势能
Potential energy is closely linked with forces. If the work done by a force on a body that moves from "A" to "B" does not depend on the path between these points (if the work is done by a conservative force), then the work of this force measured from "A" assigns a scalar value to every other point in space and defines a scalar potential field. In this case, the force can be defined as the negative of the vector gradient of the potential field.