Stability and the 2nd law

This video introduces the second law of thermodynamics, the entropy principle.

The second law is concerned with the conversion of heat into work and the quality of energy. The quality of energy indicates the amount of useful energy that can do work among the conserved total energy. There are various statements expressing the second law. One is involved with the entropy of the isolated system. The other is for the equilibrium. The last statement present the criteria for reversibility.