Momentum

A truck moves along a friction-less level road at a constant speed. The truck is open on top. A large load of gravel is suddenly dumped into the truck. What happens to the velocity of the truck?

• It increases.

• It remains the same.

• It decreases.

• More information is required

• It stops immediately.

A car of mass m is moving with a momentum p. How would you represent its kinetic energy in terms of these two quantities?

• mp

• 0

When a ping-pong ball rolling with a speed of 3.0 m/s collides with a bowling ball at rest, the ping-pong ball’s speed after the collision will be approximately:

• 0

• 3.0 m/s

• 6.0 m/s

• 12.0 m/s

• 9.0 m/s

A bowling ball moving with speed v collides head-on with a stationary tennis ball. The collision is elastic, and there is no friction. The bowling ball barely slows down. What is the speed of the tennis ball after the collision?

• Nearly v.

• Nearly 2v.

• Nearly 3v.

• Nearly 4v.

• 0

An object with a mass of 2 kg is accelerated from rest. The graph shows the magnitude of the net force as a function of time. At t = 4 s, the object’s velocity would have been closest to which of the following?

• 2 m/s

• 4 m/s

• 10 m/s

• 13 m/s

• It cannot be determined.

Two blocks are on a frictionless surface and have the same mass m. Block 2 is initially at rest. Block 1 moves to the left with speed 4v and collides inelastically with block 2.

What is the final speed of the system of two blocks?

• V

• 2V

• 3V

• 4V

• 5V

Two blocks are on a frictionless surface and have the same mass m. Block 2 is initially at rest. Block 1 moves to the left with speed 4v and collides inelastically with block 2.

What is the final speed of block 1 if they collide elastically?

• 0

• v

• 2V

• 3V

• 4V

Two blocks are on a frictionless surface and have the same mass m. Block 2 is initially at rest. Block 1 moves to the left with speed 4v and collides inelastically with block 2.

What is the final speed of block 2 if they collide elastically?

• v

• 2V

• 3V

• 4V

• 7V

A toy truck moves freely along a track at 2 m/s and collides with a toy Subaru that is at rest. After the collision, the two vehicles stick together and move continuously. What is the magnitude of the velocity of both vehicles after the collision if the toy truck weighs 3 kg and the toy Subaru weighs 1 kg?

• 1.5 m/s

• 2 m/s

• 3m/s

• 5 m/s

• 6 m/s

A carpenter is initially at rest on an icy pond throws a hammer. After being thrown, the hammer moves in one direction while the carpenter moves off in the other direction. Which of the following correctly describes this occurrence?

• The carpenter and the hammer will have equal amounts of kinetic energy.

• The hammer will have the greater magnitude of momentum.

• The carpenter will have the greater magnitude of momentum.

• The hammer will have greater kinetic energy.

• The carpenter and the hammer will have equal and opposite amounts of momentum.