A discussion of the validity of hydrodynamical equations of motions

Abstract

Starting from the eqts. (1) and (4) resp. (19) which are valuable for the streaming of an ideal gas in the space, where the plane resp. spheric wave is propagated adiabatically, it follows that for such a motion instead of the Euler's equation the eqts. (11) resp. (20) are valid. In the discussed cases the eqts. (1), (4) and (19) are the fundamental equations and reflect the Newton's principles of dynamics. In our two special cases the one dimensional Euler's equation follows from the fundamental eqts. (1), (4) and (19) only approximately.