Ablock of mass 15 kg starts from rest and slides down a 20° angle inclined plane. the coefficient of kinetic friction is 0.3. after sliding a distance of 34cm, it contacts a spring of force constant 350 n/m. how far does the block compress the spring?

Arailroad car collides with and sticks to an identical railroad car that is initially at rest. after the collision, the total kinetic energy of the two cars is a) the same as before. b) half as much as before. c) one third as much as before. d) one fourth as much as before. e) twice as much as before.