Momentum Review

Momentum Review

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Momentum

• it's a vector

• p = mv

Multiple Choice

Parkour Peter bends his knees upon landing in order to ____

• reduce his change in momentum

• increase his change in momentum

• increase his landing time

• increasing his landing force

Impulse

Multiple Choice

A car of mass 200kg starts from rest and is pushed to the left for 10 seconds to get to the final velocity of 25 m/s, what is the force acting on the car?

• -500 N

• -300 N

• -5000 N

• -80 N

Force versus Time graph

Multiple Choice

A student obtains data on the magnitude of force applied to an object as a function of time and displays the data on the graph above.

Answer the following question for the information and diagram above.

The increase in the momentum of the object between t = 0 s and t = 4 s is most nearly

• 40 Ns

• 50 Ns

• 60 Ns

• 80 Ns

• 100 Ns

Multiple Choice

Both students experience the same magnitude of ____

• force of impact

• time of impact

• change in momentum

• all of the above

Conservation of Momentum

Multiple Choice

When a bug hits your car, what goes under the greatest change in momentum.

• Both the same
• The bug
• The car
• You in the car

Multiple Choice

A person on a stationary skateboard throws a bowling ball with a velocity of 5.0 m/s. What is a possible speed of the person after the throw?

(Make reasonable assumptions about the mass of humans and bowling balls)

• 0 m/s

• 1.5 m/s

• 5.0 m/s

• 7.5 m/s

Fill in the Blank

A girl on frictionless roller skates catches a medicine ball thrown at her. With what velocity do the girl and ball move after the catch? No units

Multiple Choice

A train-car of mass M moves at a velocity v at another stationary train-car with mass m. They collide and stick together. What is the new velocity of the system?

• MV/(M + m)

• MV/2

• MV/(M - m)

• (M + m)V/(M - m)

Multiple Choice

Two blocks are on a horizontal, frictionless surface. Block A is moving with an initial velocity of v₀ toward block B, which is stationary, as shown above. The two blocks collide, stick together, and move off with a velocity of v₀/3 . Which block, if either, has the greater mass?

• Block A

• Block B

• Neither; their masses are the same.

• The answer cannot be determined without knowing the mass of one of the blocks.

Multiple Choice

Two identical blocks with mass 5.0 kg each are connected to the opposite ends of a compressed spring. The blocks initially slide together on a frictionless surface with velocity 2 m/s to the right. The spring is then released by remote control. At some later instant, the left block is moving at 1 m/s to the left, and the other block is moving to the right. What is the speed of the the other block

• 0 m/s

• 2 m/s

• 4 m/s

• 5 m/s

Multiple Choice

Two identical blocks with mass 5.0 kg each are connected to the opposite ends of a compressed spring. The blocks initially slide together on a frictionless surface with velocity 2 m/s to the right. The spring is then released by remote control. At some later instant, the left block is moving at 1 m/s to the left, and the other block is moving to the right. What is the speed of the the center of mass of the system

• 0 m/s

• 2 m/s

• 3 m/s

• 4 m/s

Multiple Choice

A railroad car of mass m is moving with speed v when it collides with and connects to a second railroad car of mass 3m, initially at rest, as shown above. How do the speed and kinetic energy of the connected cars compare to those of the single car of mass m before the collision?

• speed is less. kinetic energy is less

• speed is less. kinetic energy is the same

• speed is the same. kinetic energy is less

• speed is the same. kinetic energy is the same

• speed is greater. kinetic energy is the same

Multiple Choice

Which of the following is true of the conservation of momentum and kinetic energy?

• Momentum is conserved only in elastic collisions.

• Momentum is conserved only in inelastic collisions.

• Kinetic energy is conserved only in elastic collisions.

• Kinetic energy is conserved only in inelastic collisions.

• Both require the same conditions in order to be conserved.