Question

The mass of bullet is 100 g. It is fired from a gun of mass 20 kg with a velocity of 100 m/s. Determine the recoil speed of the gun

Answer 1

Let us assume the recoil velocity of the guns as V

 

Before firing,

The system (gun+bullet) is at rest, therefore, initial momentum of the system =0

Final momentum of the system = momentum of bullet + momentum of gun

mv+MV = 1/10 X 100 + 20 V= 10 +20 V

 

On applying law of conservation of momentum,

Final momentum = Initial momentum

10+20V=0

20V=−10

V=− 10/20 = -0.5ms-¹

 

Negative sign indicates that the direction of recoil velocity of the gun is opposite to the direction of the velocity of the bullet.

 

 

Recoil speed of the gun = -0.5m/s