In: Physics
6.) A 'Newton's Cradle' consists of 7 identical metal balls which are free to swing back and forth. When two are pulled back and then released, they stop after colliding elastically with the other 5 balls. The two balls on the other end then swing upwards with the same speed as the first two balls. Using the conservation of momentum and mechanical energy, explain why only two balls move afterwards. Use words and/or equations to explain your answer.