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 explanation for the correct option

Option (a): Momentum

Conservation of Momentum

1. Momentum is defined as the product of mass and velocity through which an object is moving.
2. Conservation of momentum states that for an isolated system the momentum remains conserved.
3. Sum of initial momentum = Sum of final momentum.

Working of rocket

1. The hot gases are expelled by the engine of a rocket or jet.
2. The gases exert a downward force on the air and the air in return exert a reactive upward force on the engine.
3. This is governed by newton's third law of motion. According to newton's 3rd law, if an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A.
4. Just like a balloon moves upward when air is released from its opening.
5. For two bodies acting upon each other, the momentum remains conserved.
6. Momentum of the rocket = Momentum of the gases expelled from the rocket.

Hence, a rocket works on the principle of conservation of momentum.

The explanation for the incorrect option

Option A: Mass

The law of conservation of mass states that mass within a closed system remains the same over time.

Option B: Energy

Energy can neither be created nor be destroyed but can change from one form to another.

Thus, option (c) is correct.