pitch (frequency) of the sound produced will (A) increase. (B) decrease. (C) stay the same, but only if you blow exactly as hard as before. (D) stay the same, regardless of how hard you blow.

(B) decrease.

The hotter it is outside, the more electric energy an air conditioner must use to remove each joule of heat from the 72 °F indoor air in your home. It must consume more electric energy on a hotter day because (A) entropy flows into your home faster when the outdoor air is hotter. (B) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter. (C) delivering that joule of heat to the outdoor air creates more entropy as the outdoor air gets hotter. (D) heat flows into your home faster when the outdoor air is hotter.

(B) delivering that joule of heat to the outdoor air creates less entropy as the outdoor air gets hotter.

You watch from the ground as a crane lifts a large bucket of cement upward to a construction project. The bucket and cement are moving straight upward at constant velocity. As the crane's cable lifts the bucket, the cable is (A) not doing work on the bucket or the cement it contains. (B) doing work on the bucket and the bucket is doing work on the cement it contains. (C) doing work on the bucket, but the bucket is not doing work on the cement it contains. (D) not doing work on the bucket, but the bucket is doing work on the cement it contains.

(B) doing work on the bucket and the bucket is doing work on the cement it contains.

You are cleaning the siding on your house by spraying water at it from a hose and nozzle. At the center of the stream of water, right where it hits the siding, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches the siding is (A) exactly zero. (B) higher than atmospheric pressure. (C) lower than atmospheric pressure, but more than zero. (D) equal to atmospheric pressure.

(B) higher than atmospheric pressure.

Ice floats on liquid water because (A) the increased pressure on the ice's bottom surface causes the ice to melt and it refreezes on top. (B) ice is less dense than water at 0 °C, so the ice experiences an upward buoyant force that is greater than its downward weight. (C) the solid form of a material always floats on its liquid form. (D) water contains some salt and the salt makes it much heavier than ice.

(B) ice is less dense than water at 0 °C, so the ice experiences an upward buoyant force that is greater than its downward weight.

On a cold morning, you seal your empty plastic water bottle and thus trap the air inside it. Later in the day, the bottle and its contents are much warmer and the elastic sides of the bottle are now stretched outward, so the bottle has slightly more volume than it had in the morning. Since the morning, the air pressure inside the bottle has (A) increased, but the density inside the bottle has stayed the same. (B) increased and the density inside the bottle has decreased. (C) stayed the same, but the density inside the bottle has decreased. (D) increased and the density inside the bottle has increased.

(B) increased and the density inside the bottle has decreased.

At high altitude, a commercial jetliner must compress the outside air before circulating it in the pressurized cabin. But the compressed air must first be sent through an air conditioner because the act of compressing air (A) increases the air's momentum. (B) increases the air's temperature. (C) turns it into a liquid and the air conditioner helps it evaporate back into a gas. (D) reduces the air's energy.

(B) increases the air's temperature.

Compared to a black iron woodstove, a woodstove made out of shiny gold would be (A) equally effective at heating a room because shiny gold and black iron are both dense materials. (B) less effective at heating a room because shiny gold does not radiate heat well. (C) equally effective at heating a room because shiny gold and black iron are both metals. (D) more effective at heating a room because shiny gold does not radiate heat well.

(B) less effective at heating a room because shiny gold does not radiate heat well.

Water hammer occurs when you suddenly stop the flow of water in a pipe. It happens because flowing water has (A) no friction. (B) momentum and can only be stopped by a force. (C) angular momentum and can only be stopped by a torque. (D) acceleration and can only be stopped by a velocity.

(B) momentum and can only be stopped by a force.

Your glass of water has one cube of ice floating at the water's surface. Part of the cube is above the water. When you pour a layer of chilled olive oil onto the water's surface, the ice cube (A) moves downward slightly. (B) moves upward slightly. (C) sinks to the bottom of the water. (D) floats at the same height as before.

(B) moves upward slightly.

You are competing in an archery contest and have just released an arrow toward the target. Neglect any effects due to the air. Once the arrow has left the bow and is heading forward toward the target, it experiences (A) a forward horizontal force until it reaches the midpoint of its trip to the target and then a backward horizontal force for the remainder of its trip. (B) no horizontal force in the forward direction. (C) a forward horizontal force that diminishes gradually as the arrow approaches the target. (D) a forward horizontal force that remains constant all the way to the target.

(B) no horizontal force in the forward direction.

If a golf ball were smooth rather than dimpled, it would (A) curve toward the left after being hit by the club of a right-handed golfer. (B) not travel as far after being hit by a golf club. (C) curve toward the right after being hit by the club of a right-handed golfer. (D) travel much too far after being hit by a golf club.

(B) not travel as far after being hit by a golf club.

If you blow properly across the top of a soft drink bottle, it will emit a tone similar to that of a flute or a pipe organ. As the tone is sounding, air is oscillating back and forth through the mouth of the bottle. Inside the bottle, the air's (A) acceleration remains constant. (B) pressure is alternately increasing and decreasing. (C) pressure remains constant. (D) velocity remains constant.

(B) pressure is alternately increasing and decreasing.

When you strike a match on the side of the match box, you are using sliding friction to (A) push away the protective cap on the match to expose the thermal energy underneath. (B) provide the activation energy needed to initiate the chemical reactions of combustion. (C) melt the wax on the match and allow it to mix with the wood or paper. (D) wear away the protective cap on the match to expose the burning surface underneath.

(B) provide the activation energy needed to initiate the chemical reactions of combustion.

Tightening a guitar string (A) lowers the string's frequency or pitch by softening the string's restoring force. (B) raises the string's frequency or pitch by stiffening the string's restoring force. (C) raises the string's frequency or pitch by softening the string's restoring force. (D) lowers the string's frequency or pitch by stiffening the string's restoring force.

(B) raises the string's frequency or pitch by stiffening the string's restoring force.

Modern double-pane windows provide excellent thermal insulation. The inner surface of one of those panes is coated with a transparent electrical conductor because that coating (A) prevents the argon gas atoms from transferring heat via conduction to the coated pane. (B) reflects infrared light and blocks radiative heat transfer from one pane to the other. (C) improves the thermal conductivity of the coated pane and helps keep it at the same temperature as the other pane. (D) attracts gas atoms and thereby limits convective heat transfer by the argon gas trapped between the panes.

(B) reflects infrared light and blocks radiative heat transfer from one pane to the other.

Houses often emit creaking sounds as they cool off at night. Since sound carries energy, the house must obtain that energy from somewhere. While this energy begins as thermal energy, the sound doesn't appear until the outside temperature drops well below the temperature of the house because (A) building materials become too soft during the day to vibrate with enough efficiency to convert thermal energy into sound energy. (B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air. (C) sound, like heat, can only flow from hotter objects to colder objects. (D) the house's thermal energy increases most rapidly after dark.

(B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air.

You're filming a movie and you arrange for two unoccupied cars to drive horizontally off a tall cliff side-by-side at the same velocity. The Mercedes sedan weighs twice as much as the Mini Cooper. In this situation, the two cars hit the level ground below the cliff at approximately (A) the same distance from the cliff, but the Mercedes sedan hits much sooner than the Mini Cooper. (B) the same time and at the same distance from the cliff. (C) the same time, but the Mercedes sedan hits considerably farther from the cliff than the Mini Cooper. (D) the same time, but the Mini Cooper hits considerably farther from the cliff than the Mercedes sedan.

(B) the same time and at the same distance from the cliff.

A huge abstract iron sculpture has been installed in front of the local art museum. It sits there motionless, "guarding" the main doorway. The sculpture is experiencing two forces: its weight downward and a force upward from the brick courtyard beneath it. We know that these two forces on the sculpture are equal in amount but oppositely directed because (A) Newton's third law requires that forces always appear in equal but oppositely directed pairs. (B) the sculpture is not accelerating, so the two forces must sum to zero. (C) for every action, there is an equal but oppositely directed reaction. (D) the sculpture has zero velocity.

(B) the sculpture is not accelerating, so the two forces must sum to zero.

You and friend are paddling a canoe across a lake. You both reach forward with your paddles raised above the water, lower the paddles into the water, and then pull the paddles backward toward you. The canoe accelerates forward as you pull backward on your paddles, because as you pull backward, (A) the water level behind the canoe rises and the canoe accelerates down the inclined plane that you are producing. (B) the water pushes forward on your paddles. (C) you exert forward forces on your paddles. (D) the weight of the canoe is reduced.

(B) the water pushes forward on your paddles.

The flow of air around a ball can be perfectly laminar only when the ball is traveling extremely slowly through the air. During such laminar flow, the ball experiences (A) neither viscous drag nor pressure drag. (B) viscous drag but not pressure drag. (C) pressure drag but not viscous drag. (D) both viscous drag and pressure drag.

(B) viscous drag but not pressure drag.

After clearing the bar in the high jump, you land softly on a giant mattress. Landing on the mattress is much more comfortable than landing on a sand heap of equal size because (A) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more mass to stop you. (B) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you. (C) you transfer less momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop. (D) you transfer more momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop.

(B) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you.

You drop an extremely bouncy rubber ball on a cement floor and it rebounds upward almost to its original height. Compare the ball's energy and momentum just before it bounced on the floor with its energy and momentum just after bounced off the floor. (A) The ball's energy and momentum changed only a little. (B) The ball's energy and momentum changed significantly. (C) The ball's energy changed only a little, but its momentum changed significantly. (D) The ball's energy changed significantly, but its momentum changed only a little.

(C) The ball's energy changed only a little, but its momentum changed significantly.

You are practicing the trapeze at circus camp and you lose your grip on the bar. You fall into the net far below and bounce comfortably up and down. After a few seconds, you settle down at equilibrium in the net. When during your fall and first rebound upward were you accelerating downward? (A) Only when you had not yet reached the lowest point during your first bounce off the net. (B) Only until you touched the net during your initial fall. (C) Whenever you were above your equilibrium in the net. (D) Only when you were not touching the net during both your fall and your rebound.

(C) Whenever you were above your equilibrium in the net.

Independent, gaseous water molecules can leave the surface of hot water at 212 °F (100 °C) (A) and the surface of room temperature water at 68 °F (20 °C) but not the surface of ice at 0 °F (-18 °C). (B) and the surface of ice at 0 °F (-18 °C) but not the surface of room temperature water at 68 °F (20 °C). (C) and the surfaces of room temperature water at 68 °F (20 °C) and ice at 0 °F (-18 °C). (D) but not the surfaces of room temperature water at 68 °F (20 °C) or ice at 0 °F (-18 °C).

(C) and the surfaces of room temperature water at 68 °F (20 °C) and ice at 0 °F (-18 °C).

Once a baseball leaves the pitcher's hand and is heading toward home plate, it gradually slows down. The primary reason for this slowing is that the air pressure (A) at the front and back of the ball is greater than atmospheric pressure, while the pressure on the sides of the ball is less than atmospheric. (B) at the front and back of the ball is less than atmospheric pressure, while the pressure on the sides of the ball is more than atmospheric. (C) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric. (D) at the front of the ball is equal to atmospheric pressure, while the pressure behind the ball is less than atmospheric.

(C) at the front of the ball is greater than atmospheric pressure, while the pressure behind the ball is approximately atmospheric.

Two cans of soup, one of which weighs twice as much as the other, roll off of a horizontal table together at the same initial velocity. In this situation, (A) both cans hit the floor at approximately the same time, but the heavier can lands considerably farther from the table than the lighter can does. (B) the heavier can hits the floor first and it lands considerably farther from the table than the lighter can does. (C) both cans hit the floor at approximately the same time and at the same distance from the table. (D) the heavier can hits the floor first and it lands considerably closer to the table than the lighter can does.

(C) both cans hit the floor at approximately the same time and at the same distance from the table.

A child is playing on a swing. As long as he doesn't swing too high the time it takes him to complete one full oscillation will be independent of (A) both the length of the ropes supporting the swing and the amplitude of the child's motion. (B) the weight of the child, but not of the amplitude of the child's motion. (C) both the amplitude of the child's motion and of the weight of the child. (D) the amplitude of the child's motion, but not of the weight of the child.

(C) both the amplitude of the child's motion and of the weight of the child.

During the power stroke in one cylinder of a car's engine, the burned fuel and air push the piston out of the cylinder. In accordance with Newton's third law, the piston pushes back on the burned gas. Overall, the (A) burned gas does work on the piston and the gas experiences a rise in temperature. (B) piston does work on the burned gas and the gas experiences a rise in temperature. (C) burned gas does work on the piston and the gas experiences a drop in temperature. (D) piston does work on the burned gas and the gas experiences a drop in temperature.

(C) burned gas does work on the piston and the gas experiences a drop in temperature.

You are taking a nap on the couch. A foam cushion is supporting your head so that your head is in equilibrium. The cushion is dented downward 2 inches from its equilibrium shape. You lift your head to look at the clock, then let your head drop freely against the cushion. Your head dents the cushion downward 4 inches before rebounding back upward. The point at which your head reaches maximum speed during this drop and bounce is when it is (A) just touching the cushion on its trip downward. (B) denting the cushion downward 4 inches. (C) denting the cushion downward 2 inches. (D) just touching the cushion on its trip upward.

(C) denting the cushion downward 2 inches.

At high altitude, a commercial jetliner must compress the outside air before circulating it in the pressurized cabin. But the compressed air must first be sent through an air conditioner because compressing air (A) decreases its humidity. (B) turns it into a liquid and the air conditioner's evaporator allows it to return to a gas. (C) increases its temperature. (D) increases its humidity.

(C) increases its temperature.

A friend suggests that you invest in a new invention that supposedly absorbs heat from the room and converts it into electricity. According to a brochure, the device sits in the middle of the room, gradually cooling the room air while providing a steady and endless supply of electric power. You wisely choose not to invest in the device because in order to work as described, it would have to do something impossible-it would have to (A) turn work into heat, or more precisely, into thermal energy. (B) violate the conservation of energy. (C) lower the world's total entropy. (D) turn stored energy into power.

(C) lower the world's total entropy.

To win a stuffed animal at the state fair, you simply need to drop a glass marble onto a stationary glass plate and have the marble come to rest on that plate. Unfortunately, when the marble hits the plate, it bounces upward because the marble (A) transfers a large amount of momentum and energy to the plate. (B) retains essentially all of its momentum but transfers a large amount of energy to the plate. (C) retains essentially all of its energy but transfers a large amount of momentum to the plate. (D) retains essentially all of its energy and momentum.

(C) retains essentially all of its energy but transfers a large amount of momentum to the plate.

If the earth had no atmosphere, the temperature at the earth's surface would be (A) almost that of empty space-a few degrees above absolute zero. (B) essentially the same as it is now. (C) significantly cooler than it is now. (D) significantly hotter than it is now.

(C) significantly cooler than it is now.

Moments before it's ignited by the sparkplug, the mixture of fuel and air inside an automobile engine cylinder is compressed to very high density. During the compression process, the mixture's (A) temperature rises dramatically but its pressure drops. (B) temperature drops dramatically but its pressure rises. (C) temperature rises dramatically and so does its pressure. (D) temperature stays the same but its pressure rises.

(C) temperature rises dramatically and so does its pressure.

Goose down is the soft, fluffy feathers near a goose's skin. The reason that a goose down jacket keeps you so warm in the winter is that (A) goose down's white coloring assists the radiative transfer of heat from the outer surface of the coat to your skin. (B) goose down's low average density reduces its buoyant force. (C) the fine structure of the goose down traps air and prevents it from undergoing convection. (D) the fibrous material in goose down is a poorer conductor of heat than the air it displaces.

(C) the fine structure of the goose down traps air and prevents it from undergoing convection.

When you pull a tablecloth out from under a set of dishes, it's important to pull the cloth as fast as possible because (A) the work done on the dishes by the cloth is proportional to the time during which the cloth pulls on them. (B) the weight of the dishes on the cloth is proportional to the time during which the cloth is moving. (C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them. (D) the force of sliding friction that the cloth exerts on the dishes is proportional to the time during which the cloth is moving.

(C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them.

The reason that a watch with a balance ring and a spring keeps good time is that (A) it contains a quartz crystal. (B) the ring oscillates back and forth with a constant frequency determined principally by the ring's weight and the spring's mass. (C) the ring oscillates back and forth with a constant frequency determined principally by the ring's rotational mass and the spring's stiffness. (D) the ring oscillates back and forth with constant frequency determined principally by the force of gravity and the length of the pendulum rod.

(C) the ring oscillates back and forth with a constant frequency determined principally by the ring's rotational mass and the spring's stiffness.

Because of bad planning during the design and construction of a high-rise apartment building, all 50 floors of the building receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction) (A) the same on all floors, but the speed of the spraying water is greater on higher floors. (B) smaller on higher floors (C) the same on all floors, but the speed of the spraying water is smaller on higher floors. (D) greater on higher floors.

(C) the same on all floors, but the speed of the spraying water is smaller on higher floors.

You are watching children play a game of tug-o-war with a plastic clothesline. The two teams are pulling at opposite ends of the cord and each team is trying to drag the other team into a mud puddle that lies between them. After a few minutes without progress, the team on the right suddenly pulls hard toward the right. The team on the left has anticipated this threat and is able to keep their end of the rope from moving. The right end of the rope stretches toward the right and the rope breaks. Breaking the rope required energy and that energy was provided by (A) both teams. (B) the team on the left. (C) the team on the right. (D) neither team. It was instead provided by chemical potential energy in the rope itself.

(C) the team on the right.

Heat flows spontaneously from a warm hot tub to a cool swimming pool because this heat transfer causes (A) the entropy of the warmer object (the hot tub) to increase. (B) the total entropy of the two objects to decrease. (C) the total entropy of the two objects to increase. (D) the entropy of the cooler object (the pool) to decrease.

(C) the total entropy of the two objects to increase.

You are swinging a bucket full of water around you in a big horizontal circle at a constant speed. You are at the center of its circular path. The net force on the bucket points directly (A) downward. (B) away from you. (C) toward you. (D) along the bucket's velocity (along its direction of travel).

(C) toward you.

Ice cubes gradually shrink in a frost-free freezer because (A) the ice melts periodically and some of it evaporates before it can refreeze. (B) the freezer mice like to nibble on the ice cubes. (C) water molecules go directly from solid ice to gaseous water vapor. (D) the ice melts periodically and some of it drips into the bottom of the freezer.

(C) water molecules go directly from solid ice to gaseous water vapor.

You are riding a motorcycle at constant velocity along a horizontal road while wearing a heavy leather jacket. As you cruise down road, you are doing (A) (positive) work on the jacket and it is doing negative work on you. (B) (positive) work on the jacket and it is doing (positive) work on you. (C) zero work on the jacket and it is doing zero work on you. (D) negative work on the jacket and it is doing (positive) work on you.

(C) zero work on the jacket and it is doing zero work on you.

You are in a spaceship far from earth and you fire a cannonball into frictionless, empty space. While the cannonball travels forward through space at enormous speed, the net force on that cannonball is (A) the force of the cannonball's momentum. (B) the force of the cannonball's velocity. (C) zero. (D) the force of the cannonball's mass.

(C) zero.

You and your friend carry identical water bottles from the first floor to the fifth floor. You start side-by-side and you finish side-by-side, but one of you uses the stairs while the other climbs straight up a ladder. Which of you did the most work on your water bottle? (A) The person who takes the most time to reach the fifth floor does the most work on the water bottle. (B) The person who uses the stairs does the most work on the water bottle. (C) The person who climbs the ladder does the most work on the water bottle. (D) Neither. You both do the same work on the water bottle.

(D) Neither. You both do the same work on the water bottle.

Two children are trying to lift toys using large helium balloons. One child is located in Norfolk, where the altitude is roughly sea level, and the other child is located in Denver, where the altitude is about 5,000 feet above sea level. Their balloons are identical in size and shape, and both locations have the same temperature and weather. Which balloon, if any, can lift more weight? (A) The Denver balloon can lift more weight. (B) The balloon with a picture of Dwayne Johnson on it can lift more weight, because he's so strong. (C) They can both lift equal weights. (D) The Norfolk balloon can lift more weight.

(D) The Norfolk balloon can lift more weight.

You place three nonflammable objects in a fire. They are identical in shape and size, but one object is black, the second is white, and the third is shiny silver. After a few minutes, all three objects are at the same temperature: 1800 °C. They remain solid and are now glowing with thermal radiation. Which one is glowing most brightly? (A) The third object (silver). (B) The second object (white). (C) They are all glowing with equal brightness. (D) The first object (black).

(D) The first object (black).

Some satellites orbit the earth at such large distances that they are never in the earth's shadow. These satellites are constantly exposed to full sunlight. With no air around them to take away heat, why don't these satellites continue to grow hotter forever? (A) They use air conditioners to eliminate the excess thermal energy as rapidly as it arrives. (B) They have solar panels that convert the sun's thermal radiation completely into electricity and avoid any need to eliminate heat. (C) Because they are isolated from the sun by empty space, the sun's heat can't reach them and they don't experience any changes in temperature. (D) Their temperatures rise until they are able to radiate heat away into space as fast as it arrives from the sun.

(D) Their temperatures rise until they are able to radiate heat away into space as fast as it arrives from the sun.

When you drop a beanbag on cement, the bag doesn't bounce. Suppose you are playing tennis with a beanbag instead of a tennis ball. How should you adjust your tennis racket to make the beanbag travel as fast as possible after you hit it with the racket? (A) You should tighten the strings so that the racket surface is like a firm trampoline. (B) You should replace the strings with a rigid carbon-fiber plate so that the racket surface acts like cement. (C) You should add mass to the racket so that it carries more momentum. (D) You should loosen the strings so that the racket surface is like a soft trampoline.

(D) You should loosen the strings so that the racket surface is like a soft trampoline.

To transform 1 kilogram of boiling-hot water at 100 °C into 1 kilogram of steam at 100 °C, you must (A) remove a large amount of heat to the water. (B) allow the water to boil for less than 5 minutes, although it doesn't require any additional heat. (C) allow the water to boil for more than 5 minutes, although it doesn't require any additional heat. (D) add a large amount of heat to the water.

(D) add a large amount of heat to the water.

If you try to cook vegetables with 100 °C air, it takes a very long time. But if you cook those same vegetables with 100 °C steam, they cook very quickly. This is because the steam (A) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. (B) causes moisture inside the vegetables to boil and transfer heat to the vegetables. (C) causes moisture inside the vegetables to boil and absorb heat from the vegetables. (D) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

(D) condenses on the colder vegetables and releases a large amount of heat to the vegetables.

You are standing in a cable car that is moving up the side of a mountain at a constant velocity. The force that the cable car is exerting on you points (A) horizontally forward, toward the mountain itself. (B) down and forward, at right angles to the cable itself. (C) up and forward, in the direction of the cable itself. (D) directly upward.

(D) directly upward.

When you jump while standing on a bathroom scale, it briefly reads more than your actual weight. During that moment, it's exerting an upward force on you that is (A) equal to your weight and your velocity is constant. (B) greater than your weight and your velocity is constant. (C) equal to your weight and you are accelerating upward. (D) greater than your weight and you are accelerating upward.

(D) greater than your weight and you are accelerating upward.

If you strike a stiff, spring-like surface with a mallet and listen to the sound it emits, you'll notice that this sound is more complicated than that emitted by a string or a thin bar. That's because surfaces (A) are not harmonic oscillators. (B) are harmonic oscillators. (C) have overtones that are integer multiples of their fundamental frequencies. (D) have overtones that are not integer multiples of their fundamental frequencies.

(D) have overtones that are not integer multiples of their fundamental frequencies.

You are mountain biking through the woods and come to a deep gully. The bottom of the gully is a smooth bowl shape without any obstacles. Neglecting friction and air resistance, you are able to coast down one side and back up the other without pedaling. When you are at the bottom of the gully, you feel (A) heavier than normal since you are accelerating downward. (B) lighter than normal since you are accelerating upward. (C) neither heavier nor lighter than normal since you are not accelerating at the bottom. (D) heavier than normal since you are accelerating upward.

(D) heavier than normal since you are accelerating upward.

Flowing honey is less likely to become turbulent than flowing water because (A) water's larger pressure favors turbulent flow. (B) water's larger viscosity favors turbulent flow. (C) honey's larger density favors laminar flow. (D) honey's larger viscosity favors laminar flow.

(D) honey's larger viscosity favors laminar flow.

As air flows around a fast-moving ball, that air has difficulty maintaining laminar flow from the ball's sides to the ball's back. During the air's passage from sides to back, the pressure along each streamline (A) decreases and the airflow slows down. (B) increases and the airflow speeds up. (C) decreases and the airflow speeds up. (D) increases and the airflow slows down.

(D) increases and the airflow slows down.

A satellite is traveling around the earth in a circular orbit. It briefly fires its rocket engine to increase its speed in the forward direction; it is suddenly going faster but its direction of travel didn't change. As a result of this speed increase, the orbiting satellite's average distance from the center of the earth (A) remains unchanged, but the orbit is no longer circular. (B) remains unchanged and the orbit continues to be circular. (C) decreases. (D) increases.

(D) increases.

When wood burns in air, the water and carbon dioxide molecules that form as the result of combustion reactions have (A) more chemical potential energy than the original wood and air molecules (B) more chemical momentum than the original wood and air molecules (C) less chemical momentum than the original wood and air molecules (D) less chemical potential energy than the original wood and air molecules

(D) less chemical potential energy than the original wood and air molecules

You are juggling grapefruits in your hands and are about to toss one far above your head. After it leaves your hand, the grapefruit will experience (A) both an upward force and the downward force of its weight as it rises. The upward force will gradually diminish to zero at the grapefruit's peak height, after which the grapefruit will experience only the downward force of its weight. (B) an upward force as it rises. This upward force will gradually diminish to zero at the grapefruit's peak height, after which the grapefruit will experience only the downward force of its weight. (C) the upward force of its weight as it rises. Once the grapefruit reaches its peak height, it will begin to experience the downward force of its weight. (D) only the downward force of its weight, both before and after it reaches its peak height.

(D) only the downward force of its weight, both before and after it reaches its peak height.

You have installed a fountain in your backyard fish pond. Water flows through a pipe to a nozzle, then rises 10 feet upward in the open air. As water flows along a streamline in this system, its energy changes forms several times. As the water passes through the nozzle its energy transforms from (A) kinetic energy to pressure potential energy and as the water rises to its peak height its energy transforms from pressure potential energy to gravitational potential energy. (B) pressure potential energy to gravitational energy and as the water rises to its peak height its energy transforms from gravitational energy to pressure potential energy. (C) kinetic energy to pressure potential energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy. (D) pressure potential energy to kinetic energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy.

(D) pressure potential energy to kinetic energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy.

The living room is cold, so your friend brings in an electric hotplate to warm the air. To make sure that no one touches the red-hot surface of that hotplate, your friend places the hotplate on a high ledge near the ceiling. Heat will flow from the hotplate to people sitting near the floor (A) primarily via convection and radiation, with almost no heat flowing via conduction. (B) equally poorly via conduction, convection, and radiation, and the room will remain cold. (C) equally well via conduction, convection, and radiation, and the room will become warm. (D) primarily via radiation, with almost no heat flowing via conduction or convection.

(D) primarily via radiation, with almost no heat flowing via conduction or convection.

When you ride a bicycle, the ground exerts an upward support force on the wheel. When you turn the bicycle, the ground also exerts a horizontal frictional force on the wheel that causes you to accelerate sideways. Leaning the bicycle toward the inside of a turn keeps you from flipping over because the overall force that the ground exerts on the wheel (A) points directly upward so that you don't fall downward. (B) points exactly at right angles to your center of mass and exerts a torque on you that keeps you from falling over. (C) is exactly zero and causes no acceleration of your center of mass. (D) produces zero torque on you and the bicycle about your combined center of mass.

(D) produces zero torque on you and the bicycle about your combined center of mass.

An airplane cruises at constant velocity into a region of calm, motionless air. After the plane has passed through that region of air, the air's total momentum is (A) still zero, but the air may be turbulent (contain swirls and vortices). (B) downward and forward (in the direction of the airplane's motion). (C) downward and backward (in the direction opposite the airplane's motion). (D) straight downward.

(D) straight downward.

You are filling a large lightweight dry cleaning bag with helium. At first, the plastic bag doesn't float. But as you keep adding helium to the bag, it eventually begins floating because (A) the helium-filled bag's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (B) the upward buoyant force on a bag full of helium is larger than the buoyant force on an identical bag full of air. (C) the average pressure of the helium-filled bag increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces.

(D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces.

You are filling a large plastic bag with helium. At first, the bag doesn't float. But as you keep inflating the bag with helium, it eventually begins floating because (A) the helium-filled bag's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. (B) the average pressure of the helium-filled bag increases as it fills and its pressure eventually becomes greater than that of the air it displaces. (C) the upward buoyant force on a bag full of helium is larger than the buoyant force on an identical bag full of air. (D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces.

(D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces.