A large plate is pulled at a constant speed of U = 4 m/s over a fixed plate on 8-mm-thick engine oil film at 20°C. Assuming a half-parabolic velocity profile in the oil film, while the flow is developing as illustrated, determine the shear stress on the upper plate and its direction. Repeat for the linear profile (dashed line) that develops after a long time. (Take the dynamic viscosity of oil as 0.8374 Pa·s.)What would happen if a linear velocity profile were assumed?