A plane wave = a cos (cot kx) propagates in a homogeneous elastic medium. For the moment t = 0 draw. (a) The plots

A plane wave ε = a cos (cot – kx) propagates in a homogeneous elastic medium. For the moment t = 0 draw.
(a) The plots of ε, ∂ε /∂t, and ∂ε /∂x vs x;
(b) The velocity direction of the particles of the medium at the points where ε = 0, for the cases of longitudinal and transverse waves;
(c) The approximate plot of density distribution p (x) of the medium for the case of longitudinal waves.