# Understanding Absolute Viscosity - shearing stress

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1. Jan 4, 2017

Understanding Absolute Viscosity - shearing stress
Hi everyone,
I have found information about Absolute viscosity:

Coefficient of absolute viscosity is a measure of internal resistance. Dynamic (absolute) viscosity is the tangential force per unit area required to move one horizontal plane with respect to an other plane at an unit velocity when maintaining an unit distance apart in the fluid.

The shearing stress between the layers of a non turbulent fluid moving in straight parallel lines can be defined for a Newtonian fluid. Now my question is what is shearing stress and how to measure it? What is the relationship between Absolute and Kinematic Viscosity?
which units I can use for Absolute and Kinematic Viscosity?

2. Jan 4, 2017

### Staff: Mentor

Shearing stress is the sideways force per unit area that you have to apply to the plates. You measure the force required, and divide by the plate area.

Kinematic viscosity is equal to absolute viscosity divided by density
Absolute viscosity: $\frac{gm}{cm-sec}$

Kinematic viscosity: $\frac{cm^2}{sec}$

3. Jan 4, 2017

Thanks Chestermiller.

But I have another questions regarding shearing force & viscosity,

1) A fluid is flowing between two layers. Calculate the shearing force if the shear velocity is 0.25 m/s and has length 2 m and dynamic viscosity is 2Ns/m$^2$.

2) What's the physical meaning of these two viscosity ?

Last edited: Jan 4, 2017
4. Jan 5, 2017

### Staff: Mentor

I don't see any attempt on your part to solve Problem 1. For Item 2, what does your textbook say?