proposal has been made to use a pair of parallel disks to measure the viscosity of a liquid sample. The upper disk rotates at height h above the lower disk. The viscosity of the liquid in the gap is to be calculated from measurements of the torque needed to turn the upper disk steadily. Assuming the velocity distribution in the gap is linear, obtain an algebraic expression for the torque needed to turn the disk. Could we use this device to measure the viscosity of a non- Newtonian fluid