# Solid Friction and Viscosity Similarities & Dissimilarities

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Contents

## What is Friction?

Friction is the force that opposes the motion. It acts between the surfaces in contact.

There are basically four types of frictions-

• Static Friction
• Sliding
• Rolling Friction
• Fluid Friction

### Definition of Solid Friction

The friction that acts between the surfaces of solid surfaces. Static, Sliding and Rolling Frictions are the examples of Solid Frictions.

Also Read: Chapter 12 Friction Class 8 Notes Pdf

## Viscosity Definition

It is the internal friction of fluid flow. It is the measure of fluid’s resistance to flow.

### Dissimilarities Friction Viscosity

Let us look at the differences or dissimilarities of Solid Friction and Viscosity.

• Viscous force is directly proportional to the relative velocity of the layers of liquid under consideration whereas Solid Friction is independent of the relative velocity of bodies in contact.
• Viscosity is proportional to the surface area of contact of liquid layers whereas Solid friction is independent of the area of surfaces in contact.
• Viscosity does not depend on the normal reaction between the two layers in contact but Solid Friction does.

### Similarities Friction Viscosity

Let us look now at the similarities of Solid Friction and Viscosity.

• Both oppose the motion.
• Both acts tangentially in the opposite direction of motion.
• The result of intermolecular forces. Both oppose the motion.

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