Advertisement

Factors affecting the force of viscosity and Applications on the viscosity

From Online Sciences - November 8, 2017

Viscosity is the property which is responsible for the resistance or friction between the liquid layers and prevents sliding of layers above each other , Some liquids like water and alcohol have high ability to flow & its resistance for motion of objects inside them is small , so , their viscosity is small , Some liquids like honey and glycerin have low ability to flow & its resistance for motion of objects inside it is high , so , their viscosity is large .

Viscosity

When two similar funnels are hung on two holders and a beaker is placed below each , Alcohol is poured in one of them and glycerin in the other , speed of flow of alcohol is higher than that of glycerin , That means the ability of alcohol to flow is higher than that of glycerin .

Two beakers one is filled with water and the other with honey , stir both of them using a spoon then take the spoon out , The spoon moves easier in water which means that the resistance of water to the spoon motion is less than that of the honey , Motion of the honey stops faster than of water after removing the spoon .

Two beakers one is filled with water and the other with glycerin , a small metal ball is gently dropped in both beakers , Calculate the time required by the ball to reach the bottom of the beaker , The ball moves faster in water which means that glycerin resists the motion of the ball more than water .

Explaining the concept of viscosity

Imagine a quantity of fluid confined between two parallel plates , One of them is at rest and the other moves with a velocity ( v ) ,

This is referring to :

This type of flow is called the laminar flow or viscous flow .

Deduction of the viscosity coefficient

Consider two layers of liquid such that the perpendicular distance between them is ( d ) , if force ( f ) acted on the upper layer of the liquid ( its area ( A ) ) and moved it in a velocity ( v ) , then in order that the moving layer keeps its velocity constant , then the tangent force between the two layers of the liquid during its motion ( the force of viscosity ) is :

Directly proportional to A , v : FA , Fv

Inversely proportional to d : F1/d

FAv/dF = constant (Av/d )

F = vs ( Av/d ) , vs = Fd / Av

Factors affecting the force of viscosity :

Applications on the viscosity

Advertisement

Continue reading at Online Sciences »