PHYS 101 Exam 2 Review

You are bored during the summertime when school is not in session and you decide to do an experiment where you compare the properties of water and air. If the density of air is 1.25 kg/m3 and the density of water is 1000 kg/m3 , what volume of air weighs the same as 1 liter of water?

A) 0.00125 liters B) 1.25 liters C) 125 liters D) 800 liters D) 800 liters

The vessels shown below all contain water to the same height. Rank them according to the pressure exerted by the water on the vessel bottoms, least to greatest.

A) 1, 2 ,3, 4 B) 4, 3, 2, 1 C) 3, 4, 2, 1, D) All pressure are the same D) All pressure are the same

A ball hits a wall going 10 m/s, and bounces off going 7 m/s. The coefficient of restitution is

A) 1.41 B) 0.70 C) 0.49 D) -17 m/s B) 0.70

Bolts work because they act like very strong springs and extend slightly when they are tightened. Suppose a steel bolt has spring constant 1.8x108 N/m. How far would it have to stretch in order to provide a force 2000N?

A) 1.8x10-3 m B) 1.8x10-8 m C) 1.11 m D) 1.11x10-5 m D) 1.11x10-5 m

You are swinging a tin can around your head in a perfectly horizontal circle of radius 4 m. (This is really not possible but we're saying it almost happens.) If the speed of the can is 4 m/s and its mass is 2 kg, what inward force is required to keep the can moving in the circle?

A) 1/16 N B) 2 N C) 16 N D) 8 N D) 8 N

You are swinging a tin can around your head in a perfectly horizontal circle of radius 4 m. (This is really not possible but we're saying it almost happens.) If the speed of the can is 4 m/s and its mass is 2 kg, what inward force is required to keep the can moving in the circle?

A) 1/16 N B) 2 N C) 16 N D) 8 N D) 8 N

You are swinging a tin can around your head in a perfectly horizontal circle of radius 4 m. (This is really not possible but we're saying it almost happens.) If the speed of the can is 4 m/s what is its acceleration?

A) 1/4 m/s2 B) 4 m/s2 C) 16 m/s2 D) 4 m/s B) 4 m/s2

The coefficient of restitution for a particular ball is 0.45. If he ball hits a surface traveling at 100 m/s its rebound speed will be

A) 100 m/s B) 90 m/s C) 45 m/s D) 45 m/s2 C) 45 m/s

A popular playground toy is a flexible seat that has automobile springs attached to it for a little bounce. When a 200 N child sits on the toy, it compresses 5 mm downward. What is the ride's spring constant?

A) 1000 N B) 5 mm C) 40000 N/m D) 1000 N/m C) 40000 N/m

The brake system in most cars makes use of a hydraulic system. This system consists of a fluid filled tube connected at each end to a piston. Assume that the piston attached to the brake pedal has a cross sectional area of one half a square inch and the piston attached to the brake pad has a cross section area of two square inches. When you apply a force of 10 pounds to the piston attached to the brake pedal, the force at the brake pad will be,

A) 5 pounds. B) 10 pounds. C) 20 pounds. D) 40 pounds. D) 40 pounds.

What is the gravitational force that two 100 kg persons exert on each other when standing 1m apart?

A) 6.672x10-7 N B) 1 N C) 6.672x10-11 N D) 10,000 N A) 6.672x10-7 N

Which system is in a state of stable equilibrium?

A) A marble in the bottom of a spherical bowl. B) A Marble on top of a spherical bowl. C) A marble on a flat, level surface. D) A marble rolling down an inclined surface. A) A marble in the bottom of a spherical bowl.

Consider the Moon orbiting the Earth. _______ is the centripetal force for the orbit, and one could therefore measure the mass of the ________ by studying the Moon's orbit.

A) Drag; Earth B) Tension; Moon C) Gravity; Moon D) Gravity; Earth D) Gravity; Earth

An object is in stable equilibrium only when

A) Its total potential energy rises whenever it reorients. B) Its total potential energy lowers whenever it reorients. C) It is not moving D) It is moving A) Its total potential energy rises whenever it reorients.

Water weighs about 10 N per liter. A 4.0 kg ball floats on the water's surface. What is the weight of the water being displaced by the ball?

A) Much less than 2000 N B) Much more than 40 N C) About 40 N D) Not enough information is given C) About 40 N

You are swinging a 2 kg tin can around your head in a perfectly horizontal circle of radius 1 m with a speed of 6 m/s. (This is really not possible but we're saying it almost happens.) If the string can safely exert a force of 30 N will it be able to swing the can?

A) No because the required force is 36 N. B) No because the required acceleration is 36 m/s2. C) Yes because only linear acceleration would break the string. D) Yes because the weight of the can does not matter. A) No because the required force is 36 N.

Cities have to use water towers to supply water to because

A) The water tower has a vault of air that is pressurized. B) Water moves fastest at the bottom of the water tower and this speed is transmitted uniformly throughout all water pipes below. C) Water pressure at the top of the tower is transmitted through the water pipes. D) Water pressure at the bottom of the tower is much higher than at the top. D) Water pressure at the bottom of the tower is much higher than at the top.

For an object that is floating on a fluid,

A) The weight of fluid displaced is less than its weight. B) The weight of the fluid displaced is greater than the object's weight. C) The weight of the fluid displaced equals the object's weight. D The weight of the object becomes less than in air. C) The weight of the fluid displaced equals the object's weight.

Suppose you are spending your weekend on roller skates trying to get momentum from somewhere. Which of the following will give you momentum in the north direction?

A) Throwing your keys southward. B) Throwing your keys northward. C) Bending down and throwing your keys straight up. D) (B) or (C). A) Throwing your keys southward.

You are riding an amusement park ride where you are strapped to the inside of a giant metal wheel that is rotating quite rapidly. Your acceleration is

A) Zero B) Straight down C) Toward the center D) Straight up C) Toward the center

Suppose you are standing on a bathroom scale when you are flying in a jet airplane. For a moment the scale reads more than your actual weight. During that moment, it's exerting an upward force on you that is greater than your weight and you are

A) accelerating upward. B) accelerating downward. C) not accelerating. D) accelerating sideways. A) accelerating upward.

Your apartment window opens 20 meters (65 feet) above a lemonade stand. Your friend lowers a long plastic tube out the window until its end enters the tank of delicious lemonade far below. She then begins to suck on the other end of the tube in hopes of getting a free drink. To her dismay, she never tastes a drop because

A) atmospheric pressure cannot support a column of lemonade 20 meters tall. B) lemonade is too thick to pass through a tube that long. C) the tube has an average density that is larger than that of lemonade, so the buoyant force cannot support its weight. D) the tube's acceleration is downward, so it prevents the lemonade's velocity from being upward. A) atmospheric pressure cannot support a column of lemonade 20 meters tall.

Suppose you are standing on a bathroom scale when you are flying in a jet airplane. For a moment the scale reads less than your actual weight. During that moment, it's exerting an upward force on you that is

A) greater than your weight B) equal to zero C) equal to your weight. D) less than your weight. A) greater than your weight

Suppose you have two containers with liquid in them. One has a density of 760 kg/m3 and the other has a density of 910 kg /m3. If an object floats in one container and sinks in the other, the density of the object

A) has a value equal to the difference in densities of the two liquids. B) must have a value equal to the average densities of the two liquids. C) has a value less than 760 kg/m3 or greater than 910 kg/m3 D) has a value between 760 kg/m3 and 910 kg/m3. D) has a value between 760 kg/m3 and 910 kg/m3.

The curves on bicycle racetracks are steeply banked, so that the inner edge of each curve is much lower than its outer edge. This banking tips the support force that the track exerts on the bicycle wheel toward the center of each turn. That center-directed or centripetal force on the bicycle is important because it

A) helps the bicycle accelerate inward to complete each turn without skidding. B) it does work on the bicycle during each turn and thus increases the bicycle's energy. C) balances the outward centrifugal force that the bicycle experiences as it completes each turn, so that the bicycle experiences zero net force. D) it does negative work on the bicycle during each turn and thus decreases the bicycle's energy. A) helps the bicycle accelerate inward to complete each turn without skidding.

In a soccer game, someone has kicked the ball so that it is heading right toward your face. You want to slow the ball down with your arm. To execute your plan most effectively you should

A) move your arm rapidly toward the oncoming ball. B) keep your arm still. C) move your arm in the direction that the ball is moving. D) move your arm slowly toward the oncoming ball. C) move your arm in the direction that the ball is moving.

When you drop a rubber ball on the floor and it bounces, the direction of its velocity reverses because

A) the ball can't stop moving and the floor blocks its path. B) the ball's momentum is conserved. C) the ball's energy is conserved. D) the floor exerts an upward support force on the ball and this force stops the ball's descent and eventually propels it upward. D) the floor exerts an upward support force on the ball and this force stops the ball's descent and eventually propels it upward.

Compared to planets close to the sun, and based upon Kepler's third law of planetary motion, the length of the year of planets farther out from the sun are

A) the same B) less C) larger D) more information is necessary. C) larger

You are watching a semi truck bounce up and down on a spring. At the topmost point in the truck's path,

A) the truck's velocity is downward but its acceleration is upward. B) the truck's velocity is zero but its acceleration is upward. C) the truck's velocity is upward but its acceleration is downward. D) the truck's velocity is zero but its acceleration is downward. D) the truck's velocity is zero but its acceleration is downward.

The spin cycle in your washing machine partially dries clothes by spinning them in a perforated metal basket. Such a process works because

A) the water leaves the basket moving tangent to the circular path B) the water is forced directly outward from the basket C) the water is drawn to the center of the basket D) the water is drained by gravity out the bottom of the basket. A) the water leaves the basket moving tangent to the circular path

Suppose you have an aquarium and you notice that you have a solid plastic decoration and a rock of about the same volume but twice as dense, and both are totally submerged in the water. The buoyant force on the plastic object is about ___________as that on the rock.

A) twice as big. B) the same. C) half as big. D) one quarter as big. B) the same.

The car is moving at 10 m/s relative to Bill. How fast does Amy see the car as moving?

A. 5 m/s B. 10 m/s C. 15 m/s D. 20 m/s C. 15 m/s

If the mass of one planet is somehow doubled, the force of gravity between it and a neighboring planet would

A. doubles. B. quadruples. C. reduces by half. D. reduces by one quarter. A. doubles.

If the distance between planets is somehow doubled, the force of gravity between them would

A. doubles. B. quadruples. C. reduces by half. D. reduces by one quarter. D. reduces by one quarter.

A "bouncy" or "lively" ball bounces higher from a rigid, immovable surface than a "dead" ball does because the "bouncy" ball

A. pushes harder on the surface B. transfers less energy to the surface C. returns more collision energy as rebound energy D. obtains more rebound energy from the surface C. returns more collision energy as rebound energy