An Earth satellite is in a circular orbit at an altitude of 500 km.

Explain why the work done by the gravitational force acting on the satellite is zero.

Using the work-energy theorem, what can you say about the speed of the satellite?

Speed Unchanged.

Explanation:

As work is defined as a product of force over a distance. If the distance in altitude is constant = 500km, there's 0 change in distance and force, no work would be done by the gravitational force.

Since potential energy of the satellite is unchanged, unless there's additional internal energy source, the kinetic energy would remain unchanged, so would its speed.