Entropy and energy in competition

Abstract

Equivalent to the growth of entropy in an adiabatic body is the decrease of the available free energy in a body whose boundary is kept at a constant temperature. The form of the available free energy depends on the nature of the working on the body. The working of conservative body forces may be represented by a potential energy but the working on the boundary of the body may assume quite a variety of forms. Special cases are

• no working, when the surface of the body is at rest

• working by a dead load.

Generally the available free energy contains an energetic part and an entropic part. And when the free energy assumes a minimum, we may consider this as a compromise between the energy which tends to a minimum and the entropy which tends to a maximum. Those two tendencies — the energetic and the entropic one — often compete, since generally the energy favours a different distribution of matter than the entropy.