A bullet of mass `50 kg` is fired with a speed of `200 m//s` from a gun of mass `2 kg` . Find the recoil velocity of the gun.

Explanation

Since for ( gun + bullet) the system , the external force is zero. Hence by momentum conservation
Initial momentum = Final momentum
`0 = mu + Mv`
Mass of bullet , `m = 50 g = 50 xx 10^(-3) kg , u = 200 m//s`
Mass of gun , `M = 2kg`
`0 = 50 xx 10^(-3) xx 200 + 2v`
`v = -5m//s`
where the `-ve` sign indicates that the velocity of gun is opposite to that of the bullet.