The first law of thermodynamics is a version of the law of conservation mathematische Abhandlungen (Classic Reprint) PDF energy, adapted for thermodynamic systems. An equivalent statement is that perpetual motion machines of the first kind are impossible.
Författare: Julius Edward Czwalina.
Investigations into the nature of heat and work and their relationship began with the invention of the first engines used to extract water from mines. Improvements to such engines so as to increase their efficiency and power output came first from mechanics that worked with such machines but only slowly advanced the art. Deeper investigations that placed those on a mathematical and physics basis came later. The first law of thermodynamics was developed empirically over about half a century. Rankine’s statement is considered less distinct relative to Clausius‘.
In 1840, Germain Hess stated a conservation law for the so-called ‚heat of reaction‘ for chemical reactions. Julius Robert von Mayer in 1841 made a statement that meant that „in a process at constant pressure, the heat used to produce expansion is universally interconvertible with work“, but this is not a general statement of the first law. The original nineteenth century statements of the first law of thermodynamics appeared in a conceptual framework in which transfer of energy as heat was taken as a primitive notion, not defined or constructed by the theoretical development of the framework, but rather presupposed as prior to it and already accepted. The first explicit statement of the first law of thermodynamics, by Rudolf Clausius in 1850, referred to cyclic thermodynamic processes.