# Gravitational Potential

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Gravitational potential, $\phi$, at a point in a gravitational field is the work done per unit mass, by an external force, in bringing the mass from infinity to that point.

$\phi = \, – G \frac{M}{r}$

Units for $\phi$ is $J \, Kg^{-1}$.

At infinity, $\phi$ is assumed to be zero.