Gravitational Potential Energy (Also seen in AS Unit 2)

In Unit 2 we calculated the gravitational potential energy of an object of mass m at a height of h with:

This is only true when the gravitational field strength does not change (or is constant) such as in a uniform field.

For radial fields the gravitational field strength is given by

We can use this to help us calculate the gravitational potential energy in a radial field at a height r.

(We have dropped the negative sign because energy is a scalar quantity)

If we look at the top equation for gravitational potential we can see that the gravitational potential energy can be calculated using:

The work done to move an object from potential V₁ to potential V₂ is given by:

which can be written as

Gravitational Potential Energy is measured in Joules, J