Question

A bullet of mass 10g is fired at a speed of 400m/s from a gun of mass 4kg.what is the recoil velocity of a gun?

Answer 1

Hi,

Solution)

Given-
Mass of the gun(m ᵃ) =  4 kg 
Mass of the bullet(m ᵇ)   =  10 g

Velocity of gun (v ᵃ) = x
Velocity of bullet (v ᵇ) = 400 m/s

Recoil Velocity
m ᵃ * v ᵃ = m ᵇ * v ᵇ

Substituting Values in above equation

4 * x = 0.01 * 400
4 * x = 4
x = 4/4
x = 1

Answer) The recoil velocity is 1 m/s because here no external force is acted hence momentum of gun+bullet is conserved 
initial momentum = finial momentum.

THANK YOU

Answer 2

Given-

Mass of the gun(m ᵃ) =  4 kg 

Mass of the bullet(m ᵇ)   =  10 g

Velocity of gun (v ᵃ) = x

Velocity of bullet (v ᵇ) = 400 m/s

Recoil Velocity

m ᵃ * v ᵃ = m ᵇ * v ᵇ

Substituting Values in above equation

4 * x = 0.01 * 400

4 * x = 4

x = 4/4

x = 1

Answer) The recoil velocity is 1 m/s because here no external force is acted hence momentum of gun+bullet is conserved 

initial momentum = finial momentum.