Question

From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m s–1. Calculate the initial recoil velocity of the rifle.​

Answer 1

Answer:

Given, the Bullet’s mass (m1) = 50 g

The rifle’s mass (m2) = 4kg = 4000g

Initial velocity of the fired bullet (v1) = 35 m/s

Let the recoil velocity be v2.

Since the rifle was initially at rest, the initial momentum of the rifle = 0

Total momentum of the rifle and bullet after firing = m1v1 + m2v2

As per the law of conservation of momentum, the total momentum of the rifle and the bullet after firing = 0 (same as initial momentum)

Therefore, m1v1 + m2v2 = 0

Therefore, the recoil velocity of the rifle is 0.4375 meters per second in the direction opposite to the trajectory of the bullet (backward direction).