The First Principle of Thermodynamics

Abstract

Let us consider a system which undergoes a change while contained in an adiabatic enclosure. This change may be brought about by different processes. For instance, we may increase the temperature T_l of a given mass of water to a temperature T₂ > T₁ by causing some paddles to rotate in the water, or by letting electrical current pass through a wire immersed in the water. In both cases external forces have performed a certain amount of work upon the system.