Consider energy exchange in fully developed laminar flow between parallel plates, as in Eqs. (6.63). Let the pressure drop over a length L be?p. Calculate the rate of work done by this pressure drop on the fluid in the and compare with the integrated energy dissipated due to the viscous function from Eq. (4.50) over this same region. The two should be equal. Explain why this is so. Can you relate the viscous drag force and the wall shear stress to this energy result?