Coefficient of viscosity

Definition

The coefficient of viscosity is a measure of a fluid's resistance to flow. It quantifies the internal friction within the fluid.

5 Must Know Facts For Your Next Test

1. The unit of coefficient of viscosity in the SI system is Pascal-second (Pa·s).
2. Viscosity decreases with increasing temperature for most liquids but increases for gases.
3. Newtonian fluids have a constant coefficient of viscosity, while non-Newtonian fluids do not.
4. The coefficient of viscosity can be determined experimentally using viscometers or rheometers.
5. Stokes' law relates the force experienced by a spherical object moving through a viscous fluid to the fluid's coefficient of viscosity.

Review Questions

• What is the SI unit for the coefficient of viscosity?
• How does temperature affect the coefficient of viscosity in liquids and gases?
• What distinguishes Newtonian fluids from non-Newtonian fluids regarding their coefficients of viscosity?

Related terms

Newtonian Fluid:

A type of fluid whose viscosity remains constant regardless of applied stress.

Non-Newtonian Fluid:

A type of fluid whose viscosity changes when stress or shear rate is applied.

Stokes' Law:

$$F = 6 \pi \eta r v$$, where \( F \) is the drag force, \( \eta \) is the coefficient of viscosity, \( r \) is the radius of the sphere, and \( v \) is its velocity.