# Average potential and kinetic energies for H ground state

## Homework Statement

Calculate the average potential and kinetic energies for the electron in the ground state of hydrogen.

## The Attempt at a Solution

I know that KE = E - <U(r)>. I know that E = (-KZ^2e^2)/(2a0) and I know that U(r) = -KZe^2/r but I cant figure out how to get the average potential energy from this so that the denominator is the same as the E and so that they can add together to get KE.

$$<KE> = \langle \psi \mid \frac{p^2}{2m}\mid \psi \rangle$$
$$<U> = \langle \psi \mid \frac{ke^2}{r}\mid \psi \rangle$$