Question

A 30 gram Bullet leaves a rifle with a velocity of 300 metre/second and the Rifle recoils with a velocity of 0.60 metre/second ,find the mass of the rifle.

Answer 1

this is a straight forward conservation of momentum problem. Mass of the bullet times its velocity equals mass of the firearm times its velocity. So, taking the mass of the bullet (in kg.) as .015 x 300 = .6 x Mass gun, gives 7.5 kg. as the mass of the gun.