Question

What is the work done on the earth by the gravitational force of the sun during the earth’s motion around the sun?

Answer 1

The work done by the Sun’s gravitational force on the Earth is zero, assuming Earth moves in a circular orbit.

At every instant, the gravitational force acts radially towards the Sun, whereas the Earth’s displacement is tangential to its orbit. Thus, the two are perpendicular.

W = F s cos 90° = 0

Therefore, the gravitational force of the Sun does zero work on the Earth during its circular motion.