## College Physics (4th Edition)

$U = -1.125\times 10^{-5}~J$
We can find the electric potential energy: $U = \frac{k~q_1~q_2}{r}$ $U = \frac{(9.0\times 10^9~N~m^2/C^2)(10.0\times 10^{-9}~C)(-10.0\times 10^{-9}~C)}{0.080~m}$ $U = -1.125\times 10^{-5}~J$