First law of thermodynamics

First Law of Thermodynamics

• When a closed system undergoes a complete cycle net work is done on or by the system. The only other energy involved in the cycle is heat which is supplied or rejected during various processes.
• The first law relates these two forms of energy in the following statement.

"For a closed system undergoing a cycle the net energy interaction in the form of heat is equal to the net energy interaction in the form of work"

(for a closed system undergoing a cycle)

There can be other statements that pertain to first law.

The first law cannot be proved analytically, but experimental evidence have repeatedly

confirmed its validity and it has never been violated. It is a law of nature.