Mass of the rifle, m1 = 4 kg
Mass of the bullet, m2 = 50g = 0.05 kg
Recoil velocity of the rifle = v1
Bullet is fired with an initial velocity, v2 = 35 m/s
Initially, the rifle is at rest.
Thus, its initial velocity, v = 0
Total initial momentum of the rifle and bullet system = (m1 + m2)v = 0
Total momentum of the rifle and bullet system after firing:
= m1v1 + m2v2 = 4(v1) + 0.05×35 = 4v1 + 1.75
