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Friction : Why it is necessary?

Grade 3
Aug 20, 2022

key Concepts

  • Friction
  • Is friction necessary


When we stop pedalling a bicycle, it slows down for some time and eventually stops. Similarly, if a moving football is not kicked again, it slows down for some time and eventually stops. Based on these illustrations, one can conclude that objects do not keep moving forever. They stop after slowing down for some time. This happens because moving objects experience friction, which arises when two objects rub against each other. 



When a moving object rubs against another, it slows down and eventually stops. This rubbing action results in a force called “friction”, which slows down the moving body and eventually stops it. 

Example: A moving bicycle slows down and stops quickly when its brakes are applied. When the hand brakes are applied, the brake pads near the tyres rub against the rim. This gives rise to friction, which slows down the motion of the tyres and eventually stops it.  

Function of bicycle brakes 
Function of bicycle brakes 

Friction is a force that makes moving objects slow down and/or stop. It occurs between two objects which rub against each other.  


The friction is the highest when two rough surfaces rub against each other. For example, when a wooden box is moved on a cemented floor, the friction is high. This is because the surface of a wooden box and the cemented floor are rough. 

Friction due to two rough surfaces rubbing against each other

Friction is less when a smooth surface rubs against a rough surface. For example, walking on a patch of ice. The surface of the ice is smooth, whereas the surface of the shoes is somewhat rough. Hence, the friction is less. 

Friction due to a rough and a smooth surface rubbing against each other

Friction is the least when two smooth surfaces rub against each other. Two polished or lubricated surfaces freely slide on each other, as there is the least friction between them. 

Is friction necessary?  

Friction is necessary, as we are able to perform various day to day actions with ease. For example, we are able to walk properly because of the friction between the soles of our shoes and the road. It is difficult to walk on ice, as ice has a smooth surface that offers less friction. An iron nail remains stuck in the wall because of the friction between the nail and the wall. An eraser is able to erase the pencil marks because of the friction between the eraser and the paper. A sandpaper is used to smoothen out the surface of wooden articles. This technique works because of friction. We are able to brush our teeth and remove all the dirt in them because of the friction between the bristles and the teeth. The spectacles stay on our noses because of friction between the spectacles and our skin. 

Desirable consequences of friction 1
Desirable consequences of friction 2
Desirable consequences of friction 3
Desirable consequences of friction 4
Desirable consequences of friction 5

However, there are a few undesirable consequences of friction. For example, the wear and tear of the soles of the shoes over time is due to the friction they go through for a long time. The surface of the tyres of vehicles wears out on prolonged usage. This is because of the friction between the road and the surface of the tyres. 

Undesirable consequences of friction 1
Undesirable consequences of friction 2
Undesirable consequences of friction 3
Undesirable consequences of friction 5

Questions and answers 

  1. Arrange the following surfaces in the descending order of the amount of friction that they offer. 
  1. Wooden table 
  1. Mirror 
  1. Wall  
  1. Road 
Question 1
Question 2


The amount of friction offered by a surface depends on its roughness.  

Thus, the surfaces can be arranged in the descending order of the amount of friction that they offer as follows. 

Road > wall > wooden table > mirror 

  1. A girl hits a golf ball aiming towards the hole. However, the ball stopped before reaching the hole. Give reasons for this
Question 2 


The golf ball could not reach the hole because of friction. It slowed down and eventually stopped it.  

The surface of the ball rubbed against the ground, which gave rise to the friction. 


1. A rubbing action between two surfaces results in friction.

2. Friction is a force that slows down and stops a moving object.

3. The friction is the highest when two rough surfaces rub against each other.

4. The friction is lesser when a smooth surface rubs against a rough surface.

5. The friction is the least when two smooth surfaces rub against each other.

6. Friction generates heat between the surfaces in contact.

7. Friction is necessary for us, as it helps us walk, run and perform various activities with ease.

8. However, there are some undesirable consequences of friction, such as wear and tear of shoes and tyres of vehicles.


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