Dynamics, Circular Motion, Momentum

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)

Captain America's shield hits some useless villian in the face and it bounces back. Who experiences the greater impulse, his shield or the useless villian?

• Both are the same
• Shield
• Uesless VIllian
• Cannot be determined

A baseball player catches a ball by moving his hand back in the direction of the ball's motion. Doing this results in a lower force acting on the player's hand. Why?

• Increased time of impact
• Decreased time of impact
• Impact velocity is lessend
• the change in momentum is decreased

• ΔP_A = ΔP_D > ΔP_B = ΔP_C

• ΔP_A > ΔP_C = ΔP_B > ΔP_D

• ΔP_A > ΔP_B > ΔP_C > ΔP_D

• ΔP_A = ΔP_D > ΔP_B > ΔP_C

What are the two factors that affect the momentum of an object?

• speed and velocity

• time and mass

• distance and displacement

• mass and velocity

What would happen to the momentum of a toy car if the mass is doubled and the velocity decreases by 1/2?

• It decreases by 1/4

• It decreases by 1/2

• Stays the same

• It is doubled

Momentum is conserved in this type of collision

• elastic
• inelastic
• momentum is conserved in both types of collisions

A Russian cosmonaut(87 kg) and USA astronaut(94 kg) are outside the ISS and decide to run a momentum experiment. They are motionless facing each other palm to palm, then push apart from each other. What happens to their momentum?

• their total momentum doubles

• their total momentum decreases

• the guy with the smaller mass has less momentum

• their momenta are opposite but equal

A car of mass m, traveling at speed v, stops in time t when maximum braking force is applied. Assuming the braking force is independent of mass, what time would be required to stop a car of mass 2m traveling at speed v?

• ½t
• t
• √2 t
• 2t

Two objects, P and Q, have the same momentum. Q can have more kinetic energy than P if it has:

• More mass than P 
• The same mass as P 
• More speed than P 
• The same speed as P