PHY 2020 Final - Pradhan (Abridged)

Scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is a valid hypothesis, there must be a test for proving it---- A) wrong. B) right.

A) wrong.

Airplane flight best illustrates A) Archimedes' principle. B) Pascal's principle. C) Bernoulli's principle. D) None of the above

C) Bernoulli's principle.

When heat is added to boiling water, its temperature A) increases. B) decreases. C) does not change.

C) does not change.

A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is A) less than its weight. B) more than its weight. C) equal to its weight.

C) equal to its weight.

Two equal-sized buckets are filled to the top with water. One of the buckets has a piece of wood floating in it, making its total weight __________. A) more than the weight of the other bucket B) less than the weight of the other bucket C) equal to the weight of the other bucket D) None of the above

C) equal to the weight of the other bucket

A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set? A) 2 J B) 10 J C) 20 J D) 40 J E) 800 J

D) 40 J

If you double the radiating surface area of a star, its power output increases by a factor of A) 2 B) 4 C) 8 D) 16

A) 2

A ball is thrown upwards from the surface of the earth at the speed 10m/s. It returns to the same position. How long does it stay in the air (neglect the air resistance)? A) 2s B) 4s C) 5s D) 0s

A) 2s

A shiny, white transparent surface prevents heat transfer because A) It has emissivity of zero and reflects all light that strikes it. B) It has emissivity of 1 and reflects all light that strikes it. C) It has emissivity of zero and absorbs all light that strikes it. D) It has emissivity of 1 and absorbs all light that strikes it.

A) It has emissivity of zero and reflects all light that strikes it.

Which is the following is not a vector quantity? A) Mass B) Weight C) Force D) Acceleration E) None of these

A) Mass

"Two objects in thermal equilibrium with a third object are in thermal equilibrium with each other." Which Law of Thermodynamics is this? A) Zeroth B) First C) Second D Third

A) Zeroth

Compared to a glass of ice water with ice in it, a glass of plain ice-cold water without ice on a warm day will warm up A) faster. B) slower. C) in the same amount of time. D) None of the above choices are true.

A) faster.

Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. In presence of air-resistance, the ball to reach the ground first is the ---- A) lead-filled ball. B) regular ball. C) same for both

A) lead-filled ball.

If the specific heat of water were lower than it is, ponds in the cold of winter would be A) more likely to freeze. B) less likely to freeze. C) neither more nor less likely to freeze.

A) more likely to freeze.

If you push for a half hour or a whole hour against a stationary wall A) no work on the wall is done in either case. B) half as much work is done during the half hour. C) twice as much work is done during the half hour. D) it is impossible to determine how much work is done.

A) no work on the wall is done in either case.

While an object near the Earth's surface is in free fall, its A) velocity increases. B) acceleration increases. C) mass increases. D) velocity decreases.

A) velocity increases.

A completely submerged object always displaces its own A) volume of fluid. B) weight of fluid. C) density of fluid. D) all of these E) none of these

A) volume of fluid.

When water vapor condenses on the inside of a window, the room becomes slightly A) warmer. B) cooler. C) neither warmer nor cooler.

A) warmer.

A balloon is buoyed up with a force equal to the A) weight of air it displaces. B) density of surrounding air. C) atmospheric pressure. D) weight of the balloon and contents. E) all of these

A) weight of air it displaces.

Suppose you walk on red-hot coals with bare feet. If bits of the coals do not stick to your feet, it would be best if your feet are A) wet. B) dry. C) warm. D) cold. E) very hot.

A) wet.

An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward (neglecting air-resistance) at an angle instead, its acceleration will be A) 0 g. B) 1 g downward. C) 1 g upward. D) larger than 1 g. E) none of these

B) 1 g downward.

Before ice can form on a lake, all the water in the lake must be cooled to A) zero degrees C. B) 4 degrees C. C) minus 32 degrees C. D) None of the above. Ice can form at the surface regardless of the water temperature below.

B) 4 degrees C.

A 500N blimp hovers in the air. The buoyant force acting on it is A) zero. B) 500N . C) less than 500N. D) more than 500N. E) None of the above

B) 500N .

Lead sinkers actually float on the surface of liquid mercury. Which takes up more space: 1 kg of mercury or 1 kg of lead? A) Mercury B) Lead C) Neither take up any space D) Not enough information is given

B) Lead

Near the top of a mountain, water in an open pot boils at A) a higher temperature than at sea level. B) a lower temperature than at sea level. C) the same temperature as at sea level. D) None of the above choices are true.

B) a lower temperature than at sea level.

When an object is partly or wholly immersed in a liquid, it is buoyed up A) by a force equal to its own weight. B) by a force equal to the weight of liquid displaced. C) and floats because of Archimedes principle. D) but nevertheless sinks. E) none of these

B) by a force equal to the weight of liquid displaced.

If no external forces are acting on a moving object, it will A) continue moving at the same speed. B) continue moving at the same velocity. C) move slower and slower until it finally stops.

B) continue moving at the same velocity.

)The gulf stream is one of nature's ways of transferring energy through A) conduction. B) convection. C) transmission. D) radiation.

B) convection.

Consider a sample of ice at 0 degrees C. If the temperature is decreased, the volume of the ice A) increases. B) decreases. C) stays the same.

B) decreases.

Consider a sample of water at 0 degrees C. If the temperature is slightly increased, the volume of the water A) increases. B) decreases. C) remains the same.

B) decreases.

The stretching out of time due to motion is called time A) stretching. B) dilation. C) contraction. D) warp. E) expansion.

B) dilation.

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is A) zero. B) doubled. C) quadrupled. D) unchanged.

B) doubled.

A popular swinging-balls apparatus consists of an aligned row of identical elastic balls that are suspended by strings so they barely touch each other. When two balls are lifted from one end and released, they strike the row and two balls pop out from the other end. If instead one ball popped out with twice the speed of the two, this would be a violation of conservation of A) momentum. B) energy. C) both of these D) none of these

B) energy.

When water at 4 degrees C is heated slightly it expands. When water at 4 degrees C is cooled slightly, it A) contracts. B) expands. C) neither contracts nor expands.

B) expands.

For increased atmospheric pressure, the boiling temperature of a liquid A) goes down. B) goes up. C) remains at 100 degrees C.

B) goes up.

According to Newton, the greater the masses of interacting objects, the A) less the gravitational force between them. B) greater the gravitational force between them. C) greater the force between them by the square of the masses.

B) greater the gravitational force between them.

It is a hot summer day and your friend's apartment has no air conditioning. However, a brand new refrigerator lies unopened in the center of the living room. Being a creative person, your friend closes all the doors and windows of the apartment, unpacks the refrigerator, plugs it in, and turns it on. Your friend then opens the refrigerator door and uses a small fan to circulate the air past the refrigerator and throughout the room. After the refrigerator has operated for a few minutes, the average temperature in the room is A) lower than it was before. B) higher than it was before. C) the same as it was before and the temperature is uniform throughout the room. D) the same as it was before, but some regions are hotter and others are colder.

B) higher than it was before.

If an object's mass is decreasing while a constant force is applied to the object, the acceleration A) decreases. B) increases. C) remains the same.

B) increases.

Which of the following normally warms up fastest when heat is applied? A) water B) iron C) glass D) wood E) All of the above choices are equally true.

B) iron

)In the poem "When You Are Old" by William Butler Yeats there is the following concluding line: "and bending down beside the glowing bars, murmur, a little sadly, how love fled and paced upon the mountains overhead and hid his face amid a crowd of stars." The glowing bars refer the metal bars that hold wood in a fireplace and they are transmitting heat energy by A) radiation only B) radiation and conduction. C) conduction only D) convection

B) radiation and conduction.

People fighting forest fires carry emergency tents that have shiny aluminum outer surfaces. If there is trouble, a fire fighter can lie under the tent to block the heat from burning trees overhead. The tent helps because A) conduction carries heat downward toward the fire fighter and the aluminum tent conducts that heat harmlessly into the ground. B) radiation carries heat downward toward the fire fighter and the aluminum tent reflects most of that radiation. C) convection carries heat downward toward the fire fighter and the aluminum tent blocks most of the heat carried by convection. D) both conduction and radiation carry heat downward toward the fire fighter and the aluminum tent blocks most of that heat.

B) radiation carries heat downward toward the fire fighter and the aluminum tent reflects most of that radiation.

Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr? A) the 30 km/hr car B) the 60 km/hr car C) Both have the same kinetic energy. D) More information is needed about the distance traveled.

B) the 60 km/hr car

It is correct to say that impulse is equal to A) momentum. B) the change in momentum it produces. C) the force multiplied by the distance the force acts. D) velocity multiplied by time.

B) the change in momentum it produces.

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is A) 0 N. B) 0.1 N. C) 1 N. D) 9.8 N. E) none of these

C) 1 N.

10). The weight of a 1-kg mass at the Earth's surface is about A) 1 kg. B) 4.9 N. C) 10 N. D) 100 N. E) none of these

C) 10 N.

Steam burns are more damaging than burns caused by boiling water because steam A) gives up additional energy when it condenses. B) has more energy per kilogram than boiling water. C) Choices A and B are both correct. D) Choices A and B are both incorrect.

C) Choices A and B are both correct.

Heat energy is measured in units of A) joules. B) calories. C) Choices A and B are both true. D) Kelvin

C) Choices A and B are both true.

)Why are good thermal conductors generally good electric conductors also? A) Heat and electricity are the same things. B) The molecules in both don't move around very much. C) Electron motion is responsible for determining both properties. D) The answer depends on the specific metal.

C) Electron motion is responsible for determining both properties.

Which of the following quantities is not conserved? A) Energy B) Angular momentum C) Entropy D) Momentum

C) Entropy

Which temperature scale has 273 as the boiling point of water? A) Fahrenheit B) Celsius C) No scale D) Kelvin

C) No scale

"The entropy of an isolated system never decreases." Which Law of Thermodynamics is this? A) Zeroth B) First C) Second D Third

C) Second

6) Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom ------- A) after the light block. B) before the light block. C) at the same time as the light block.

C) at the same time as the light block.

The pressure in a liquid depends on liquid A) density. B) depth. C) both of these D) neither A or B

C) both of these

The first law of thermodynamics is a re - statement of the law of A) conservation of momentum B) thermal equilibrium C) conservation of energy D) averages

C) conservation of energy

When you float in fresh water, the buoyant force that acts on you is equal to your weight. When you float higher in the high-density water of the Dead Sea, the buoyant force that acts on you is A) greater than your weight. B) less than your weight. C) equal to your weight.

C) equal to your weight.

If a non-rotating object has no acceleration, then we can say for certain that it is A) at rest. B) moving at constant non-zero velocity. C) in mechanical equilibrium. D) all of these E) none of these

C) in mechanical equilibrium.

8). A kilogram is a measure of an object's A) weight. B) force. C) mass. D) size.

C) mass.

When an ice cube in a glass of water melts, the water level A) rises. B) falls. C) remains the same.

C) remains the same.

A ring, a cylinder, and a solid sphere begin rolling down a hill together. Given that the rotational inertia of the solid sphere is the least and that of the ring is the most , the one to reach the bottom first is the A) ring B) cylinder. C) sphere. D) They all reach the bottom at the same time. E) Not enough information is given.

C) sphere.

Compared to falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the A) carpeted floor provides a smaller impulse. B) stopping time is shorter on the carpet. C) stopping time is longer on the carpet. D) carpet provides a smaller impulse and a longer time.

C) stopping time is longer on the carpet.

The center of mass of a human body is located at a point A) that is fixed, but different for different people. B) that is always directly behind the belly button. C) that changes as a person bends over. D) none of these

C) that changes as a person bends over.

You are riding in a hot air balloon. You have not used the burner for some time and the balloon begins to sink. Assuming that no air is allowed to leave or enter the balloon, A) the average density of the balloon remained constant and the buoyant force on the balloon became less than its weight. B) the average density of the balloon became greater than the surrounding air and the buoyant force on the balloon remained constant. C) the average density of the balloon became greater than the surrounding air and the buoyant force on the balloon became less than its weight. D) the balloon became heavier.

C) the average density of the balloon became greater than the surrounding air and the buoyant force on the balloon became less than its weight.

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is A) greater on the bug. B) greater on the car. C) the same for both.

C) the same for both.

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about -------- A) twice as much. B) half as much. C) the same. D) four times as much.

C) the same.

A golfer drives her golf ball from the tee down the fairway in a high arcing shot. When the ball is at the highest point of its flight: A) the velocity and acceleration are both zero B) the x-velocity is zero and the y-velocity is zero C) the x-velocity is non-zero and the y-velocity is zero D) the velocity is non-zero and the acceleration is zero

C) the x-velocity is non-zero and the y-velocity is zero

Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are A) beyond the main pull of Earth's gravity. B) above the Earth's atmosphere. C) without support forces. D) all of these E) none of these

C) without support forces.

A 5 kg ball has a acceleration of 2 m/s2. The the magnitude of the force responsible for producing this acceleration is A) 3 N B) 4 N C) 10 kg D) 10 N E) none of these

D) 10 N

If you double the absolute temperature of a star, its power output increases by a factor of A) 2 B) 4 C) 8 D) 16

D) 16

22) An object in mechanical equilibrium is an object A) at rest. B) moving with constant velocity. C) having no acceleration. D) all of these

D) all of these

9). An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration A) quadruples. B) doubles. C) stays the same. D) halves. E) none of these

D) halves.

While a car travels around a circular track at a constant speed, its A) acceleration is zero. B) velocity is zero. C) inertia is zero. D) none of the above

D) none of the above

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that A) the milk carton has no acceleration. B) there is an action-reaction pair of forces. C) gravity tends to hold the milk carton secure. D) the milk carton has inertia. E) none of these

D) the milk carton has inertia.

Ice is put in a cooler to cool the contents. To speed up the cooling process, the ice can be A) wrapped in newspaper. B) drained of ice water periodically. C) kept out of contact with the food. D) kept in one solid chunk. E) covered with salt.

E) covered with salt.