Question

Recoil of gun is based on the principle of conservation of momentum.

1. State the principle of conservation of momentum.

2. Explain the reoil velocity of gun.

3. A bullet of mas 100g is fired from a rife of mass 200 kg with a speed of 50 m/s. Calculate the recoil velocity of the rife.

Answer 1

1. According to law of conservation of linear momentum, if the external force acting on a body is zero, total linear momentum remains constant. According to Newton’s second law.

F = \(\frac{dp}{dt}\)

If F = 0, \(\frac{dp}{dt}\) = 0 i.e; P is constant.

2. Let M, m be the mass of gun and bullet respectively. Let V and ν be the velocities of gun and bullet after firing.

According to consevation of momentum

Total momentum before firing = Total momentum after firing

∴ O = MV + m ν

-MV = mν

The above equation shows that when bullet moves in forward direction, the gun moves in back direction. This motion of gun is called recoil of gun.

3. M = 200kg, m = 100g = 0.1kg

ν = 50 m/s, V = ?

MV = mν

200 × V = 0.1 × 50

V = \(\frac{0.1×50}{200}\) m/s.