question_answer

A ball of mass m moving with vel. v strikes head on elastically with a number of balls of same mass at rest in a line. Only one ball from other side moves with same velocity. Explain why not two balls move simultaneously, each with vel. v/2?

Answer:

                When one ball of mass m moves with vel. v, both linear momentum and K.E. are conserved. If two balls were to move simultaneously, each with vel. v/2; linear momentum will be conserved, but K.E. will not be conserved.