Chapter 14, Problem 10A

Why does the force of gravity do no work on a satellite in circular orbit, but does do work on a satellite in an elliptical orbit?

To determine

The reason for the work done by gravitational force on a satellite in an elliptical orbit but not in circular orbit.

Explanation of Solution

Introduction:

A force does some work on an object when the force has component acting towards the motion of the object. Work done on object is zero when the force acts perpendicular to the direction of motion of the object.

When the satellite moves in an elliptical orbit, there is a component of gravitational force which acts towards the motion of the satellite and hence gravitational force does some work on the satellite.