Question 1 What makes the steps of foot over bridges at railway station to wear out slowly?
Question 2 Which part wear away first in shoe? Give a reason for your answer?
Question 3 Why do brake pads of bicycles have to be replaced quite often?
Question 4 A pencil eraser loses tiny pieces of rubber each time you use it. Why does this happen?
Question 5 What happen when you rub your hands vigorously for few seconds. Why does this happen?
Question 6 Explain why soles of shoes wear out gradually?
Question 7 Why tyres of vehicles wear out gradually?
Question 8 State few disadvantages of friction?
Question 9 Why brake pads wear out gradually?
Question 10 How friction reduces the efficiency of machines?
Question 11 How friction damages the machine parts?
- 1 (1) Friction wears away the soles of our shoes
- 2 (2) The tyres of vehicles wear out gradually due to friction
- 3 (3) Friction wears out the rubbing machine parts
- 4 (4) Friction wears out the brake pads of vehicles gradually
- 5 (5) Friction wears out steps of staircases in buildings and foot over-bridges
- 6 (6) Friction produces heat which may damage machines
- 7 (7) Friction reduces the efficiency of Machines
- 8 (8) Friction slows down motion
(1) Friction wears away the soles of our shoes
When we walk on the road, there is friction between the soles of our shoes and the surface of road. When the soles of shoes rub against the rough surface of road, then tiny pieces of the soles keep on breaking off slowly due to which the soles of our shoes wear out gradually. The wear and tear of the soles of our shoes ultimately causes holes in the soles. The shoes get damaged and become unfit to wear.
(2) The tyres of vehicles wear out gradually due to friction
When the vehicles run on the road, there is a friction between the surface of tyres and the surface of road. The rubbing of tyres with road keeps on breaking tiny pieces of rubber from the tyre’s surface gradually. All the treads present on the surface of a tyre are worn out and the tyre becomes baldy. Such baldy tyres have to be replaced by new tyres.
(3) Friction wears out the rubbing machine parts
Due to friction the rubbing parts of a machine wear out gradually. Friction also wears out moving parts like ball bearing of bicycles.
(4) Friction wears out the brake pads of vehicles gradually
When the brakes of a vehicles are applied, a lot of friction is produced between the brake pads and moving part of the wheel. This friction wear out the brake pads gradually. Due to this the brake pads of vehicle have to be replaced quite often. The brake pad gets worn out due to friction between brake pad and moving rim of bicycle wheel.
(5) Friction wears out steps of staircases in buildings and foot over-bridges
When a lot of people use the staircase in a building everyday, the friction between soles of their shoes and the stone steps wears away hard stone steps very very slowly. The steps of foot over bridges at railway station wear out due to the friction caused by the shoes of extremely large number of people who use these over bridges all the time.
(6) Friction produces heat which may damage machines
If we rub our hands together quickly for few second, they feel cold. This is because friction between the hands produce heat.
When we operate a mixer and grinder for few minutes, its jar becomes hot. Heat is produced by friction.
When the moving parts of a machine rub together, a lot of heat is produced due to friction between them. This heat may damage the machine gradually.
(7) Friction reduces the efficiency of Machines
Some of the energy supplied to run a machine is wasted in overcoming friction between its moving parts and some of the energy is wasted in heat generated by the machine. This wastage of energy reduces the efficiency of a machine.
(8) Friction slows down motion
Friction reduces the motion of moving parts of a machine. All the moving things are slowed down by friction.