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## Homework Statement

The velocity distribution of a fluid in two 0.3m long rotating cylinders is given by u=0.4/r-1000r (m/s). The diameter of the cylinders are 2cm and 4cm. If the inner cylinder rotates at 500rpm the power on the inner cylinder is measured to be 1Watt. Find the viscosity of the fluid?

## Homework Equations

P=τ . ω

Torque = μ x ((ω . R1)/(R1-R0))

## The Attempt at a Solution

So far my only attempt has been to converting the rpm and power output to find a torque value and then use this to find a viscosity, however, this brings me to a negative value?

torque = 1/52.36 = 0.0191

viscosity = (0.0191)(1-2)/1 = -0.0191

I also understand that the velocity distribution is not linear, however, do not understand how this works into finding the answer. Any help would be great! Thanks!