Friction: A Necessary Evil States

Friction is a force of contact which is equally useful and harmful for daily activities. People can walk easily due to friction between the road and footwear. At the same time more friction damages engines. In this concept, the students will understand the importance of friction and know how to increase or reduce it.

After reading the concept, students will be able to:

• Describe the advantages of frictional force.
• State the disadvantage of frictional force.
• Explain the methods of reducing friction.
• Describe how the use of lubricants such as grease oil affects friction.
• Answer- what is ball bearing and mention its uses.
• Recite the methods of increasing friction.

 

Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept Friction Is a Necessary Evil provided in PDF format.

Friction Is a Necessary Evil:

Friction is a force that comes into play when two surfaces come in contact. The frictional force has its share of both advantages and disadvantages. These are briefly described below—

Advantages of Frictional Force:

Many of our daily activities are dependent on the application of frictional force. Some of the examples are listed here.

 

Disadvantages of Frictional Force:

 

Methods of Reducing Friction:

There are many ways to minimise the ill effects of frictional force.

1. Use of Lubricants:

• Substances that can reduce the amount of friction and wear and tear of different objects are called lubricants.

            Examples: Motor oil, gel, silicone, oil, grease, wax etc.

• Grease is used in different parts of automobiles and bicycles to reduce friction and increase efficiency.

 

2. Polishing:

Polishing a surface can make rough surfaces smooth and reduce friction.

 

3. Applying Oil or Powder:

 

4. Using Rollers, Wheels and Ball Bearings:

 

Methods of Increasing Friction:

• The soles of the shoes are grooved, which increases the friction between our feet and the ground, and we can walk properly.
• The tyres of vehicles have treads that allow them to have a grip on the road.
• Gymnasts apply chalk powder on their hands to increase their grip.
• The brake pads of vehicles are coarse, so when breaks are applied, it helps the vehicle stop on the road.
• Kabaddi players rub their hands with soil which increases the friction between the hands and allows them to easily grip the opponent.

 

Viscous Drag:

• Any type of fluid, either a liquid or a gas, exerts a frictional force on the objects. It is called fluid friction.
• The force acting opposite to the motion of any object moving in a fluid is called drag.

• The amount of fluid frictional force on an object depends on the following factors—
• The shape of the object.
• The viscosity of the fluid
• Speed of the object with respect to the fluid.
• We can say that fluid friction exerts a minimum force on a streamlined body.
• So, birds and fish have streamlined bodies that help them move swiftly through air and water, respectively.
• The bodies of aeroplanes, missiles, rockets, and cars are also streamlined to reduce air resistance.
• Ships also have a streamlined shape to reduce friction while moving through water.

 

New Words:

 

Did You Know?

• An inclined plane always reduces the frictional force. The motion of an object reduces on an inclined plane which is why the frictional force that opposes the object’s motion also reduces.