First Axiom of Thermodynamics

1.3 First Axiom of Thermodynamics

\begin{equation*} \begin{array}{ccccc} dU & = & \delta Q &-& dW \\ \mbox{Change of the inner energy} & = & \mbox{heat energy (into system)} &- &\mbox{work (performed by system)} \end{array} \end{equation*}

(1.2)

\(\delta Q\):

heat energy
not!! heat stuff: A scientific letter of the 19. century:
Blacksmith uses a hammer to form metal; the metal gets warm;
the heat stuff flows from the hand into the metal;
as a consequence the hand and the head of the blacksmith become cold!

energy is conserved
not force (as was successfully introduced by Newton’s mechanics \( F = m a\)) but energy is the new fundamental concept of physics
which force belongs to the heat energy? (later)

Example:

\begin{equation*} U_{2} - U_{1} = Q - W \end{equation*}

(1.3)

p.s. \(pV\)-diagrams have been a company secret of James Watt for several years.
Thus he had a monopoly for good heat transforming machines.