## College Physics (4th Edition)

The expression for gravitational potential energy is: $U_g = -\frac{GMm}{r}$ At perihelion, the magnitude of the gravitational potential energy is at its maximum value since $r$ is at a minimum. However, since $U_g \lt 0$, the gravitational potential energy is at its most negative value, that is its minimum value, at perihelion. The correct answer is: (b) its minimum value