Discussion on the first law of thermodynamics

Abstract：In thermodynamics teaching, it is usually a statistics meaning of the second law of thermodynamics in terms of microcosmic, yet, it doesn't make microcosmic explanation to the first law of thermodynamics.The authors take the perfect gas as the thermodynamics system and use the kinetic theorem of particle system, the universal law of energy transfer and conservation are obtained, and an explanation to the first law of thermodynamics in terms of microcosmic is given.The micro essence of the internal energy, caloric and work are revealed.

Keyword：kinetic energy;mass center;internal energy;thermodynamics system;