There are two .25 m long concentric cylinders in a viscometer. Only the inner cylinder is rotating. THe velocity distribution is given by V(r)=1000r-0.4/r [m/s]. If the diameters of the cylinders are 3 cm and 5 cm, respectively, what is the fluid viscosity if the torque on the inner cylinder is measured to be 0.0026 Nm?