Question

A 35.4 g bullet strikes a 18.0 kg stationary wooden block and embeds itself in the block. The block and the bullet fly off together at 13.3 m/s.



What was the initial velocity of the bullet?

Answer 1

mass of the bullet $m=35.4$ g

mass of the wooden block $M=18$ kg

velocity of block and bullet afterwards $v=13.3$ m/s

We need to find initial velocity of bullet $v_0$

Let's write conservation law of momentum:

$mv_0=(m+M)v$

Then $v_0=v{\frac {m+M} {m}}=6776$ m/s