# Fluids (Viscosity)

1. Sep 17, 2007

### suspenc3

1. The problem statement, all variables and given/known data

A flat plate viscometer consists of a disc of diameter 50mm rotating at 300rpm in close proximity to a fixed horizontal plate. When the gap between the plates is 0.1mm, it is found that the torque required to drive the disc is 0.2Nm. What is the viscosity of the liquid between the plates?

3. The attempt at a solution

First I found the angular velocity to be 31.41 rad/sec, and then used U=rw to find the constant velocity (r=radius, w=angular velocity)

Next i used $$\tau = \mu(U/t)$$, knowing the torque, velocity and gap thickness to give me the viscosity $$\mu$$

Does this look somewhat right?

2. Feb 21, 2015

### Saurav.1905

Can we try F= μ (dv/dx) a, where a - area , μ - viscosity...
converting 31.41 rad/s (given) into liner velocity
Just high level thought... Not sure i am not correct path....

3. Feb 21, 2015

### Staff: Mentor

Show more of the details. I can't tell you whether you did it right until I see your derivation of the algebraic equation for the torque.

Chet

4. Feb 21, 2015

### Staff: Mentor

This was a post from 2007, and the member who originally posted this had not been back since. I think 8 years is enough. I'm closing this thread.

Chet