Answer to Question #75065 in Classical Mechanics for Don

Question

a moving ball hits a stationary one (elastic). Why does the first ball stop and the other move. ie why dont they move off together? I saw an answer saying that conservation of motion requires a continuation in the same direction. Yes but that doesnt explain why they dont share both energy and momentum. Eg throw a medicine ball at a clown on ice, they move off together. The ball doent stop and the clown move? A ball hits another ball and one stops the other moves.

Answer 1

They will move off together if the collision is inelastic. In this case the mechanical energy is not conserved.
So, in your scenario two balls cannot move off together.