Question

From a rifle of 4kg a bullet of mass 0.01kg is fired with a velocity of 35 m/s calculate the recoil velocity of a rifle ? F

Answer 1

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= 35m/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= 0.05 — 35= 4v1 + 1.75

According to the law of conservation of momentum:

Total momentum after the firing = Total momentum before the firing 4v1 + 1.75= 0

v1= -1.75 / 4= -0.4375 m/s

The negative sign indicates that the rifle recoils backwards with a velocity of 0.4375 m/s.