In physics, energy (from the Greek - energeia, "activity, operation", from - energos, "active, working")'s a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that's subject to a conservation law. Eight different forms of energy exist to explain all known natural phenomena. These forms include (but aren't limited to) kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The f… (More on Energy)