Question

Suppose a spacecraft is moving in a region of space where the gravitational force acting upon it is negligible. Suggest how can it change its velocity.

Answer 1

A spacecraft can alter its velocity by using its engine to release gases in a specific direction, demonstrating Newton’s Third Law of Motion.

When the engine ejects gas in one direction, the gas exerts an equal and opposite force on the spacecraft. This reaction force causes acceleration, leading to a change in the spacecraft’s velocity. For instance, to speed up, the spacecraft releases gas backwards, opposite to its direction of motion. To slow down, it releases gas in the same direction as its motion.