Question 1

A 60-kg swimmer dives from a 150-kg raft with a horizontal speed of 1.5 m/s. The raft is initially at rest. What is the speed of the raft immediately after the diver jumps?

Accepted Answer

The answer of A 60-kg swimmer dives from a 150-kg...

Question 2

A railroad car of mass m and speed v collides and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system

Accepted Answer

A)  is the same as before. 
B)  is half as much as before. 
C)  is one third as much as before. 
D)  is one fourth as much as before. 
E)  is one quarter as much as before.

Question 3

Internal forces cannot change the total kinetic energy of a system.

Accepted Answer

A) True 
 B)False

Question 4

A firecracker breaks up into two pieces, one has a mass of 200 g and flies off along the x-axis with a speed of 82.0 m/s and the second has a mass of 300 g and flies off along the y-axis with a speed of 45.0 m/s. What is the total momentum of the two pieces?

Accepted Answer

A)  361 kg∙m/s at 56.3° from the x-axis 
B)  93.5 kg∙m/s at 28.8° from the x-axis 
C)  21.2 kg∙m/s at 39.5° from the x-axis 
D)  361 kg∙m/s at 0.983° from the x-axis 
E)  21.2 kg∙m/s at 56.3° from the x-axis

Question 5

A batter applies an average force of 8000 N to a baseball for 1.10 ms. What is the magnitude of the impulse delivered to the baseball?

Accepted Answer

The answer of A batter applies an average force of...

Question 6

A ping-pong ball originally at rest is hit head-on by a bowling ball moving with initial speed v0. It is given that the mass of the ping-pong ball is as good as negligible in comparison with the mass of the bowling ball. What is the speed of the ping-pong ball after this elastic collision?

Accepted Answer

A)   
B)  v0 
C)  2v0 
D)  4v0 
E)  8v0

Question 7

In the two-dimensional elastic collision of a particle with a stationary particle that has the same mass, the trajectories of the two particles after the collision are at right angles to each other. Explain why this should be so.

Accepted Answer

The answer of In the two-dimensional elastic collision of a...

Question 8

A 1200-kg pick-up truck traveling south at 15.0 m/s collides with a 750-kg car traveling east. The two vehicles stick together. A patrolman investigating the accident determines that the final position of the wreckage after the collision is 25.0 m, at an angle of 50.0° south of east, from the point of impact. He also determines that the coefficient of friction between the tires and the road at that location was 0.400. What was the speed of the car before the collision?

Accepted Answer

A)  19.6 m/s 
B)  4.84 m/s 
C)  14.0 m/s 
D)  23.4 m/s 
E)  17.4 m/s

Question 9

A golf club exerts an average force of 1000 N on a 0.045-kg golf ball which is initially at rest. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball as it leaves the tee?

Accepted Answer

A)  30 m/s 
B)  35 m/s 
C)  40 m/s 
D)  45 m/s 
E)  50 m/s

Question 10

A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together. In what direction does the wreckage move just after the collision?

Accepted Answer

A)  36.9° N of E 
B)  42.0° N of E 
C)  45.0° N of E 
D)  53.1° N of E 
E)  48.0° N of E

Question 11

A 0.330-kg volleyball is thrown vertically downward with a speed of 0.150 m/s. It takes it 0.0655 s to reach the ground. What is the magnitude of its momentum just before it hits the ground?

Accepted Answer

A)  0.212 kg∙m/s 
B)  0.262 kg∙m/s 
C)  0.163 kg∙m/s 
D)  0.0216 kg∙m/s 
E)  0.0418 kg∙m/s

Question 12

A system that has zero momentum must also have zero kinetic energy.

Accepted Answer

A) True 
 B)False

Question 13

An 80.0-g puck moving at 1.20 m/s on an air table collides with a stationary 100-g puck. After the collision, the 80.0-g puck moves in a direction that makes an angle of 45.0° with the original direction of motion and the 100-g puck moves at an angle of 12.0° in the opposite direction. What is the speed of the 80.0-g puck after the collision?

Accepted Answer

A)  0.809 m/s 
B)  0.297 m/s 
C)  0.533 m/s 
D)  0.0953 m/s 
E)  1.23 m/s

Question 14

A rope is lying on a table. You pick up one end and start raising it with a constant velocity. The force you have to exert on the rope is

Accepted Answer

A)  equal to the weight of the portion of the rope that is not on the table. 
B)  greater than the weight of the portion of the rope that is not on the table. 
C)  less than the weight of the portion of the rope that is not on the table but not zero N. 
D)  zero N. 
E)  Cannot be determined without additional information.

Question 15

A batter hits a 0.140-kg baseball that was approaching him at 40.0 m/s and, as a result, the ball leaves the bat at 30.0 m/s in the direction of the pitcher. What is the magnitude of the impulse delivered to the baseball?

Accepted Answer

A)  9.80 Ns 
B)  1.40 Ns 
C)  5.60 Ns 
D)  4.90 Ns 
E)  7.00 Ns

Question 16

A 60.0-kg man stands at one end of a 20.0-kg uniform 10.0-m long board. How far from the man is the center of mass of the man-board system?

Accepted Answer

A)  1.25 m 
B)  2.50 m 
C)  5.00 m 
D)  7.50 m 
E)  9.00 m

Question 17

What is the magnitude of the momentum of a 0.140 kg baseball traveling at 45.0 m/s?

Accepted Answer

The answer of What is the magnitude of the momentum...

Question 18

Two ice skaters, one with a mass of 45 kg and the other with a mass of 60 kg, push off against one another starting from a stationary position. After they have pushed off, the relative speed at which they separate is 0.600 m/s. What is the speed of the 60-kg skater?

Accepted Answer

A)  0.343 m/s 
B)  0.257 m/s 
C)  0.375 m/s 
D)  0.750 m/s 
E)  0.225 m/s

Question 19

An air track cart with mass m and speed v moving along an air track collides with a stationary cart with a mass m/3. After the collision the first cart has a speed v/2. What is the speed of the second cart?

Accepted Answer

The answer of An air track cart with mass m...

Question 20

State Newton's second law in terms of momentum.

Accepted Answer

The answer of State Newton's second law in terms of...

Exam 9: Linear Momentum and Collisions