The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Energy has several forms (e.g. thermal, mechanical, nuclear and electric), some of which are easily convertible and can be changed to another form useful for work. Heat energy is usually measured in British thermal units (Btus) while electrical energy is usually measured in kilowatt-hours (kWh).

Last modifed Monday, December 18, 2006.