• # question_answer A ball of mass m moving with velocity V makes a head-on elastic collision with a ball of the same mass moving with velocity 2V towards it. Taking direction of V, the positive velocities of the two balls after collision are A) $-V$and 2V B) 2V and $-V$ C) V and $-2V$ D) $-2V$and V

[d] Initial velocities of balls are $+V$and$-2V$, respectively, and we know that for given condition velocities get interchanged after collision .So the velocities of two balls after collision are $-2V$and V, respectively.