Question

A fast moving bullet of mass $m$ , velocity $v$, collides with wooden block of mass $M$ moving with $V$. Calculate the speed of bullet to stop the wooden block. (assuming that the bullet became embedded inside)

• A. $\frac{mV}{m+M}$
• B. $\frac{MV}{m+M}$
• C. $\frac{mV}{M}$
• D. $\frac{MV}{m}$
• E. $\frac{(m+M)V}{m}$

Answer 1

The correct option is D $\frac{MV}{m}$

Since the block and bullet system stops after the collision, the final momentum of the system must be zero.

No external force acts on the system in horizontal direction.

Thus the momentum before and after collision remains same of the bullet-block system.

Thus $mv-MV=0$

$⟹v=\frac{MV}{m}$