The New Student's Reference Work/Viscosity of Liquids

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Viscos′ity of Liquids, a term employed in physics to describe a kind of friction between the particles of a liquid when the various parts of the liquid are moving with different velocities. If a surface of area, A, in the liquid be chosen in a plane parallel to one of the fixed walls of the vessel, then the viscosity of the liquid is expressed as follows: Let V denote the velocity with which the liquid is moving at the surface A; and let D be the distance from the surface A to the fixed parallel wall.

Then if R is the tangential resistance experienced by the plane A,

where n is a constant for any one liquid and is called the coefficient of viscosity for that liquid. This coefficient is the measure of the viscosity of any liquid. It is the viscosity of water that causes waves to die down after a storm.