Page 1 - Lesson Notes
P. 1
SAI INTERNATIONAL SCHOOL
Class8
Lesson notes
Subject-Physics
CH-Friction
Subtopic-Friction , a necessary evil
Friction: A Necessary Evil
Frictional force plays an important role in our daily life. In some cases, friction is useful
and we want to keep it but in other cases friction is harmful and we wish to reduce it.
Examples:
1. Friction enables us to walk without slipping but it also causes wear and tear of our
shoes.
2. Friction enables a car to move on road without skidding but due to friction the tyres
of the car wears out gradually.
3. Friction is necessary for the working of machine but it also generates heat which
may damage the machines. Energy is required to overcome the friction which also
leads to wastage of energy.