9
Question Question 9
Give examples to show that friction is both a friend and a foe.
Friction as a friend :
- We are able to walk on floor due to friction between floor and our feet.
- We are able to write due to friction between pen and paper.
- An object in motion will never stop if there is no friction.
- Without friction between tyres of automobiles and roads, they could not be started, stopped or turned to change direction of motion.
- Friction helps us to tie a knot.
Friction as a foe :
- It wears out the materials like screws, ball bearing or soles of shoes.
- Friction produces heat and so the jar of mixer becomes hot when it runs for a few minutes.
- Friction slows down moving objects, hence, more force is required.
- Due to friction blades of scissors or knives become blunt.
- Due to increased friction between tire and the road surface, when the tire deflates, it becomes difficult to move the vehicle.