Question

Name the quantity that remains conserved in rocket propulsion

Answer 1

In rocket propulsion we can use two laws to explain it.

1. Newton's third law of motion

For every action there is an equal and opposite reaction.

When the reactants of the chemical are ejected from the rocket at a force, there is an equal and opposite force that will act on the rocket and cause it to move forward.

2. Law of conservation of momentum

When the rocket is at the ground, it is still at rest and thus the velocity is zero. Since momentum is equal to mass multiplied by velocity, the momentum will be zero.

By law of conservation of momentum this momentum will be equal to the momentum the rocket gains at higher velocity. This implies that at any point the rocket should be at zero momentum.

Answer : The quantity conserved is thus momentum.