physics exam 3

In an inelastic collision involving an isolated system, the final total momentum is a. exactly the same as the initial momentum b. more than the initial momentum c. less than the initial momentum d. not enough information to determin

a. exactly the same as the initial momentum

Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe's ball will be a. four times that of bill's ball b. two times that of bill's ball c. equal to that of bill's ball d. roughly 1.4 times that of bill's ball

a. four times that of bill's ball

As a spring is stretched a greater distance, the force of the spring on your hand a. increases b. decreases c. stays the same d. there is not enough information to tell

a. increases

a rubber ball bounces off a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. as a result of this bounce, which of the following quantities of the ball are conserved? a. kinetic energy of the ball b. momentum of the ball c. both the momentum and the kinetic energy of the ball d. none of the above quantities are conserved

a. kinetic energy of the ball

A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change? a. the ball b. the clay c. both of them experience the same non-zero momentum change d. both of them experience zero momentum change

a. the ball

a 5 kg ball collides inelastically head-on with a 10 kg ball, which is initially stationary. which of the following statements is true? a. the magnitude of the change of velocity the 5 kg ball experiences is greater than that of the 10 kg ball b. The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10-kg ball. c. The magnitude of the change of velocity the 5-kg ball experiences is equal to that of the 10-kg ball. d. The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball. e. Both balls lose all their momentum since the collision is inelastic.

a. the magnitude of the change of velocity the 5 kg ball experiences is greater than that of the 10 kg ball d. The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball.

a merry-go-round spins freely when diego moves quickly to the center along a radius of the merry-go-round. as he does this, it is true to say that a. the moment of inertia of the system decreases and the angular speed increases. b. the moment of inertia of the system decreases and the angular speed decreases. c. the moment of inertia of the system decreases and the angular speed remains the same. d. the moment of inertia of the system increases and the angular speed increases. e. the moment of inertia of the system increases and the angular speed decreases.

a. the moment of inertia of the system decreases and the angular speed increases.

When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice as much kinetic energy? a. square root of 2H b. 2H c. 4H d. 8H e. 16H

b. 2H

When water at 0°C freezes, the entropy of the water a. increases b. decreases c. remains constant d. could either increase or decrease, it depends on other factors

b. decreases

you are standing on a skateboard, initially at rest. a friend throws a very heavy ball towards you. you have 2 choices about what to do with the ball; either catch the ball or deflect it back toward your friend with the same speed as it was originally thrown. what choice should you make in order to maximize your speed on the skateboard? a. catch the ball b. deflect the ball back c. your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball.

b. deflect the ball back

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground a. both will have the same kinetic energy b. the heavier one will have twice the kinetic energy of the lighter one c. the heavier one will have 4 times the kinetic energy of the lighter one d. the heavier one will have half the kinetic energy of the lighter one e. the heavier one with have 1/4 the kinetic energy of the lighter one

b. the heavier one will have twice the kinetic energy of the lighter one

A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct? a. the ball had the same momentum just before and just after the bounce b. the magnitude of the ball's momentum was the same just before and just after the bounce c. the ball's momentum was conserved during the bounce d. none of the above statements are correct

b. the magnitude of the ball's momentum was the same just before and just after the bounce

a croquet mallet balances when suspended from its center of mass. if you cut the mallet into two pieces at its center of mass, how do the masses of the two pieces compare? a. the masses are equal b. the piece with the head of the mallet has the greater mass c. the piece with the head of the mallet has the smaller mass d. it is impossible to tell

b. the piece with the head of the mallet has the greater mass

Which two temperature changes are equivalent? a. 1 K = 1 F b. 1 F = 1 C c. 1 C = 1 K d. none of the above

c. 1 C = 1 K

a tiger is running in a straight line. if we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor? a. square root of 2 b. 2 c. 4 d. 8 e. 16

c. 4

When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice speed? a. square root of 2H b. 2H c. 4H d. 8H e. 16H

c. 4H

You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down. a. The work is positive on the way up and positive on the way down. b. The work is positive on the way up and negative on the way down. c. The work is negative on the way up and positive on the way down. d. The work is negative on the way up and on the way down because gravity is always downward

c. The work is negative on the way up and positive on the way down.

what conditions are necessary for an object to be in static equilibrium? a. sum of all the forces = 0 b. sum of all the torques = 0 c. both a and b d. none of the above

c. both a and b

a large 75 kg lighting fixture can be hung from wires of identical size and shape made of aluminum, brass, or copper. the values of young's modulus for these metals are 0.70 x 10^11 (aluminum), 0.91 x 10^11 (brass), and 1.1 x10^11 (copper). which wire would stretch the least distance? a. aluminum b. brass c. copper d. they will stretch the same distance

c. copper

Two wires are made out of the same metal, but one wire is twice as long as the other wire. Which wire will have the greatest elastic modulus? a. the shorter wire b. the longer wire c. it will be the same for both wires

c. it will be the same for both wires

a 25 kg piece of equipment can be hung by steel wires of length 1 m, 2 m, or 3 m. if all the wires have the same diameter, which one will stretch the greatest distance? a. the 1 m wire b. the 2 m wire c. the 3 m wire d. they will all stretch by the same distance

c. the 3 m wire

isabella does twice as much work as perry does and in half the time. isabella's power output is a. the same as perry's output b. one half as much as perry's power output c. twice perry's power output d. 1/4 perry's power output e. four times perry's power output

c. twice perry's power output

the temperature in your classroom is closest to a. 68 K b. 68 C c. 50 C d. 295 K

d. 295 K

You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top. a. It is impossible to tell since the times you both took are unknown. b. It is impossible to tell since the distances you both traveled are unknown. c. Your friend's gravitational potential energy is greater than yours because he got to the top faster. d. Both of you have the same amount of gravitational potential energy at the top. e. Your gravitational potential energy is greater than that of your friend because you traveled a greater distance in getting to the top.

d. Both of you have the same amount of gravitational potential energy at the top.

Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct? a. both do positive work, but person X does four times the work of person Y b. both do positive work, but person X does twice the work of person Y c. both do the same amount of positive work d. both do zero work e. both do positive work, but person X does 1/2 the work of person Y

d. both do zero work

a stone is held at a height (h) above the ground. a second stone with 4 times the mass of the first one is held at the same height. the gravitational potential energy of the second stone compared to that of the first stone is a. 1/4 as much b. 1/2 as much c. twice as much d. four times as much e. the same

d. four times as much

Candace sits on a freely spinning lab stool that has no friction in its axle. When she extends her arms, a. her moment of inertia decreases, and her angular speed increases. b. her moment of inertia decreases and her angular speed decreases. c. her moment of inertia increases and her angular speed increases. d. her moment of inertia increases and her angular speed decreases. e. her moment of inertia increases and her angular speed remains the same.

d. her moment of inertia increases and her angular speed decreases.

If the units of your answer are kg•m2/s3, which of the following types of quantities could your answer be? (There could be more than one correct choice.) a. kinetic energy b. potential energy c. force d. power e. work

d. power

When a car is weighed, it is driven slowly on a horizontal floor over a scale that records a reading as the front wheels go over the scale, and then records a second reading as the rear wheels go over the scale. The weight of the car is equal to a. the weight under the front wheels b. the weight under the rear wheels c. the average of the two weights d. the sum of the two weights e. the difference of the two weights

d. the sum of the two weights

Jeremy stands on the edge of a cliff. He throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. If the ground at the base of the cliff is level, which rock hits the ground with the greatest speed if there is no air resistance? a. rock X b. rock Y c. rock Z d. they all hit the ground with the same speed e. more information is needed

d. they all hit the ground with the same speed

which of the following is a true statement? a. the second law of thermodynamics is a consequence of the first law of thermodynamics b. it is possible for heat to flow spontaneously from a hot body to a cold one or from a cold one to a hot one, depending on whether or not the process is reversible or irreversible c. it is not possible to convert work entirely to heat d. it is impossible to transfer heat from a cooler to a hotter body e. all statements are false

e. all statements are false

Ferb and Phineas, push against a car that has stalled, trying unsuccessfully to get it moving. Phineas stops after 10 min, while Ferb is able to push for 5.0 min longer. Compare the work they do on the car. a. Ferb does 75% more work than Phineas b. Ferb does 50% more work than Phineas c. Phineas does 50% more work than ferb d. Ferb does 25% more work than Phineas e. neither of them does any work

e. neither of them does any work

a small car meshes with a large truck in a head-on collision. which of the following statements concerning the momentum during the collision are correct? a. the momentum of the truck is conserved b. the momentum of the car is conserved c. the car and the truck must undergo the same change in speed d. the momentum of the car and the momentum of the truck are each conserved e. the momentum of the car-truck system is conserved, but the momentum of each one separately is not conserved

e. the momentum of the car-truck system is conserved, but the momentum of each one separately is not conserved

a lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. they both slide up the same frictionless hill with no air resistance. what object rises to a greater height? a. the heavy object, because it has greater initial kinetic energy b. the light object, because gravity slows it down less c. the lightweight object because the force of gravity on it is less d. the heavy object because it has more mass to carry it up the hill e. they both slide to exactly the same height

e. they both slide to exactly the same height