can E2 work with heat
The internal energy is a state variable, just like the temperature or the pressure. The first law of thermodynamics defines the internal energy (E) as equal to the difference of the heat transfer (Q) into a system and the work (W) done by the system.E2 - E1 = Q-W We have emphasized the words into and by in the definition.hermodynamics is a branch of physics which deals with the energy and work of a system. Thermodynamics deals only with the large scale response of a system which we can observe and measure in experiments.