Which physical quantity allows a satellite to stay in its orbit without the need for continuous propulsion?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. Orbital velocity.
The primary physical quantity that allows a satellite to stay in its orbit without the need for continuous propulsion is its orbital velocity (or speed).
Orbital velocity is the precise horizontal speed the satellite needs to achieve a balance: it moves so fast that as it falls toward Earth due to gravitational pull, the curvature of its path matches the curvature of the Earth.
The gravitational pull provides the necessary centripetal force to keep the satellite in a curved path.
Since the satellite is moving at the correct orbital velocity and is outside the significant effect of atmospheric drag (in low-Earth orbit, continuous propulsion is often needed to counter drag), it continuously "falls around" the Earth in a stable, elliptical, or circular orbit without expending fuel.