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 wy not two balls move simultaneously, each with ve. `v//2` ?

Explanation

When one ball of mass m moves with ve. 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.