Question

Rocket works on the principle of conservation of _______.

• A. Mass
• B. Energy
• C. Momentum
• D. Velocity

Answer 1

The correct option is C Momentum

The rocket operates on the principle of conservation of momentum. As a rocket moves upwards when the gases are ejected in the opposite direction downward. The rockets gain momentum equal to the momentum of the gas expelled from the engine, but in the opposite direction.

That is before firing, the momentum is zero and on firing the momentum of escaping gases are in the opposite direction.
Momentum of rocket $+$ Momentum of escaping gases$=0$
Momentum of rocket$=-$ Momentum of escaping gases.