Write equation of displacement of an element of medium in harmonic wave,

Explanation

The displacement function for a longitudinal wave is written as `, s (x,t) = a sin (kx - omega t + phi)` where `s (x,t)` is the displacemetn of an element of the medium in the direction of propagationof the wave at pposition x and time t. Other quantities have the same meaning as in case of a transverse wave.