Question

From a rifle of mass `4kg`, a bullet of mass `50kg` is fired with an initial velocity of `35m//s`. Calculate the initial recoil velocity of the rifle.

Answer 1

Here, mass of bullet, `m_(1)= 50g =50/(1000)kg= 1/20kg`, mass of rifle, `m_(2)= 4kg`
velocity of bullet, `v_(1)=35m//s`, recoil velocity of rifle, `v_(2)=?`
Applying the principle of conservation of linear momentum, we get
`m_(1)v_(1)+m_(2)v_(2)=0` or `v_(2) = -(m_(1)v+_(1))/m_(2)= -1/20xx35/4= -7/16 m//s`
Negative sign indicates that rifle moves in a direction opposite to the direction of bullet.