need to answer a,b,c three questions step by step

In this problem we wish to determine the viscosity of a fluid in the narrow annulus between a stationary cylinder (bob) and a rotating cup. The bob has a radius of r1 and the cup has a radius of r2. The height of the fluid in the cup is L, and the cup rotates with an angular speed of 0. a) Determine the velocity profile of the fluid in the annular region. Assume that L(r2r1), such that the flow is unidirectional. (Hint: the velocity of a rotating surface equals the angular velocity multiplied by the radius.) b) Calculate the force on the bob (inner cylinder) due to the rotating fluid. c) The torque, T, that the inner cylinder exerts on the fluid equals the force on the bob multiplied by the lever arm (i.e. the radius at which the force is applied). Assuming the torque is a known quantity (i.e. you know the torque required to spin the cup at 0 ), write an expression for fluid viscosity in terms of known or measurable quantities