Mass, internal energy, and Cauchy's equations in frame-indifferent thermodynamics (Q807074)

The balance equations of linear and angular momenta are derived from the balance of energy and from the principle of material frame-indifference. Also other well-proved concepts are not taken for granted: the concept of mass, the classical expression for the acceleration force, the splitting of the energy into its internal and kinetic part, and the classical transformation law for the external force. The result is at least surprising because material frame-indifference states transformation properties of qualities when changing the observer and includes no information about evolution equations, and the energy balance is one equation which cannot determine the six equations for linear and angular momentum.