Question

Two objects have masses of `36 MG` and `18 MG`. How much does the gravitational potential energy between the objects change if the distance between them changes from `81 m` to `3 m`?

Answer 1

The distance reduces by a factor of `27` so the energy rises by a factor of 27

Explanation:

The gravitational energy is proportional to both the product of the masses and inversely proportional to the distance between them. Only the separation changes here and, as you are asked for a relative answer, the fact that the masses do not alter means they are not relevant.

The equation is `E_g = G. (m_1.m_2)/r` where G is the universal gravitational constant.