Question

Q109. an astronaut weighing 100 kg fires a bullet weighing 1 kg with a gun of 10 kg at the speed of 50 metres/second. what will be the recoil velocity of the gun?



(a) 5 cm/s



(b) 50 cm/s



(c) 0.5 cm/s



(d) 0.05 cm/s

Answer 1

it should be the d option

Answer 2

Momentum equals to :

Mass × Velocity

We substitute into the formulae and get :

0.03 × 330 = 10 × V

9.9 = 10V

V = 0.99 m/s

Momentum before firing is zero since both the gun and the bullet are at rest and their velocities are zero.

Momentum after firing is equal to momentum of the gun plus the momentum of the bullet which are equal and opposite.

This is therefore :

330 × 0.03 × 2 = 19.8Kgm/s