Solving Transfer of Torque with \mu = 0.38 Ns/m^2

[KillerZ]

Homework Statement

The clutch system shown in Fig. P10-22 is used to transmit torque through a 3-mm-thick oil film with $$\mu = 0.38 N \bullet s/m^{2}$$ between two identical 30-cm-diameter disks. When the driving shaft rotates at a speed of 1450 rpm, the driven shaft is observed to rotate at 1398 rpm. Assuming a linear velocity profile for the oil film, determine the transmitted torque.

Homework Equations

$$T = \mu\left(\frac{4\pi^{2}R^{3}\dot{n}L}{l}\right)$$

The Attempt at a Solution

$$\mu = 0.38 N \bullet s/m^{2}$$
$$L = 30cm = 0.3m$$
$$l = 3mm = 0.003m$$

This is where I am stuck I am not sure what R is. I think I have to find T for the two rpms and find the difference between them for the transferred torque.

 

[CFDFEAGURU]

The units should tell you what R is. You have to get N-m out of this equation, so based on what you know (the given values) you can figure out what unit R will have and that will tell you what it's value should be.

Thanks
Matt