# Force & Viscosity between two parallel plates

1. Sep 2, 2010

### Fleawest

1. The problem statement, all variables and given/known data
A flat circular disc of radius 1.0m is rotated at an angular velocity of 0.65 rad/sec over a fixed flat surface. An oil film separates the disk and the surface. If the viscosity of the oil is 16 times that of water (20 degree C) and the space between the disk and the fixed surface is 0.5mm, what is the torque required to rotate the disk?

2. Relevant equations

(T/A) = viscosity(dv/dy)

Where,
T= Shear Force
A= Area of the plate
v= velocity
y= gap between plates

3. The attempt at a solution

A= pi(0.5)^2= 0.7854 m^2
y= 5e-4 m
Viscosity = 16(1.002e-3) = 16.032e-3 N*sec/m^2

How do I turn the rad/sec into shear force and thus torque?

Solving I get T = (0.7854)(16.032e-3)(0.65/5e-4) = 16.37 N*Rad/m

I'm at a loss from here.

Last edited: Sep 2, 2010
2. Sep 2, 2010

### Fleawest

Nevermind, I've got it figured out. I went about it completely wrong. The answer I have now is 2.05 N*m.