A 3 kg block rests on a rough horizontal table. A rope is attached to the block and is pulled with a force of 11N to the
left. As a result, the block accelerates at 3 m/s2. The coefficient
of kinetic friction Hk between the block and the table is

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.