TEST 3 - CONCEPTUAL

ANS: B PTS: 1 DIF: 2

12. A rock is moving with speed v. If the mass of the rock were tripled and the speed were reduced to v/3, which of the following statements would be true? a. The kinetic energy of the rock is smaller than in the first case, but the momentum is larger. b. The kinetic energy of the rock is smaller than in the first case, but the momenta of both are the same. c. The kinetic energies of the rocks are the same in both cases. d. The kinetic energy of the rock is 1/9 its previous value.

ANS: C PTS: 1 DIF: 2

20. If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the paper out without disturbing the glass very much if the pull is done very quickly. This is because with a quick pull: a. the force on the glass will be less. b. the momentum of the paper will be greater. c. the time for the pull will be less. d. the coefficient of kinetic friction will be less.

ANS: D

20. When an object is dropped from a tower, what is the effect of the air resistance as it falls? a.It does positive work. b. It increases the object's kinetic energy. c. It increases the object's potential energy. d. None of the above choices are valid.

ANS: C

21. Two blocks are released from the top of a building. One falls straight down while the other slides down a smooth ramp. If all friction is ignored, which one is moving faster when it reaches the bottom? a. The block that went straight down. b. The block that went down the ramp. c. They both will have the same speed. d. Insufficient information to work the problem.

ANS: D

22. Is it possible for the total mechanical energy of a moving particle to be negative? a.No, because a moving particle has positive kinetic energy. b.No, because potential energy cannot have a value more negative than the value of the positive kinetic energy of the particle. c. Only if friction is involved. d.Yes

ANS: C PTS: 1 DIF: 1

22. The units of impulse are equivalent to: a. those of energy. c. kg·m/s. b. N·s. d. those of force.

ANS: C PTS: 1 DIF: 1

23. A moderate force will break an egg. However, an egg dropped on the road usually breaks, while one dropped on the grass usually doesn't break. This is because for the egg dropped on the grass: a. the change in momentum is greater. c. the time interval for stopping is greater. b. the change in momentum is less. d. the time interval for stopping is less.

ANS: B

23. Three different-mass projectiles are launched at different angles of elevation from the top of a building. Each particle has the same initial kinetic energy. Which particle has the greatest kinetic energy just as it impacts with the ground? a. The one launched at the highest angle of elevation. b. The one with the highest mass. c. The one with the lowest mass. d. They all will have the same kinetic energy on impact.

ANS: C

24. Three different-mass projectiles are launched at different angles of elevation from the top of a building. Each particle has the same initial kinetic energy. Which particle has the greatest speed just as it impacts with the ground? a. The one launched at the highest angle of elevation. b. The one with the highest mass. c. The one with the lowest mass. d. They all will have the same speed on impact.

ANS: D

25. In a problem using energy considerations to solve for the speed of a ball thrown from the top of a building when it strikes the ground below, where should the potential energy have its zero value? a. It should be at the level from where the ball is thrown. b. It should be at the ground level where the ball hits. c. It should be slightly below ground level so the potential energy is always positive. d. It doesn't matter since only differences in potential energy matter in solutions.

ANS: D

26. Which of the following is not true about potential energy? a. Potential energy is stored energy. b. Potential energy is related to position. c. Potential energy is a scalar quantity. d. Potential energy has direction.

ANS: A PTS: 1 DIF: 2

28. Two masses m1 and m2, with m1 = 3 m2, undergo a head-on elastic collision. If the particles were approaching with speed v before the collision, with what speed are they moving apart after collision? a. v c. 3v/4 b. v/3 d. 3v

Answer: FALSE Var: 1

3) As a tile falls from the roof of a building to the ground its momentum is conserved.TF

Answer: C Var: 1

3) In the figure, determine the character of the collision. The masses of the blocks, and the veloc-ities before and after are given. The collision is: A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) characterized by an increase in kinetic energy. E) not possible because momentum is not conserved.

Answer: TRUE

3) Kinetic energy is conserved only in perfectly elastic collisions, but momentum is conserved in all collisions.TF

ANS: B

3. The area under the force-displacement curve represents: a. area. b. work. c. force. d. coefficient of static friction.

ANS: A PTS: 1 DIF: 1

3. The dimensional equivalence of the quantity "momentum" in terms of the fundamental quantities (mass, length, time) is: a. MLT1. c. MLT. b. ML2T2. d. MLT2.

ANS: D PTS: 1 DIF: 1

30. The law of conservation of momentum is applicable to systems made up of objects described by which of the following? a. macroscopic c. interacting through friction b. microscopic d. All the above choices are valid.

ANS: B PTS: 1 DIF: 1

10. The kinetic energy of an object is quadrupled. Its momentum will change by what factor? a. zero c. eight b. two d. four

ANS: C

11. A golf ball hits a wall and bounces back at 3/4 the original speed. What part of the original kinetic energy of the ball did it lose in the collision? a.1/4 c. 7/16 b. 3/8 d. 9/16

ANS: C PTS: 1 DIF: 3

11. Object 1 has twice the mass of Object 2. Each of the objects has the same magnitude of momentum. Which of the following statements is true? a. Both objects can have the same kinetic energy. b. One object has 0.707 times the kinetic energy of the other. c. One object has twice the kinetic energy of the other. d. One object has 4 times the kinetic energy of the other.

ANS: D PTS: 1 DIF: 2

33. An object of mass m moving at speed v strikes and object of mass 2m which had been at rest. The first object bounces backward along its initial path at speed v. Is this collision elastic, and if not, what is the change in kinetic energy of the system? a. The collision is elastic. b. The kinetic energy decreases by mv2. c. The kinetic energy decreases by 1/2 mv2. d. The kinetic energy increases by mv2.

ANS: C PTS: 1 DIF: 2

34. A billiard ball is moving in the x direction at 30.0 cm/s and strikes another billiard ball moving in the y direction at 40.0 cm/s. As a result of the collision, the second ball moves at 50.0 cm/s, and the first ball stops. In what final direction does the second ball move? a. in the x direction b. at an angle of 45.0o ccw from the x direction c. at an angle of 53.1o ccw from the x direction d. Such a collision cannot happen.

ANS: C PTS: 1 DIF: 1

37. A billiard ball collides in an elastic head-on collision with a second stationary identical ball. After the collision which of the following conditions applies to the first ball? a. maintains the same velocity as before c. comes to rest b. has one-half its initial velocity d. moves in the opposite direction

ANS: A PTS: 1 DIF: 1

38. A billiard ball collides in an elastic head-on collision with a second identical ball. What is the kinetic energy of the system after the collision compared to that before collision? a. the same as c. twice b. one fourth d. four times

ANS: C PTS: 1 DIF: 1

39. In a two-body collision, if the momentum of the system is conserved, then which of the following best describes the kinetic energy after the collision? a. must be less c. may also be conserved b. must also be conserved d. is doubled in value

Answer: A Var: 1

4) In the figure, determine the character of the collision. The masses of the blocks, and the veloc-ities before and after are given. The collision is: A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) not possible because momentum is not conserved.

Answer: FALSE Var: 1

4) When a baseball player hits a home run, the baseball receives a greater impulse from the bat than the bat does from the ball.TF

Answer: FALSE

4) When a moving object hits a stationary object and causes it to move, some of the moving ob-ject's kinetic energy is transformed into momentum in the object that was at rest.TF

ANS: B

4. If both mass and velocity of a ball are doubled, the kinetic energy is increased by a factor of: a.16. b.8. c.4 d. 2.

ANS: B PTS: 1 DIF: 1

40. In a two-body collision, if the kinetic energy of the system is conserved, then which of the following best describes the momentum after the collision? a. must be less c. may also be conserved b. must also be conserved d. is doubled in value

ANS: B PTS: 1 DIF: 2

44. Two objects, one less massive than the other, collide elastically and bounce back after the collision. If the two originally had velocities that were equal in size but opposite in direction, then which one will be moving slower after the collision? a. The less massive one. b. The more massive one. c. The speeds will be the same after the collision. d. There is no way to be sure without the actual masses.

ANS: D PTS: 1 DIF: 2

47. Kaitlin uses a bat to hit a thrown baseball. She knocks the ball back in the direction from which it came in an inelastic collision. The bat, which is heavier than the baseball, continues to move in the same direction after the hit as Kaitlin "follows through." Is the ball moving faster before or after it was hit? a. The ball was moving faster before it was hit. b. The ball was moving faster after it was hit. c. The ball was moving at essentially the same speed before and after the hit. d. There is insufficient information to answer this problem.

ANS: C

47. The SI units for k, the spring constant, are equivalent to: a. J b.J / N c. kg / s2 d. none of the above

ANS: C PTS: 1 DIF: 2

48. A tennis ball is held above and in contact with a basketball, and then both are simultaneously dropped. The tennis ball bounces off the basketball at a fairly high speed. This is because: a. the basketball falls farther than the tennis ball. b. the tennis ball is slightly shielded from the Earth's gravitational pull. c. the massive basketball transfers momentum to the lighter tennis ball. d. the tennis ball has a smaller radius.

ANS: B

48. When a Hooke's law spring is stretched a distance 3x, how much is the increase in energy stored in it from when it was stretched a distance x? Give your answer in terms of a multiple of the energy stored in the spring when it is stretched a distance x. a. It is 3 times as much. b. It is 8 times as much. c. It is 4 times as much. d. It is 9 times as much.

ANS: A

49. A spring with spring constant k is used to launch a mass m up a frictionless inclined plane having angle of elevation . What is the maximum height reached above the starting elevation of the mass during the mo-tion of the mass if the spring is compressed a distance d before launch? a. c. b. d.

Answer: FALSE Var: 1

5) A shell explodes into two fragments, one 25 times heavier than the other. The momentum change of the lighter fragment is 25 times as great as the momentum change of the heavier fragment.TF

Answer: B Var: 1

5) During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a long barrel. What is the reason for using a long barrel in these guns? A) to reduce frictional losses B) to allow the force of the expanding gases from the gunpowder to act for a longer time C) to increase the force exerted on the bullet due to the expanding gases from the gunpowder D) to reduce the force exerted on the bullet due to the expanding gases from the gunpowder

Answer: FALSE

5) If a force acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy or momentum.TF

ANS: D

5. If during a given physical process the only force acting on an object is friction, which of the following must be assumed in regard to the object's kinetic energy? a. decreases c. remains constant b. increases d. cannot tell from the information given

ANS: D PTS: 1 DIF: 2

52. A 5-kg object is moving to the right at 4 m/s and collides with another object moving to the left at 5 m/s. The objects collide and stick together. After the collision, the combined object: a. is moving to the right. b. is moving to the left. c. is at rest. d. has less kinetic energy than the system had before the collision.

ANS: B PTS: 1 DIF: 1

53. In a system with two moving objects, when a collision occurs between the objects: a. the total kinetic energy is always conserved. b. the total momentum is always conserved. c. the total kinetic energy and total momentum are always conserved. d. neither the kinetic energy nor the momentum is conserved.

ANS: C PTS: 1 DIF: 1

56. When a collision is completely inelastic, then: a. all the kinetic energy is conserved. c. the participants stick together. b. all the kinetic energy is gone. d. the total momentum is zero.

ANS: D PTS: 1 DIF: 2

57. In a completely inelastic collision between two objects where the mass of one is double that of the other, which of the following statements is always true? a. The larger mass will always lose kinetic energy. b. The smaller mass will always gain kinetic energy. c. The momentum of the smaller mass will have a larger magnitude change than that of the larger mass. d. Not even one of the above statements is true.

ANS: C

57. Which of the following is an example of a nonconservative force? a. gravity c. friction b. the force from a Hooke's law spring d. Both choices A and B are valid.

ANS: B PTS: 1 DIF: 3

58. Three masses are moving along the x-axis. Their masses and velocities are: with , with , and with (the minus sign indicating this velocity is in the negative x-direction). The three masses collide and stick together in a completely inelastic collision. What is the resultant velocity of the combined mass? a. 0, since their combined momentum is zero. b. c. d.

ANS: D

58. Which of the following is that form of energy associated with an object's motion? a. potential c. bio-chemical b. thermal d. kinetic

ANS: A

59. Which of the following is that form of energy associated with an object's location in a conservative force field? a. potential c. bio-chemical b. thermal d. kinetic

Answer: TRUE

6) A 2.0 kg stone slides from rest down a hill 5.0 m high and is observed to be moving at 6.0 m/s at the bottom. During this process, 62 J of thermal energy have been produced.TF

Answer: FALSE Var: 1

6) A ball of clay is thrown against a wall and sticks there. In this process, momentum is not conserved because the clay stops moving.TF

Answer: C Var: 1

6) Consider two less-than-desirable options. In the first you are driving 30 mph and crash into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. Which of these two situations would re-sult in the greatest impact force? A) hitting the other car B) hitting the brick wall C) The force would be the same in both cases. D) We cannot answer this question without more information. E) None of these is true.

ANS: B

60. A Hooke's law spring is compressed a distance d and is used to launch a mass m vertically to a height h above its starting position. Under the same compression d, the spring is now used to launch a mass of 2m. How high does this second mass rise? a. h c. h/1.41 b. h/2 d. h/4

ANS: D PTS: 1 DIF: 2

60. Two masses collide and stick together. Before the collision, one of the masses was at rest. Is there a situation in which the kinetic energy is conserved in such a collision? a. Yes, if the less massive particle is the one initially at rest. b. Yes, if the more massive particle is the one initially at rest. c. Yes, if the two particles have the same mass. d. No, kinetic energy is always lost is such a collision.

ANS: D

61. A Hooke's law spring is compressed a distance d and is used to launch a mass m vertically to a height h above its starting position. Under double the compression, the spring is now used to launch the mass. How high does the mass now rise above its starting position? a. 2h c. 3h b. 1.41h d. 4h

ANS: D PTS: 1 DIF: 1

61. Two particles collide, one of them initially being at rest. Is it possible for both particles to be at rest after the collision? a. If the collision is perfectly inelastic, then this happens. b. If the collision is elastic, then this happens. c. This can happen sometimes if the more massive particle was at rest. d. No.

ANS: B

62. A Hooke's law spring is compressed a distance d and is used to launch a particle of mass m vertically to a height h above its starting position. Under double the compression, the spring is now used to launch a par-ticle of mass 2 m. How high does the second mass rise above its starting position? a. h c. 3h b. 2h d. 4h

ANS: C

63. A block is projected with speed v across a horizontal surface and slides to a stop due to friction. The same block is then projected with the same speed v up an incline where it slides to a stop due to friction. In which case did the total mechanical energy of the block decrease the least? a. This problem cannot be solved since it was not indicated whether the horizontal surface and the in-cline both had the same coefficient of kinetic friction. b. The case on the horizontal surface had the least decrease in total mechanical energy. c. The case on the inclined surface had the least decrease in total mechanical energy. d. In both cases the decrease in mechanical energy was the same.

ANS: B PTS: 1 DIF: 2

65. A lump of clay is thrown at a wall. A rubber ball of identical mass is thrown with the same speed toward the same wall. Which statement is true? a. The clay experiences a greater change in momentum than the ball. b. The ball experiences a greater change in momentum than the clay. c. The clay and the ball experience the same change in momentum. d. It is not possible to know which object has the greater change in momentum.

ANS: D PTS: 1 DIF: 2

66. Three satellites are launched into space connected together. Once in deep space, an explosive charge separates the three satellites and they move apart. The satellites each have different masses with m1 < m2 < m3. Which of the following statements is always true? a. The one with mass m1 receives the greatest impulse. b. The one with mass m3 receives the greatest impulse. c. The all must receive equal impulses. d. Although one or more of the above statements could be true in special cases, they are not always true.

Answer: TRUE

7) A 3.5 kg mass is pressed against a spring of spring constant 90.0 N/m, compressing it 25.0 cm. The greatest amount of kinetic energy this mass could gain after it is released is 2.81 J.TF

Answer: A Var: 1

7) A 5 kg ball collides head-on with a 10 kg ball, which is initially stationary. The collision is inelastic. Which statement 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) Two of the above statements are true.

Answer: A

7) A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown verti-cally downward. Assuming the elevation loss of the three rocks is the same (the base of the cliff is flat), which rock hits the ground with the highest speed? A) They all hit the ground with the same speed. B) Rock X C) Rock Y D) Rock Z

Answer: FALSE Var: 1

7) In a collision between a small car and a large truck, the car and the truck undergo the same change in their velocities.TF

ANS: B PTS: 1 DIF: 3

7. Object 1 has twice the mass of Object 2. Both objects have the same kinetic energy. Which of the following statements is true? a. Both objects can have the same magnitude of momentum. b. Object 1 has a momentum of greater magnitude than Object 2. c. The magnitude of the momentum of Object 2 is four times that of Object 1. d. All the statements are false.

ANS: B PTS: 1 DIF: 2

72. In an inelastic collision between two objects with unequal masses: a. the velocity of one will increase by the amount that the velocity of the other decreases. b. the momentum of one will increase by the amount that the momentum of the other decreases. c. the energy of one increases by the amount that the energy of the other decreases. d. the total momentum of the system will decrease.

ANS: C PTS: 1 DIF: 2

75. A 6-kg object is moving to the right at 4 m/s and collides with a 4-kg object moving to the left at 6 m/s. The objects collide and stick together. After the collision, the combined object: a. has the same kinetic energy that the system had before the collision. b. has more kinetic energy than the system had before the collision. c. has no kinetic energy. d. has less momentum than the system had before the collision.

ANS: A PTS: 1 DIF: 1

76. If a two-body collision is not head-on, then we may always assume that: a. momentum is conserved. b. kinetic energy is conserved. c. neither momentum nor kinetic energy are conserved. d. both momentum and kinetic energy are conserved.

ANS: C

76. The quantity of work equal to one joule is also equivalent to which of the following? a. watt c. watt s b. watt /s d. watt /s2

ANS: A PTS: 1 DIF: 2

77. A 70-kg man is standing in a 20-kg boat. Thinking he is stepping out onto the dock, the man steps to the right. However, the following will actually happen (ignore the friction of the water or air on the boat or the man): a. The man only moves a short distance to the right while the boat moves a larger distance to the left. b. The man actually stays still while the boat moves toward the left. c. The boat doesn't move and the man moves to the right. d. None of the above.

ANS: D

77. The rate at which work is done is equivalent to which of the following? a. increase in potential energy c. potential energy b. thermal energy d. power

ANS: B

78. The unit of power, watt, is dimensionally the same as: a. joule-second. c. joule-meter. b. joule/second. d. joule/meter.

ANS: B

79. A force of 5.0 N is applied to a 20-kg mass on a horizontal frictionless surface. As the speed of the mass increases at a constant acceleration, the power delivered to it by the force: a. remains the same. c. decreases. b. increases. d. doubles every 4.0 seconds.

Answer: FALSE

8) In a ballistics test, a bullet traveling horizontally strikes and embeds itself in a large block that is free to move. During this process, the bullet transfers all of its momentum to the block. TF

Answer: A

8) Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed of twice as high as Bill's ball. 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) eight times that of Bill's ball. E) roughly 1.3 times that of Bill's ball.

Answer: A

8) Two friends are standing on opposite ends of a canoe. The canoe is initially at rest with re-spect to the lake. The person on the right throws a very massive ball to the left, and the person on the left catches it. After the ball is caught (ignoring friction between the canoe and the water), the canoe is A) stationary. B) moving to the right. C) moving to the left.

ANS: A PTS: 1 DIF: 2

8. Two masses m1 and m2, with m1 > m2, have momenta with equal magnitudes. How do their kinetic energies compare? a. KE1 < KE2 c. KE1 > KE2 b. KE1 = KE2 d. More information is needed.

ANS: B PTS: 1 DIF: 2

80. Three masses are positioned along the x-axis. Their masses and positions are: with , with , and with . What is the x-coordinate of center of mass of this system? a. (14/3) m c. 2 m b. (7/3) m d. Not enough information is given to answer this question.

ANS: D PTS: 1 DIF: 2

82. A system of 3 masses is located as follows: at ( ), at the origin, and at ( ). Where is the center of mass of these masses? a. c. b. d.

ANS: C PTS: 1 DIF: 2

86. A model rocket sits on the launch pad until its fuel is ignited, blasting the rocket upward. During the short time of blast-off, as the ignited fuel goes down, the rocket goes up because: a. the fuel pushes on the ground. b. air friction pushes on the escaping fuel. c. the downward force of gravity on the rocket is less than the rate of downward momentum increase of the fuel. d. of none of the above reasons.

Answer: A

9) A ball can be rolled down one of four different ramps, as shown below. The final elevation loss of each of the ramps is the same. Neglecting friction, for which ramp will the speed of the ball be the highest at the bottom? A) The speed of the ball will be the same for all ramps. B) Ramp X C) Ramp Y D) Ramp Z

ANS: D PTS: 1 DIF: 1

9. If the momentum of an object is tripled, its kinetic energy will change by what factor? a. zero c. three b. one-third d. nine

ANS: D

A pendulum consists of a mass m suspended from a string of length L. When the pendulum is swinging, how much greater is the mass's potential energy when the string is displaced from the vertical by the angle than when the mass is at the lowest position? a. c. b. d.

Answer: FALSE Var: 1

1) A rubber ball moving horizontally at 8.50 m/s hits a brick wall and bounces back with exactly the same speed but in the opposite direction. During this collision, its change in momentum is zero.TF

Answer: TRUE

1) As a stone slides down a frictionless, ice-covered hill, its mechanical energy is conserved but its momentum is not conserved.TF

Answer: A Var: 1

1) Three cars, Car X, Car Y, and Car Z, begin accelerating from rest, at the same time. Car X is more massive than Car Y, which is more massive than Car Z. The net force exerted on each car is identical. After 10 seconds, which car has the most amount of momentum? A) They all have the same amount of momentum. B) Car X C) Car Y D) Car Z

ANS: C PTS: 1 DIF: 1

1. A valid unit for momentum is which of the following? a. kg m/s2 c. kg m/s b. kg/m2 d. N m

ANS: D

1. The unit of work, joule, is dimensionally the same as: a. newton/second. c. newton-second. b. newton/kilogram. d. newton-meter.

ANS: C PTS: 1 DIF: 2

13. In an automobile collision, how does an airbag lessen the blow to the passenger? Assume as a result of the collision, the passenger stops. a. The airbag decreases the momentum change of the passenger in the collision. b. During the collision, the force from the airbag is greater than the force from the windshield or dashboard, so the passenger cannot hit the hard objects. c. The stopping impulse is the same for either the hard objects or the airbag. Unlike the windshield or dashboard, the airbag gives some, increasing the time for the slowing process and thus decreasing the average force on the passenger. d. The airbag is there to ensure the seatbelt holds.

ANS: C PTS: 1 DIF: 1

14. The dimensional equivalent of the quantity impulse in terms of the fundamental quantities (mass, length, time) is which of the following? a. MLT c. MLT1 b. ML2T2 d. MLT2

Answer: A

16) Three cars (car F, car G, and car H) are moving with the same velocity, and slam on the brakes. The most massive car is car F, and the least massive is car H. Assuming all three cars have identical tires, which car travels the longest distance to skid to a stop? A) They all travel the same distance in stopping. B) Car F. C) Car G. D) Car H.

ANS: C PTS: 1 DIF: 1

16. The impulse experienced by a body is equivalent to its change in: a. velocity. c. momentum. b. kinetic energy. d. None of the other choices are valid.

Answer: A

18) A person drops one rock from rest and it falls 100 meters down a cliff before hitting the ground. The person then throws an identical rock downward. The amount of kinetic energy gained by the rock dropped from rest is _____ that of the second rock, and the magnitude of the change in speed (between hitting the ground and its initial speed) of the rock dropped from rest is _____ that of the second rock. A) equal to, greater than B) equal to, equal to C) less than, less than D) equal to, less than

ANS: B

19. As an object is lowered into a deep hole in the surface of the Earth, which of the following must be as-sumed in regard to its potential energy? a. It increases. b. It decreases. c. It remains constant. d. One cannot tell from the information given.

Answer: TRUE Var: 1

2) In a collision between a light hydrogen molecule and a heavy water molecule, the momentum lost by one molecule is exactly the same as the momentum gained by the other molecule.TF

Answer: FALSE

2) Two cars collide, lock bumpers, and eventually slide to a stop due to friction with the road-way. During this entire process, mechanical energy and momentum are both conserved.TF

Answer: B Var: 1

2) You are standing on a skateboard, initially at rest. A friend throws a very heavy ball toward you. You can either catch the object or deflect the object back toward your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do 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.

ANS: D

2. The work done by static friction can be: a. positive. b. negative. c. zero. d. Any of the above.