  For steady-state and some other types of mechanical waves of an arbitrary
form, intensity and nature, propagating in a free uniform waveguide, we present
the following. Relations for the axial momentum as it directly follows from the
conservation laws. The mass associated with the wave. The connection between
the wave energy and momentum. The structure of a binary wave which possesses a
self-equilibrated momentum, in particular, a transverse-longitudinal wave
formed upon excitation of flexural waves. Conditions under which longitudinal
sinusoidal waves can carry momentum and the physical meaning of the so-called
"wave momentum".
