[P2.5]
is: a measure of its capacity to do work. [P2.4]
can exist: in several different forms. The energy that a body has because of its motion is called its kinetic energy (see also rotational, translational and vibrational kinetic energy); while energy arising from its position in relation to other bodies with which it is interacting or from its internal configuration is called its potential energy (see also electrical, gravitational and strain potential energy). [P2.4, P2.5]
is sometimes named: to reflect the situation in which it arises, e.g. mechanical energy, acoustic energy, heat and mass energy.
remains: for an isolated system, constant in sum over all its different forms, according to the principle of conservation of energy (see also first law of thermodynamics). [P2.4, P2.5]
may be converted: from one form into another, subject to various limitations (see also second law of thermodynamics). [P2.4, P2.5]
is: a scalar quantity, with dimensions [P2.5]
has as its SI unit: the joule (J), where 
[P2.4. P2.5]
See also equipartition of energy and internal energy.
Copyright 1997, The Open University