Gravitational Potential and Potential Energy

In earlier study, potential energy was introduced as the energy an object possesses because of its POSITION or CONFIGURATION within a system -- 'configuration' referring to how the various parts/particles of the system are arranged relative to one another. More precisely, potential energy is the work done AGAINST a conservative force (or set of forces) in bringing a system to a particular configuration; it is always a property of the relative positions of the interacting bodies, never of a single isolated body on its own.

A universal principle underlies this idea: every physical system naturally tends to configure itself so as to MINIMISE its potential energy. Changing a system away from its minimum-energy configuration therefore always requires doing work on it (from some external agent). Two everyday illustrations make this concrete: a spring in its natural, unstretched state has minimum elastic potential energy, and stretching or compressing it (doing work against the elastic restoring force) increases that energy, which is released again as the spring snaps back to its natural length; similarly, an object resting on the Earth's surface, together with the Earth, forms a system at minimum GRAVITATIONAL potential energy, and lifting the object (doing work against gravity) increases the system's potential energy, giving the object a stored capacity to do work (or gain kinetic energy) if released and allowed to fall. …