Three English majors observed a satellite orbiting above the earth\'s surface. T

Question

Three English majors observed a satellite orbiting above the earth's surface. They are discussing the work done on the satellite by the gravitational force and what the work-kinetic energy theorem says about the satellite's speed.
With which, if any, do you agree?


April: "Gravity has to provide a centripetal force for the satellite to stay in circular orbit. That force times the distance the satellite moves equals the work done, and that work equals the change in kinetic energy as the satellite accelerates."
Benjamin: "I agree that gravity provides a centripetal force. But that force is perpendicular to the velocity of the satellite, not in the direction of movement. There is no work done by gravity and there are no other forces, so the work-kinetic energy theorem says there is no change in KE. Therefore, the speed of the satellite cannot change."
Celine: "You're both missing the point. A great deal of work was done against gravity putting the satellite into orbit, and that work provided the change in KE that keeps the satellite moving. There must be continuous work against gravity for the satellite to stay up, and that provides the KE to keep the satellite moving."
None of them are correct. Back to Physics for them all!

Explanation / Answer

I agree with Benjamin, the satellite is moving perpendicular to the force of gravity that is keeping it in orbit. So the velocity of the satellite is not changing since no net work is being done on it

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