Hi, I have recently been studying waves, and I understand the transversal wave formula y=Asin(w(t-x/v)) which gives the y coordinate of a point at x along the x-axis in the instant t. However, Wikipedia (http://en.wikipedia.org/wiki/Longitudinal_wave) gives this as the equation for longitudinal waves too. If this is true, what does y represent? The displacement of a point relative to what? Also, does anyone know how to derive this formula specifically for longitudinal waves? Thanks very much!