Increasing and Decreasing of Friction

Key Concepts

1. Increase friction

2. Decrease friction

Introduction 

Friction force opposes or resists the relative motion between the two surfaces of objects in contact. It always acts in the direction opposite to that of the applied force or in the direction opposite to which an object moves or tries to move. It is a contact force. There are ways to increase and decrease friction in daily life. In this session, we will list and explain each one of them.

Explanation:

Increase friction: 

Friction can be increased by increasing the roughness of the surfaces in contact. This will increase the irregularities between the surfaces. 

 There are many ways to increase friction. A few of them are: 

1. Treaded tires of the vehicles to increase the grip on the road. 

2. Football shoes have studs or grooves to have a better grip on the floor. 

3. Kabaddi player wiping hands with sand to have a better grip on the other person 

4. The breaking pads of vehicles are rough to stop moving vehicles when the breaks are applied. 

5. Gymnasts apply some coarse substance on their hands for a better grip. 

Decrease friction: 

Friction can be decreased by reducing the roughness of the surfaces in contact. This will decrease the irregularities between the surfaces. 

 There are many ways to decrease friction. A few of them are: 

1. Using lubricants like powder or oil and grease 

• We sprinkle the powder on a carrom board to reduce friction. 
• Oil or grease is applied between moving parts of machines to reduce friction. 

2. Using rollers or wheels 

• Rollers are used in luggage bags to reduce friction. 
• Wheels are used in vehicles to reduce friction. 

3. Using ball bearings 

• Ball bearings are used in ceiling fans, bicycles and vehicles to reduce friction. 

4. Streamlined body help in reducing the friction. 

5. Polishing the surface to reduce the irregularities. 

Questions and answers 

Question 1: Why do gymnasts or kabaddi players apply a coarse substance to their hands? 

Answer: 

Kabaddi players and gymnasts apply some coarse substance on their hands to improve their grip and prevent slipping. Applying coarse substance increases friction, and hence it helps with better performance. 

Question 2: Why are grooves provided in the soles of shoes and treads made on the surface of tyres?  

Answer: 

A series of patterns made into the surface of a tyre is called tread. They increase the irregularities which in turn gives the tyres better grip on the surface of the road. 

The grooves on the soles of shoes have been designed to increase friction with the ground so that the shoes get a better grip even on a slippery ground and we can walk safely without slipping and getting hurt.  

QUESTION 3: Fill in the blanks: 

1. Sprinkling of powder on the carrom board ___reduces___ friction. 

2. Ball bearings reduce friction because they __roll____ rather than slide. 
3. Oil or grease is applied to those parts of the machine which are in motion to _minimize  friction .  

Summary

1. There are a few ways to increase the friction such as:

a. Treaded tires

b. Studs in football shoes

c. Kabaddi player wiping hands with sand

d. Sole of shoes is grooved

2. There are a few ways to decrease the friction such as:

a. By applying lubricants or oil

b. Using ball bearings

c. Polishing surface

d. Adding wheels