13.4.1—Gravitational potential at a point as the work done per unit mass in

Gravitational potential at a point is the work done per unit mass by an external agent bringing a small mass from infinity to that point, with zero potential at infinity.

For an attractive field around a point mass, potential is negative because the field releases energy as the mass moves inward.

Moving a test mass farther from a planet raises its gravitational potential toward zero.

Potential is energy per unit mass, not force; equal potential does not imply equal field strength everywhere.