A moving train car collides with another train car that is motionless on the track. The train cars are the same
size. How does the final momentum of the two cars compare to the momentum of the first car?

a. Momentum is doubled. b. It is zero.

b. It is zero

c. They are both added together Md. It is half the beginning value.

d. It is half the beginning value.

Consider a small frictionless puck perched at the top of a fixed sphere of radius r. if the puck is given a tiny nudge so that it begins to slide down, through what vertical height will it descend before it leaves the surface of the sphere? [hint: use conservation of energy to find the puck's speed as a func e conservation of energy to find the puck's speed as a function of its height at what value of this normal force does the puck leave the sphere? ] here on the puck.