Question

A body of mass $M$ moves with velocity $v$ and collides elastically with another body of mass $m(M>>m)$ at rest then the velocity of body of mass $m$ is

• A. $v$
• B. $2v$
• C. $v/2$
• D. Zero

Answer 1

The correct option is B $2v$

Since collision is elastic $⟹e=1$

let's say velocity of body be $v^{\prime }$, and since $M>>m$, then velocity of $M$ won't change.

$e=\frac{v^{\prime }-V}{V}$

$1=\frac{v^{\prime }-V}{V}$

$v^{\prime }=2V$

When target is very light and at rest then after head on elastic collision it moves with double speed of projectile i.e. the velocity of body of mass m will be $2v$