1. Momentum may be expressed in:
 A. kg/m
 B. gram×s
 C. N×s
 D. kg/(m×s)
 E. N/s

2. Two bodies, A and B, have equal kinetic energies. The mass of A is nine times that of B. The ratio of the momentum of A to that of B is:
 A. 1:9
 B. 1:3
 C. 1:1
 D. 3:1
 E. 9:1

3. Which of the following five objects requires the greatest change in momentum to stop moving?
 A. object = electron, mass = 10–30 kg, speed = 107 m/s
 B. object = oil tanker, mass = 108 kg, speed = 10–1 m/s
 C. object = rain drop, mass = 10–4 kg, speed = 10 m/s
 D. object = snail, mass = 10–2 kg, speed = 10–4 m/s
 E. object = satellite, mass = 10 kg, speed = 104 m/s

4.

A particle moves along the x axis. Its momentum is graphed below as a function of time. Rank the numbered regions according to the magnitude of the force acting on the particle, least to greatest. A. 1, 2, 3, 4
 B. 2, 3, 4, 1
 C. 1, 4, 3, 2
 D. 1, 3, 4, 2
 E. 2, 4, 3, 1

5. A 0.20 kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30 m/s and rebounds at 20 m/s. The change in momentum of the ball as a result of the collision with the sidewalk is (in kg×m/s):
 A. 10
 B. 6
 C. 4
 D. 2
 E. 1

6. A rifle of mass M is initially at rest but free to recoil. It fires a bullet of mass m and velocity v (relative to the ground). After firing, the velocity of the rifle (relative to the ground) is:
 A. –mv
 B. –Mv/m
 C. –mv/M
 D. –v
 E. mv/M

7.

A 5-kg object can move along the x axis. It is subjected to a force ¢ in the positive x direction; a graph of F as a function of time t is shown below. Over the time the force is applied the change in the velocity of the object is: A. 0.8 m/s
 B. 1.1 m/s
 C. 1.6 m/s
 D. 2.3 m/s
 E. 4.0 m/s

8. Force:
 A. equals the negative integral (with respect to distance) of the potential energy function
 B. is the ability to do work
 C. is the rate of change of doing work
 D. equals the time rate of change of momentum
 E. has dimensions of momentum multiplied by time

9.

A 500-kg sack of coal is dropped on a 2000-kg railroad flatcar which was initially moving at 3 m/s as shown. After the sack rests on the flatcar, the speed of the flatcar is: A. 0.6 m/s
 B. 1.2 m/s
 C. 1.8 m/s
 D. 2.4 m/s
 E. 3.6 m/s

10. Why does a rocket accelerate when it is fired horizontally?
 A. Exhaust gases push against outside air
 B. Exhaust gases, which the rocket pushes backwards, push the rocket forward
 C. Outside air exerts more force on the back of the rocket than on the front
 D. Exhaust speed is greater than the rocket speed
 E. Atmospheric pressure at the back of the rocket is reduced

11. The law of conservation of momentum applies to a system of colliding objects only if:
 A. there is no change in kinetic energy of the system
 B. the coefficient of restitution is one
 C. the coefficient of restitution is zero
 D. the net external impulse is zero
 E. the collisions are all elastic

12. Sphere X, of mass 2 kg, is moving to the right at 10 m/s. Sphere Y, of mass 4 kg, is moving to the left at 10 m/s. The two spheres collide head-on. The ratio of the magnitude of the impulse exerted by X on Y to that exerted by Y on X is:
 A. 1/4
 B. 1/2
 C. D. 1
 E. need to know whether the collision is elastic or inelastic

13. An inelastic collision is one in which:
 A. momentum is not conserved but kinetic energy is conserved
 B. total mass is not conserved but momentum is conserved
 C. neither kinetic energy nor momentum is conserved
 D. momentum is conserved but kinetic energy is not conserved
 E. the total impulse is equal to the change in kinetic energy

14. Two spacemen are floating together with zero speed in a gravity-free region of space. The mass of spaceman A is 120 kg and that of spaceman B is 90 kg. Spaceman A pushes B away from him with B attaining a final speed of 0.5 m/s. The final recoil speed of A is:
 A. zero
 B. 0.38 m/s
 C. 0.5 m/s
 D. 0.67 m/s
 E. 1.0 m/s

15. Object A strikes the stationary object B head-on in an elastic collision. The mass of A is fixed, you may choose the mass of B appropriately. Then:
 A. for B to have the greatest recoil speed, choose mA = mB
 B. for B to have the greatest recoil momentum, choose mB << mA
 C. for B to have the greatest recoil kinetic energy, choose mB >> mA
 D. for B to have the least recoil speed, choose mB = mA
 E. for B to have the greatest recoil kinetic energy, choose mB = mA This is the end of the test. When you have completed all the questions and reviewed your answers, press the button below to grade the test.