Answer to Question #157446 in Mechanics | Relativity for Sage Topaz

Question

The sun exerts a force of 4 X 10²⁸ N on Earth, and the Earth travels 9.4 x 10¹¹m in its annual orbit around the sun. How much work does the sun does on Earth in the course of one the year?

Answer 1

Gravitational force is the conservative force. Thus, its net work done by the force when moving an object through a trajectory that starts and ends in the same place is zero (see point 2 in https://en.wikipedia.org/wiki/Conservative_force#Mathematical_description). Since the positions of the Earth at the start and at the end of the same year match, the net work the Sun does on Earth is equal to 0.

Answer. 0.