Question

A 3 g bullet has a muzzle velocity of 290 m/s when fired by a rifle with a weight of 4 N
Determine the recoil speed (in m/s) of the rifle

Answer 1

To determine the recoil speed of the rifle, we can use the principle of conservation of momentum.

The momentum of the bullet can be calculated as:
Momentum of bullet = mass of bullet * velocity of bullet
= 3g * 290 m/s
= 0.003 kg * 290 m/s
= 0.87 kg*m/s

According to the law of conservation of momentum, the momentum of the bullet must be equal and opposite to the momentum of the rifle:
Momentum of rifle = -momentum of bullet

Let the recoil speed of the rifle be v m/s. The mass of the rifle is 4 kg. So, the momentum of the rifle can be calculated as:
Momentum of rifle = mass of rifle * recoil speed of rifle
= 4 kg * v
= 4v kg*m/s

Now, according to the conservation of momentum,
4v = -0.87
v = -0.87/4
v = -0.2175 m/s

Therefore, the recoil speed of the rifle is 0.2175 m/s in the direction opposite to the bullet's momentum.