Potential Energy of a System in Physics

Potential energy is stored work, and it only exists because two or more things are arranged in a particular way. That is why the symbol always belongs to a system and never to a single body. Raise a mass and you store the work you did against gravity. Stretch a spring and you store the work you did against its restoring force. In both cases the storage is only trustworthy because those forces are conservative, which is the property that lets a stored amount be read off from the configuration alone, with no record of the route that produced it. The blocks give the two stored forms, the general interval form, and the two way link between a conservative force and the potential energy it comes from.