# NCERT Solutions for Class 8 Science Chapter 12 Friction

You will find NCERT Solutions for Class 8 Science Chapter 12 Friction here that will help you in completing homework on time. These NCERT Solutions for Class 8 are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. It can be used to enrich knowledge and make lessons for learners more exciting. It is very challenging to score good marks in tests that is why we have prepared NCERT Solutions.

Chapter 12 Friction Class 8 Science NCERT Questions and Answers help you in improving the marks in the examinations and have edge over your classmates. Through these NCERT Solutions, students should not waste time and adopt a strategy that helps them operate and learn at maximum efficiency. It will improve your awareness skills sharply and you can easily memorize more things precisely.

## NCERT Solutions for Class 8 Science Chapter 12 Friction

NCERT Textbook will provide you with a lot of interesting topics thus these NCERT Solutions for Class 8 will be useful in understanding in depth concepts well. It is very challenging to score good marks in tests that is why we have prepared NCERT Solutions for Class 8 Science Chapter 12. It will make you well versed in variety of topics and you will be able to instantly recollect your ideas and shape your answers.

Study Material for Class 8 Science Chapter 12 Friction

Page No: 155

Exercise

1. Fill in the blanks.
(a) Friction opposes the ________between the surfaces in contact with each other.
(b) Friction depends on the _________of surfaces.
(c) Friction produces _________.
(d) Sprinkling of powder on the carrom board ________friction.
(e) Sliding friction is ________than the static friction.

(a) Friction opposes the motion between the surfaces in contact with each other.
(b) Friction depends on the nature of surfaces.
(c) Friction produces heat.
(d) Sprinkling of powder on the carrom board reduces friction.
(e) Sliding friction is less than the static friction.

2. Four children were asked to arrange forces due to rolling, static and sliding frictions in adecreasing order. Their arrangements are given below. Choose the correct arrangement.
(a) rolling, static, sliding
(b) rolling, sliding, static
(c) static, sliding, rolling
(d) sliding, static, rolling
► (c) static, sliding, rolling

3. Alida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing orderwill be
(a) wet marble floor, dry marble floor, newspaper and towel.
(b) newspaper, towel, dry marble floor, wet marble floor.
(c) towel, newspaper, dry marble floor, wet marble floor
(d) wet marble floor, dry marble floor, towel, newspaper
► (a) wet marble floor, dry marble floor, newspaper and towel.

4. Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

Frictional force is acting opposite to the movement of the book i.e. upwards.

5. You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?

It would make it more difficult for us to walk on a soapy floor because layer of soap makes floor smooth. The coating of soapy water reduces the friction and the foot can not make a proper grip on the floor and it starts getting to slip on the floor.

6. Explain why sportsmen use shoes with spikes.

Sportsman use shoes with spike to increase the friction so that the shoes do not slip while they run or play.

7. Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

Seema will have to apply larger force since she will experience more frictional force because heavy object will be pressed hard against the opposite surface and produces more friction.

8. Explain why sliding friction is less than static friction.

Sliding friction is always less than static friction because two sliding objects find less time to get interlocked against each other’s irregularities of surfaces as a result of which they experience less friction.

9. Give examples to show that friction is both a friend and a foe.

Friction as friend:
→ We are able to walk because of friction.
→ Friction between the tip of the pen and a paper allows us to write.
Friction as foe:
→ Tyres and soles of shoes wear out because of friction.
→ Friction between the different parts of machines produces heat. This can damage the machines.

10. Explain why objects moving in fluids must have special shapes.

When a body moves through a fluid, it experiences an opposing force which tries to oppose its motion through the fluid. This opposing force is known as the drag force. This frictional force depends on the shape of the body. By giving objects a special shape, the force of friction acting on it can be minimised. Hence, it becomes easier for the body to move through the fluid.

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## Chapter 12 Friction Class 8 Science NCERT Solutions

NCERT Solutions is an effective method for learning since you can learn a lot within a short time. These are helpful in building a great foundation of concepts and make easy for the students to understand basics. You will develop the ability to identify what improvements and changes need to be made.

### Class 8 Science Chapter 12 Friction NCERT Questions and Answers - Topics

• Force of Friction
• Factors affecting Friction
• Friction: A Necessary Evil
• Increasing and Reducing Friction
• Wheels Reduce Friction
• Fluid Friction

### Chapter 12 Friction NCERT Solutions for Class 8 Science  - Notes

• Friction is a force that opposes the relative motion between two surfaces of objects in contact. The force of friction always acts in a direction opposite to that of the applied force.

• Friction is caused by the irregularities on the two surfaces in contact. On rough surfaces, there are a larger number of irregularities. So the force of friction is greater if a rough surface is involved.

• If an object started moving, it would never stop if there were no friction. On the other hand, friction is an evil, too. It wears out the materials whether they are screws, ball bearings or soles of shoes/

• Sliding friction between the moving parts of vehicles can be reduced by using oil, grease or graphite.

• In electrical plugs, graphite is used to reduce friction between the plug pins and the corresponding socket.

• The interlocking of irregularities on the surfaces of two bodies in contact, which cause friction is overcome to great extent by the use of lubricants.

• When one body rolls over the surface of another body, the resistance to its motion is called rolling friction. Rolling reduces friction.

• Sliding friction is friction that acts on objects when they are sliding over a surface. Common examples are the use of ball bearings between hubs and the axles of ceiling fans and bicycles.

• The force exerted by fluids on objects in motion through them is called fluid friction. The frictional force exerted by fluids is also called drag.

### Chapter 12 Friction Class 8 Science Questions and Answers - MCQ Questions with answers

1. Friction produces:
a) Motion
b) Force
c) Heat
d) Light
► c) Heat

2. Friction always
a) helps the motion
b) opposes the motion
c) both of the above
d) none of the above
► b) opposes the motion

3. It is easier to hold a earthen pot than steel pot as
a) Earthen pot has less friction
b) Steel pot is comparatively heavier
c) Earthen pot has more friction
d) Steel pot has more friction
► c) Earthen pot has more friction

4. Why does a meteor burn upon entering the earth's atmosphere?
a) Due to gravitational pull
b) Due to the heat of the earth
d) Due to excess friction in air
► d) Due to excess friction in air

5. In machine, friction between moving parts is reduced by:
a) Heating machine
b) Using powder
c) Using lubricants
d) Using paints
► c) Using lubricants

6. Substances are called lubricants which are used to
a) increase friction
b) decrease friction
c) increase or decrease friction
d) none of the above
► b) decrease friction

7. Why are the head of a match stick and the sides of a match box deliberately made rough?
a) To increase friction
b) To decrease friction
c) To increase the amount of heat
d) To decrease the amount of heat
► a) To increase friction

8. The frictional force exerted by fluids is also called
a) Drag
b) Rung
c) Smug
d) Slag
► a) Drag

9. Which of the following is a contact force?
a) Magnetic forces
b) Electrostatic force
c) Gravitational force
d) Friction
► d) Friction

10. What will happen to a moving object if there is no friction?
a) The object will stop.
b) The object will keep on moving.
c) The object will change speed.
d) The object will change direction.
► b) The object will keep on moving.

NCERT Solutions for Science prepared by our experts try to provide all round clarity of questions. Students should also refer previous year questions and practise test papers and worksheets to assess their key areas. Class 8 NCERT Solutions is an effective method for learning since you can be le to learn a lot within a short time.