Question

A gun of mass 3kg fires a bullet of mass 30g. The bullet takes 0.003s to move through the barrel of the gun and acquires a velocity of 100 m/s. Calculate: 

a) the velocity with which the gun recoils 

b) the force exerted on gunman due to recoil of the gun

Answer 1

Mass of the gun, m₁ = 3kg 

Mass of bullet, m₂ = 30g = 0.03kg 

Velocity of bullet, v₂ = 100 m/s 

a) According to conservation of momentum 

m₁v₁ = m₂v₂ v₁ = 1 m/s 

b) Initial velocity of the gun, u = 0 m/s 

Final velocity of the gun, v = 1 m/s 

Time, t = 0.003s 

Acceleration, a = (u-v)/t= 1000/3 m/s² 

Force = ma = 1000N