Question

A bullet of mass 100g is fired from a gun of mass 20kg witha velocity of 100m/s calculate the velocity of recoil of the gun

Answer 1

We know

Momentum = mass X velocity

Thus, we can say:

Momentum before gun is fired = momentum of gun after firing + momentum of bullet after firing

If we consider recoil velocity of gun as V m/s. and units will be 100g = 0.1 kg

By conservation of momentum:

 (20kg + 0.1 kg) X 0 m/s = (20 kg X V m/s) + (0.1 kg X 100 m/s)

 =>0 = 20V + 10

 =>V = -0.5m/s

Answer 2

Answer:

We know

Momentum = mass X velocity

Thus, we can say:

Momentum before gun is fired = momentum of gun after firing + momentum of bullet after firing

If we consider recoil velocity of gun as V m/s. and units will be 100g = 0.1 kg

By conservation of momentum:

 (20kg + 0.1 kg) X 0 m/s = (20 kg X V m/s) + (0.1 kg X 100 m/s)

 =>0 = 20V + 10

 =>V = -0.5m/s

Hope it will help you