An amazing number of commercial and laboratory devices have been developed to

measure fluid viscosity, as described in Ref. 29 and 49. Consider a concentric shaft, fixed

axially and rotated inside the sleeve. Let the inner and outer cylinders have radii ri and ro,

respectively, with total sleeve length L. Let the rotational rate be 2 (rad/s) and the applied

torque be M. Using these parameters, derive a theoretical relation for the viscosity of the

fluid between the cylinders.