Gravitational potential

Gravitational potential energy is usually calculated using the formula ∆Ep=mg∆h.this can also be thought of as the work done moving the mass. The force being pushed against is given by mg and the distance moved is ∆h. This only works when the field is uniform like on the earth's surface.

The gravitational potential, V, at a point is the work done per unit mass to move a small object from infinity to that point.

The potential:  V=W/m
The work done to move a mass is:  ∆W=m∆V

Imagine you are in a space rocket, about to blast off from the surface of a planet. The planet's gravitational field extends far into space although it becomes weaker with increased distance from the distance from the planet. To escape from the planet's pull due to gravity, the rocket must do work against the force of gravity on it due to the planet. If the rocket fuel doesn't give enough energy to escape, the rocket will return.