Suppose a planet is travelling in an elliptical orbit around the sun. The work done on the planet by the sun's gravitational force

Step-by-step solution

The gravitational force exerted by the sun on a planet is a central and conservative force. For any conservative force, the work done over a closed path is zero. Since one full revolution corresponds to a closed path, the total work done on the planet during one complete revolution is zero. Thus, option (1) is correct. The work done by the gravitational force over a small displacement d r is given by dW = F d r . In an elliptical orbit, the angle between the gravitational force and the velocity vector is generally