Momentum Multiple Choice
1. The SI unit of momentum is which of the following? a) N ˙ m b) N/s c) N ˙ s = change of momentum = Force * time = impulse d) N/m
2. What is the momentum of a 2000 kg truck traveling at 20 m/s? a) 1.0X10
2 kg ˙ m/s b) 2.0X10
4 kg ˙ m/s c) 4.0X10
4 kg ˙ m/s = 2000kg 20 m/s = mv = p d) 4.0X10
5 kg ˙ m/s
3. if you pitch a baseball with twice the kinetic energy you gave it in the previous pitch, the magnitude of its momentum is a) the same. K=1/2 mv 2 = ½ m (1.41m/s) 2 = 2x b) 1.41 times as much.
p= mv = m(1.41m/s) = 1.41 x c) doubled. d) 4 times as much.
4. If the momentum of an object is doubled, by what factor will its kinetic energy change? a) 2 b) 4 p=mv = m2v k = ½ mv 2 k= ½ m(2v) 2 = 4 c) 1/2 d) 1/4
5. 060-kg tennis ball, initially moving at a speed of 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in momentum of the ball? a) 0.36 kg ˙ m/s = b) 0.72 kg ˙ m/s c) 1.1 kg ˙ m/s d) 1.8 kg ˙ m/s = p= mv
– mv o
m(v-v o
) = .060 kg ( -18m/s
– 12 m/s)
6. A 100-kg football linebacker moving at 2.0 m/s tackles head-on an 80-kg halfback running 3.0 m/s.
Neglecting the effects due to digging in of cleats, a) the linebacker will drive the halfback backward. b) the halfback will drive the linebacker backward. 80kg*3 m/s > 100kg *2 m/s c) neither player will drive the other backward. d) this is a simple example of an elastic collision.
7. A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force is correct? a) The truck experiences the greater average force. b) The small car experiences the greater average force. c) The small car and the truck experience the same average force. d) It is impossible to tell since the masses and velocities are not given.

8. A 50-kg pitching machine (excluding the baseball) is placed on a frozen pond. The machine fires a
0.40-kg baseball with a speed of 35 m/s in the horizontal friction. What is the recoil speed of the pitching machine? (Assume negligible friction.) a) 0.14 m/ s 0 = .40 kg (35 m/s) + 50 kg ( x ) b) 0.28 m/s c) 0.70 m/s d) 4.4X10
3 m/s
9. Two objects collide and stick together. Linear momentum a) is definitely conserved. b) is definitely not conserved. c) is conserved only if the collision is elastic. d) is conserved only if the environment is frictionless.
10. A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is correct? a) The total momentum both before and after the collision is 24 kg ˙ m/s. b) The total momentum before the collison is 24 kg ˙ m/s, and after the collision is 0 kg ˙ m/s. c) The total momentum both before and after the collision is zero. d) None of the above is true.
11. A bullet moving at 300 m/s is fired into a 1.00-kg block. The bullet emerges (the bullet does not embedded in the block) with half of its original speed. What is the velocity of the block right after the collision? You need to know the mass of the bullet a) 1.50 m/s m b
300 = m b
150 m/s + 1 kg v ow b) 2.97 m/s c) 3.00 m/s d) 273 m/s
12. A small object collides with a large object and sticks. Which object experiences the larger magnitude of momentum change? a) the large object b) the small object c) Both objects experience the same magnitude of momentum change. d) Cannot be determined from the information given.
13. Two astronauts, of masses 60 kg and 80 kg, are initially at rest in outer space. They push each other apart. What is their separation after the lighter astronaut has moved 12 m? a) 15 m b) 18 m c) 21 m 60kg ( 12m/ t) = 80 kg (d/t) 60 kg (12 m) = 80 kg (d ) d = 9 m d) 24 m Separation = 12 m + 9 m = 21m
14. When a cannon fires a cannonball, the cannon will recoil backward because the a) energy of the cannonball and cannon is conserved. b) momentum of the cannonball and cannon is conserved . c) energy of the cannon is greater than the energy of the cannonball. d) momentum of the cannon is greater than the energy of the cannonball.

15. A 1000-kg car traveling at 25 m/s runs into the rear of a stopped car that has a mass of 1500 kg and they stick together. What is the speed of the cars after the collision? a) 5.0 m/s 1000kg (25m/s) 10 m/s = b) 10 m/s ( 1000kg + 1500kg) c) 15 m/s d) 20 m/s
16. A rubber ball and a lump of putty 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 putty sticks to the wall. Which objects experiences the greater momentum change? a) the ball p= m(v-v o
) p =m ( - v o
- v o
) = - 2 mv o
ball b) the putty p= m(v-v o
) p =m ( 0 - v o
) = - 1 mv o
putty c) Both experience the same momentum change. d) Cannot be determined from the information given.
17. A constant 6.0-N net force acts for 4.0 s on a 12 kg object. What is the object's change of velocity? a) 2.0 m/s
 p = F
 t
 p = 6 N ( 4 s ) = 24 Ns 24 Ns = mv b) 12 m/s 24 Ns = 2.0m/s c) 18 m/s 12kg d) 288 m/s
18. The area under the curve on a Force versus time (F vs. t) graph represents a) impulse. b) momentum. c) work. d) kinetic energy.
19. A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-
Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision? a) Neither; both experienced the same magnitude impulse.-NEWTONS THIRD LAW b) the Ping-Pong ball c) the bowling ball d) It's impossible to tell since the velocities after the collision are unknown.
20. In an elastic collision, if the momentum is conserved, then which of the following statements is true about kinetic energy? a) kinetic energy is also conserved. b) kinetic energy is gained. c) kinetic energy is lost. d) none of the above.
21. When is kinetic energy conserved? a) in elastic collisions b) in inelastic collisions c) in any collison in which the objects do not stick together d) in all collisions

22. A rubber ball with a speed of 5.0 m/s collides head-on elastically with an identical ball at rest. What is the speed of the initially stopped ball after the collision? a) zero b) 1.0 m/s c) 2.5 m/s d) 5.0 m/s 1 st ball with stop
23. A 50 – gram moving +10 m/s collides head-on with a stationary ball of mass 100 g. The collision is elastic. What is the speed of each ball immediately after the collision? a) -3.3 m/s and +6.7 m/s b) +3.3 m/s and -6.7 m/s c) -6.7 m/s and +3.3 m/s d) +6.7 m/s and -3.3 m/s
.050kg (10m/s) = .5 kg m/s = p o
p = .050kg(-6.7m/s) + .100Kg (3.3 m/s) = .5kg m/s
24. 3.0-kg object moves to the right with a speed of 4.0 m/s. It collides in a perfectly elastic collision with a 6.0-kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision? a) 72 J b) 36 J ½ 3kg (4m/s) 2 + ½ 6 kg ( 2.0 m/s) 2 = 36 J c) 24 J d) 0 J
25. A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car? a) It increases. b) It remains the same. c) It decreases. p = mv If m goes up than v will decrease d) Cannot be determined from the information given.
College Prep Momentum Pre-test p= mv K.E. = ½ mv 2 F  t =  p
26.
A projectile’s speed and mass are doubled. Its momentum will then be a) doubled b) unchanged c) quadrupled d) halved e) quartered p = 2 m 2 v = 4 mv
m v mv
27.
A projectile’s speed and mass are doubled. Its kinetic energy will then a) b) increase by 2x remain unchanged
K.E= ½ (2m) (2v) 2 = 8x
½ (m) (v) 2 c) increase by 4x d) increase by 6x e) increase by 8x

28.
An object in motion must have
I. Acceleration II. Momentum may have a) I only
will have b) II only c) I and II d) I and III e) I, II and III
III. Potential Energy
may develop
29.
An explosion occurs in space. a) the kinetic energy of all of the fragments remains constant b) the total kinetic energy of the fragments decrease c) the total momentum of all the fragments remains constant d) the total momentum of the fragments decrease e) none of the above
30.
While floating motionlessly in a space station a 50 kg women pushes a 100 kg man. He sails away at 1.0 m/s and she
0 kg m/s = 100 kg (1.0m/s) + 50 ( -2.0m/s) a) remains motionless b) moves in the opposite direction as the man at 2.0 m/s c) moves in the opposite direction as the man at 1.0 m/s d) moves in the same direction as the man at 2.0 m/s e) moves in the same direction as the man at 1.0 m/s
31.
While floating motionlessly in a space station a 50 kg women pushes a 100 kg man. He sails away at 1.0 m/s. Which of the following is true? Newtons third law a) The force the women puts on the man is greater than the force the man puts on the woman b) The force the women puts on the man is less than the force the man puts on the woman c) The force the women puts on the man is equal to the force the man puts on the woman d) The force the women puts on the man depends on the center of mass of the woman and the man

32.
While floating motionlessly in a space station a 50 kg women pushes a 100 kg man. He sails away at 1.0 m/s. Which of the following is true? a) The change in momentum of the women is greater than the man’s change in momentum b) The change in momentum of the women is less than the man’s change in momentum c) The change in momentum of the women is equal to the man’s change in momentum d) The change in momentum of the women is zero because the momentum is transferred to the man
If the change in momentum is the same then the impulse will also be the same
33.
A tank car coasting frictionlessly horizontally along the rails has a leak in its bottom and dribbles several thousand gallons of water onto the roadbed. In the process it a) speeds up b) slows down c) remains at the same speed d) loses momentum e) gains momentum
34.
An open railroad car filled with coal is coasting frictionlessly. A person on board starts throwing the coal horizontally backward straight off the car, one chunk at a time.
The car a) speeds up b) slows down c) travels at a constant speed d) speeds up and then slows down e) speeds up or slows down depending on the horizontal speed of the coal
35.
A can of whipped cream floating in space develops a hole in the bottom from which it squirts backward a mess of gas and cream at a constant speed with respect to the can. The can will a) accelerate forward (assuming the gas and cream are escaping) b) move forward at a constant speed c) remain at rest d) first speed up and then slow down when the gas runs out e) none of the above

36.
In an elastic collision in a closed system
1.
Kinetic energy is conserved
2.
Linear momentum is conserved
3.
Kinetic energy is lost a) I only b) II only c) III only d) I and II e) II and III
37.
A 100-kg pitching machine (excluding the baseball) is placed on a frozen pond.
The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal friction. What is the recoil speed of the pitching machine? (Assume negligible friction.) a) 0.14 m/s b) 0.28 m/s c) 0.70 m/s d) 4.4X10
3 m/s
Show your work to receive credit for this problem p o
= p
0 = m b
v b
+ m p
v p
0 kg m/s = .40 kg ( 35 m/s ) + ( 100 kg) ( v ) v = -.14 m/s velocity therefore a speed of .14 m/s
38.
A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving at - 4.0 m/s. Which statement is correct? a) The total momentum both before and after the collision is 12 kg˙m/s. b) The total momentum both before and after the collision is -12 kg˙m/s. c) The total momentum before the collison is +12 kg˙m/s, and after the collision is 0 kg˙m/s. d) The total momentum before the collison is -12 kg˙m/s, and after the collision is 0 kg˙m/s. e) The total momentum both before and after the collision is zero.
Show your work to receive credit for this problem p o
= m
1 v
1
+ m
2 v
2
3.0 kg ( 4.0 m/s ) + 6.0 kg ( - 4.0 m/s ) = - 12 kg m/s

39.
A 1000-kg car traveling at 50 m/s runs into the rear of a stopped car that has a mass of 1500 kg and they stick together. What is the speed of the cars after the collision? a) 5.0 m/s b) 10 m/s c) 15 m/s d) 20 m/s e) 25 m/s
Show your work in order to receive credit for this problem p o
= p
m c
v oc
= ( m c
+ m c2
) v
12 m c
v oc
= v
12
= 1000 kg ( 50 m/s) = 20 m/s
( m c
+ m c2
) (1000 kg + 1500 kg)
40.
A 50 kg moving +20 m/s collides head-on with a stationary ball of mass 100 kg.
The collision is elastic. What is the speed of each ball immediately after the collision? a) +6.7 m/s and -13.47 m/s b) -6.7 m/s and +13.47 m/s c) -6.7 m/s and +3.3 m/s d) +6.7 m/s and -3.3 m/s
Show your work in order to receive credit for this problem
Light onto heavy will cause the light to reverse direction and the heavy to move forward
Therefore a and d are not possible
50 kg ( 20 m/s ) = 50 kg ( v
1
) + 100 kg ( v
2
)
50 kg ( 20 m/s ) = 50 kg ( -6.7 m/s ) + 100 kg ( 13.47 m/s )
1000 Goodson = - 350 Goodson + 1350 Goodson
50 kg ( 20 m/s ) = 50 kg ( -6.7 m/s ) + 100 kg ( 3.3 m/s )

41.
What is the impulse of the following collision? Show your work.
Impulse = Area = ½ b h = ½ (.5s - .1s ) ( 10 N ) = 2 N s
Force as a function of time for the collision of a cart on a wall
12
10
8
6
4
2
0
-2
0
Series1
0.2
0.4
time in seconds
0.6
0.8
42.
What is the impulse of the following collision? Show your work.
Impulse = Area = ½ b h = ½ (.9s - .1s ) ( 5.0 N ) = 2 N s
Force as a function of time for the collision of a cart on a wall
4
3
2
1
6
5
Series1
0
-1
0 0.2
0.4
0.6
0.8
1 1.2
time in seconds
43. Which of the above collisions involves a larger average force and why?
Shorter Time – larger force
F =  p = 2 N s = 5 N
t (.5-.1 s)
Larger time – smaller force
F =  p = 2 N s = 2.5 N
(.9s-.1s)

43.
Using a ballistic pendulum what must be known in order to determine the original velocity
of the pendulum.
1) mass of bullet
2) mass of pendulum
3) change in height of pendulum/ball system v ob
= ( m b
+ m p
) 2 g h
m b
45.
What is conserved when a paint ball collides with the pendulum m b v ob
= ( m b
+ m p
) v bh v ob
= ( m b
+ m p
) v bh
m b a.
the momentum of the ball and the pendulum b.
the kinetic energy of the ball and pendulum c.
the momentum and kinetic energy of the ball and pendulum d.
neither the momentum or kinetic energy of the ball and pendulum
46.
What is conserved when a paint ball and pendulum swing to a maximum height. a.
the momentum of the ball and the pendulum b.
the energy of the ball and pendulum c.
the momentum and energy of the ball and pendulum d.
neither the momentum or energy of the ball and pendulum
½ ( m b
+ m p
) v bp
2 = ( m b
+ m p
) g h
½ v bp
2 = g h v bp
2 = 2 g h v bp
= 2 g h v ob
= ( m b
+ m p
) 2 g h
m b