Physics 9702/43 — May/June 2014

Define gravitational potential at a point.

A stone of mass $m$ has gravitational potential energy $E_P$ at a point X in a gravitational field. The magnitude of the gravitational potential at X is $\phi$.

State the relation between $m$, $E_P$ and $\phi$.

An isolated spherical planet of radius $R$ may be assumed to have all its mass concentrated at its centre. The gravitational potential at the surface of the planet is $-6.30 \times 10^7\ \text{J kg}^{-1}$.

A stone of mass $1.30\ \text{kg}$ is travelling towards the planet such that its distance from the centre of the planet changes from $6R$ to $5R$.

Calculate the change in gravitational potential energy of the stone.

change in energy = ______ $\text{J}$