What is friction

It is a force which opposes motion of one object over another object in contact with it

In easy language,it is a force which makes moving object stop


Example 1

A ball which is moving comes to rest after some time

This is due to force of friction between ball and ground

Ball stopping itself

Example 2

Boat comes to rest if we stop rowing

This is because of the force of friction between water and the boat

Boat stops moving after rowingstops

What is direction of force of friction?

Friction always acts in the opposite direction of motion

If we push a book on table from left to right 

Force of friction moves in opposite direction from right to left

Similarly, if we push a book on table from right to left

Force of friction moves in opposite direction from left to right


What causes friction?


If we take a microscope and zoom in the surface of two objects,

we see that both the surface have some irregularities

When we try to move the object, the irregularities gets interlocked. This causes friction


rougher the surface, more the irregularities. Hence, more friction

smoother the surface, less the irregularities. Hence, less friction

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  1. Class 8
  2. Chapter 12 Class 8 - Friction

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.