Question

Give two illustrations to support law of conservation of momentum

Answer 1

• Consider the example of air-filled balloon as described under the third law of motion.In this case, balloon and the air inside it form a system.Before releasing the balloon,the system was at rest and hence the initial momentum of the system was zero.As soon as the balloon is set free,air escapes out of it possesses momentum.To conserve momentum, the balloon moves in a direction opposite to that of air rushing out.

• A system of gun and a bullet.Before firing the gun, both the gun and the bullet are at rest,so the total momentum of the system is zero.As the gun is fired, bullet shoots out of the gun and acquires momentum.To conserve momentum of the system,the gun recoils.According to the law of conservation of momentum,the total momentum of the gun and the bullet will be zero after the gun is fired.Let m be the mass of the bullet and v be the velocity on firing the gun; M be the mass of the gun and V be the velocity with which it recoils.

• Rockets and jet engines also work on the law of conservation of momentum.In these hot gases produced by burning of fuel rush out with a large momentum, Due to this, these machines gain an equal and opposite momentum.This momentum enables the rockets and jet engines with very high velocities.