A Newtonian fluid is in laminar flow in a rectangular duct as shown in the figure. The fluid motion is due to gravity and a pressure difference in the vertical direction between the level at z = 0 and z = L. Assume the system is at steady-state and that the fluid is incompressible. Beginning with a microscopic momentum balance and using the coordinate system shown in the diagram:

a) Total volume flow rate b) Drag force exerted by the fluid on each wall Also plot the qualitative shear stress and velocity profiles for the entire flow both on conventional graphs and superimposed on the geometry.