3.1-2 Shear Stress and Shear Rate in Fluids. Using Fig. 3.1-1, the lower plate is being pulled at a relative velocity of 0.40 m/s greater than the top plate. The fluid used is water at 24C. a. How far apart should the two plates be placed so that the shear stress is 0.30 N/m? Also, calculate the shear rate. b. If oil with a viscosity of 2.0 10-2 Pa s is used instead at the same plate spacing and velocity as in part (a), what are the new 116 shear stress and the shear rate?