The study of the transformation of energy into other manifested forms and of their practical applications. Commonly encountered forms of the statements of the three principal laws of thermodynamics are: (0) The heat capacity and entropy of every crystalline solid becomes zero at absolute zero (0 degrees Kelvin). (1) The Law of the Conservation of Energyenergy may be transformed in an isolated system, but its total is constant. (2) Heat from a reservoir at a constant temperature cannot be changed completely into work by a cyclic process.