10. An incompressible Newtonian fluid flows steadily between two infinitely long, concentric cylinders as shown in the figure below. The outer cylinder is fixed, but the inner cylinder moves with

a longitudinal velocity Vo as shown.The pressure gradient in the axial direction is -seltap/l. For what value of Vo will the drag on the inner cylinder be zero? Assume that the flow is laminar, axis symmetric, and fully developed.