Question

A revolver of mass 5kg releases a bullet of mass 0.10kg at a speed of 100m/s.find the revolvers speed recoil

Answer 1

Mass of revolver $M=5kg$

Mass of bullet $m=0.10kg$

Velocity of bullet $v=100m/s$

Velocity of revolver $V-?$

Solution:

$v_0=0\;m/s$ velocity of revolver and bullet (before)

Momentum of the system (before) $p_0=(M+m)v_0=0$

Momentum of the system (after) $p=MV+mv$

$p_0=p$

$0=MV+mv$

$0=5V+0.10*100$

$V=-2\; m/s$

The negative sign indicates the revolver recoil backwards.