Show that the volume that the volume strain in any longitudinal wave is given by (-dy/dx), where y is the displacement at the plane x. Hence show that for a harmonic wave of amplitude A and wavelength `lambda` in a medium of elasticity E, the excess pressure is given by
`p=EA(2pi)/(lambda)sin2pi((t)/(T) - (x)/(lambda))`
Deduce the pressure amplitude, if
`E=1.6xx10^(3)Nm^(-2), A=4xx10^(-7)m` and `lambda=0.5m`.