Changes

where <math>\mathrm{d}U</math> is the infinitesimal increase in the internal [[energy]], <math>\delta Q</math> is the infinitesimal amount of [[heat]] added, and <math>\delta W</math> is the infinitesimal amount of work performed.

where <math>\mathrm{d}U</math> is the infinitesimal increase in the internal [[energy]], <math>\delta Q</math> is the infinitesimal amount of [[heat]] added, and <math>\delta W</math> is the infinitesimal amount of work performed.

A ramification of this is the [[Conservation of energy|Principle of conservation of energy]];<ref>Wile, Dr. Jay L. ''Exploring Creation With Chemistry''. Apologia Educational Ministries, Inc. 1998</ref><ref>“This law is considered the most powerful and most fundamental generalization about the universe that scientists have ever been able to make.  No one knows why energy is conserved... All that anyone can say is that in over a century and a quarter of careful measurement scientists have never been able to point to a definite violation of energy conservation, either in the familiar everyday surroundings about us, or in the heavens above or in the atoms within.” Isaac Asimov, Smithsonian Institution Journal, 1970, p.6 [http://www.trueorigin.org/steiger.asp (quoted)]</ref> the amount of energy in the [[closed system]] of the universe remains constant. This can be combined with the principle of [[e=mc^2|Mass-Energy Equivalence]] to demonstrate that the amount of mass in the [[universe]] is constant.

A ramification of this is the [[Conservation of Energy|Principle of conservation of energy]];<ref>Wile, Dr. Jay L. ''Exploring Creation With Chemistry''. Apologia Educational Ministries, Inc. 1998</ref><ref>“This law is considered the most powerful and most fundamental generalization about the universe that scientists have ever been able to make.  No one knows why energy is conserved... All that anyone can say is that in over a century and a quarter of careful measurement scientists have never been able to point to a definite violation of energy conservation, either in the familiar everyday surroundings about us, or in the heavens above or in the atoms within.” Isaac Asimov, Smithsonian Institution Journal, 1970, p.6 [http://www.trueorigin.org/steiger.asp (quoted)]</ref> the amount of energy in the [[closed system]] of the universe remains constant. This can be combined with the principle of [[e=mc^2|Mass-Energy Equivalence]] to demonstrate that the amount of mass in the [[universe]] is constant.

Note that if no energy is added, then the maximum amount of [[work]] that can be performed by the system is equal to its initial energy.  This prevents the existence of a type of [[perpetual motion machine]].

Note that if no energy is added, then the maximum amount of [[work]] that can be performed by the system is equal to its initial energy.  This prevents the existence of a type of [[perpetual motion machine]].