For two $0\mathrm{.}2$ft long concentric cylinders, the velocity distribution is given by u$($r$)=0\mathrm{.}4/$ r $-1000$rm $/$ s If the diameters of the cylinders are lin and $2$in$,$ respectively, the torque in the inner cylinder is measured and found to be $0\mathrm{.}00026$ Nm$.$

Determine: The viscosity of the fluid in $[$cP$]$