Q. 9. Give examples to show that
friction is both a friend and a foe.
Answers
Examples to show that friction is a friend and a foe: Friction is friend: (i) Friction allows us to grip and catch different objects. (ii) It helps us to walk comfortably on the surface. (iii) It helps to minimize the speed or to stop the moving objects. (iv) It helps us to write on paper or blackboard. (v) The things do not move from their places if we do not want to move, due to friction. Friction is foe: (i) Friction causes wear and tear in objects. (ii) It causes damage to the parts of machines. (iii) The machines or tools regular maintenance due to which a lot of money is wasted. (iv) It reduces the speed of moving objects so more force is required. (v) It does not allow the free movement of objects.
Answer:
Friction plays a very important role in our daily life. In some cases friction is useful and in some cases friction is harmful and we have to find ways to overcome it.
Friction as a friend:
1. Friction enables us to walk without slipping.
2. Friction enables a car to move on road without skidding.
3. Friction enables us to apply brakes and slow down a moving vehicle.
4. Friction enables us to write and draw on paper.
5. Friction enables us to pickup and hold things in our hands.
6. Friction enables us to light a matchstick.
Friction as Foe:
1. Friction wears away the soles of our shoes.
2. The tyres of vehicles wear out gradually due to friction.
3. Friction wear out the machine parts.
4. Friction produces heat which damage machine parts.
5. Friction reduced the efficiency of machines.
6. Friction slows down the motion of machines and we have to use oil and lubricants which causes more expenditures.
N.B: I have to answer from school/ college syllabus.