Assertion (A) : A rocket works on the principle of conservation of linear momentum

Reason (R) : Whenever there is the change in momentum of one body, the same change occurs in the momentum of the second body of the same system but in the opposite direction.

Explanation:

A rocket works on the principle of the conservation of linear momentum, which states that the total momentum of a system remains constant if no external force acts on it. As the rocket expels gas with high velocity in one direction, the rocket itself gains momentum in the opposite direction, propelling it forward.

The Reason (R) correctly explains this principle: when the expelled gas (one part of the system) experiences a change in momentum in one direction, the rocket (the second part of the system) experiences an equal and opposite change in momentum, maintaining the conservation of linear momentum.

Final Answer

Both A and R are correct, and R is the correct explanation of A.