Does gravity do a positive work?

Question

The moon revolves around the earth in a circular orbit kept there by gravitational force exerted by the earth.

Answer 1

Hi. The Moon's orbit is elliptical. The Earth and Moon orbit around a common center, not the center of the Earth. Your answer is that the masses are balanced about this point. So, in this case, no.

Answer 2

Definition of work = Force x distance moved x cos(angle between them).

Since force and distance are at 90 degrees, work done =0, otherwise we're in big trouble if moon slows down or speeds up and hits us or flies away!

Answer 3

gravity only doe work if there is a change in height..... if your question is does the gravity of the earth do work on the moon the answer is no because the moon is not changing height WRT the earth.