where ???? is the viscosity of glycerine, ????P ????x is the pressure gradient in the direction of flow and y is the distance from the lower plate. if ????P ????x is 745 pa/m, calculate a) the distance from the lower plate (in cm) where the shear stress is zero and b) the magnitude (pa) and direction of the stress exerted by the fluid on the top and bottom plates. μglycerine