This is part of the HSC Physics Syllabus Module 5: Advanced Mechanics.

There are many applications of gravitational force & energy in outer space. In this post, we will derive quantitatively and apply the concepts of gravitational force and gravitational potential energy in radial gravitational fields to a variety of situations including:

- Change of energy between orbits

Gravitational potential energy is the energy an object possesses because of its position in a gravitational field.

The formulae for gravitational potential energy is:

GPE = -G \frac{Mm}{r}

### Change in energy between orbits

The change in energy between orbits is the change in gravitational potential energy or work! Remember to always to final energy minus initial energy to find the change in work.