Two parallel surfaces move relative to each other are separated by a gap of 0.375 in. The gap is filled by a fluid of with .00431 lb-sec/in2 viscosity. The relative motion is resisted by a shear stress of 0.25 lb/in2 due to the viscosity of the fluid. What is the velocity of the parallel surfaces above assuming the velocity gradient in the space between the surfaces is constant?

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?