NCERT Class 8 Science Friction

Read and download NCERT Class 8 Science Friction in NCERT book for Class 8 Science. You can download latest NCERT eBooks chapter wise in PDF format free from Studiestoday.com. This Science textbook for Class 8 is designed by NCERT and is very useful for students. Please also refer to the NCERT solutions for Class 8 Science to understand the answers of the exercise questions given at the end of this chapter

NCERT Book for Class 8 Science Chapter 12 Friction

Class 8 Science students should refer to the following NCERT Book Chapter 12 Friction in Class 8. This NCERT Book for Class 8 Science will be very useful for exams and help you to score good marks

Chapter 12 Friction NCERT Book Class 8

 

FRIICTIION

You might have seen a driver of a car or a truck slowing down the vehicle at a traffic signal. You, too, slow down your bicycle whenever needed by applying brakes. Have you ever thought why a vehicle slows down when brakes are applied? Not only vehicles, any object, moving over the surface of another object slows down when no external force is applied on it. Finally it stops. Hav you not seen a moving ball on the ground stopping after some time? Why do we slip when we step on a banana peel (Fig. 12.1)? Why is it difficult to walk on a smooth and wet floor? You saw that if you apply the force along the left, friction acts along the right. If you apply the force along the right, the friction acts along the left direction. In both cases the force opposes the motion of the book. The force of friction always opposes the applied force. In the above activity, the force of friction acts between the surface of the book and the surface of the table. Is the friction the same for all the surfaces? Does it depend on the smoothness of the surfaces? Let us find out.

12.2 Factors affecting

FrictionDoes the distance covered depend on the nature of the surface on which the cell moves? Could the smoothness of the surface of the cell also affect the distance travelled by it? Friction is caused by the irregularities on the two surfaces in contact. Even those surfaces which appear very smooth have a large number of minute irregularities on them (Fig. 12.5). Irregularities on the two surfaces lock into one another. When we attempt to move any surface, we have to apply a force to overcome interlocking. On rough surfaces, there are a larger number of irregularities. So the force of friction is greater if a rough surface is involved.

We see that the friction is caused by the interlocking of irregularities in the two surfaces. It is obvious that the force of friction will increase if the two surfaces are pressed harder. You can experience it by dragging a mat when nobody is sitting on it, and when a preson is sitting on it.

Recall your experience when last time you moved a heavy box from one place to another. If you have no such experience, get that experience now. What is easier — to move the box from rest, or to move it when it is already in motion? The force required to overcome friction at the instant an object starts moving from rest is a measure of static friction. On the other hand, the force required to keep the object moving with the same speed is a measure of sliding friction. friction and you find it somewhat easier to move the box already in motion than to get it started.

12.3 Friction : A Necessary Evil

Recall now some of your experiences. Is it easier to hold a kulhar (earthen pot) or a glass tumbler? Suppose the outer surface of the tumbler is greasy, or has a film of cooking oil on it; would it become easier or more difficult to hold it? Just think : would it be possible to hold the glass at all if there is no friction?

Recall also how difficult it is to move on a wet muddy track, or wet marble floor. Can you imagine being able to walk at all if there were no friction? When the box starts sliding, the contact points on its surface, do not get enough time to lock into the contact points on the floor. So, the sliding friction is slightly smaller than the staticYou could not write with pen or pencil if there were no friction. When your teacher is writing with chalk on the blackboard, its rough surface rubs off some chalk particles which stick tothe black board. Could it happen if there were no friction between the chalk and the board?

If an object started moving, it would never stop if there were no friction. Had there been no friction between the tyres of the automobiles and the road, they could not be started or stoped or turned to change the direction of motion. You could not fix a nail in the wall (Fig. 12.7) or tie a knot. Without friction no building could be constructed.

Exercises

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.

2. Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing 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

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 order will 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

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.

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

6. Explain why sportsmen use shoes with spikes.

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?

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

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

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


Please refer to attached file for NCERT Class 8 Science Friction

Chapter 01 Crop Production and Management
NCERT Class 8 Science Crop Production And Management
Chapter 02 Microorganisms: Friend or Foe
NCERT Class 8 Science Microorganisms Friend And Foe
Chapter 03 Synthetic Fibres and Plastics
NCERT Class 8 Science Synthetic Fibres And Plastics
Chapter 04 Materials Metals and Non-Metals
NCERT Class 8 Science Materials Metals And Non Metals
Chapter 05 Coal and Petroleum
NCERT Class 8 Science Coal And Petroleum
Chapter 06 Combustion and Flame
NCERT Class 8 Science Combustion And Flame
Chapter 07 Conservation of Plants and Animals
NCERT Class 8 Science Conservation Of Plants And Animals
Chapter 08 Cell Structure and Functions
NCERT Class 8 Science Cell Structure And Functions
Chapter 09 Reproduction in Animals
NCERT Class 8 Science Reproduction In Animals
Chapter 10 Reaching the Age of Adolescence
NCERT Class 8 Science Reaching The Age Of Adolescence
Chapter 11 Force and Pressure
NCERT Class 8 Science Force And Pressure
Chapter 12 Friction
NCERT Class 8 Science Friction
Chapter 14 Chemical Effects of Electric Current
NCERT Class 8 Science Chemical Effects Of Electric Current
Chapter 15 Some Natural Phenomena
NCERT Class 8 Science Some Natural Phenomena
Chapter 17 Stars and the Solar System
NCERT Class 8 Science Stars And The Solar System
Chapter 18 Pollution of Air and Water
NCERT Class 8 Science Pollution Of Air And Water
Other Topics Class 8 Science
CBSE Class 8 Science Activity A Forseful Story
CBSE Class 8 Science Activity A Friend Indeed
CBSE Class 8 Science Activity A Mouldy Party
CBSE Class 8 Science Activity A Surprising Fact
CBSE Class 8 Science Activity A Tree Study
CBSE Class 8 Science Activity Back to the Earth
CBSE Class 8 Science Activity Bring Back The Shine
CBSE Class 8 Science Activity Delightful Daydreams
CBSE Class 8 Science Activity Egg Pops Into a Bottle
CBSE Class 8 Science Activity Growing Up
CBSE Class 8 Science Activity How Does Sound Travel
CBSE Class 8 Science Activity I Can See it
CBSE Class 8 Science Activity I Can See My Sound
CBSE Class 8 Science Activity Inside Story
CBSE Class 8 Science Activity Interview
CBSE Class 8 Science Activity Is The Moon Growing
CBSE Class 8 Science Activity Its CO2 Again
CBSE Class 8 Science Activity Just for Fun
CBSE Class 8 Science Activity Lets Make Music
CBSE Class 8 Science Activity Lighter or Heavier
CBSE Class 8 Science Activity Make A Periscope
CBSE Class 8 Science Activity Make Your Little Movie
CBSE Class 8 Science Activity Making a Solar System Model
CBSE Class 8 Science Activity Mysterious Forces
CBSE Class 8 Science Activity Pitcher Power
CBSE Class 8 Science Activity Please Hear
CBSE Class 8 Science Activity Spore Magic
CBSE Class 8 Science Activity Stages of Human Reproduction
CBSE Class 8 Science Activity Story of Granny
CBSE Class 8 Science Activity Suno Suno
CBSE Class 8 Science Activity The Ball Bearing
CBSE Class 8 Science Activity The Puzzling Letters
CBSE Class 8 Science Activity The Story of Magdeberg Hemisphere
CBSE Class 8 Science Activity The Tug of War
CBSE Class 8 Science Activity Want to be a Snake Charmer
CBSE Class 8 Science Activity What Makes Water
CBSE Class 8 Science Activity Wndow to our Rish BioDiversity
CBSE Class 8 Science Poster Making

Science NCERT Book Class 8 Chapter 12 Friction

The above NCERT Books for Class 8 Science Chapter 12 Friction have been published by NCERT for latest academic session. The textbook by NCERT for Chapter 12 Friction Science Class 8 is being used by various schools and almost all education boards in India. Teachers have always recommended students to refer to Chapter 12 Friction NCERT etextbooks as the exams for Class 8 Science are always asked as per the syllabus defined in these ebooks. These Class 8 Chapter 12 Friction book for Science also includes collection of question. We have also provided NCERT solutions for Class 8 Science which have been developed by teachers of StudiesToday.com after thorough review of the latest book and based on pattern of questions in upcoming exams for Class 8 students.

NCERT Book Class 8 Science Chapter 12 Friction

The latest NCERT book for Chapter 12 Friction pdf have been published by NCERT based on the latest research done for each topic which has to be taught to students in all classes. The books for Class 8 Science Chapter 12 Friction are designed to enhance the overall understanding of students. All Class 8 NCERT textbooks have been written in an easy to understand language which will help to enhance the overall level of Class 8 students. 

Chapter 12 Friction NCERT Book Class 8 Science

As the students of Class 8 need the books for their regular studies, we have provided all NCERT book for Chapter 12 Friction in pdf here for free download. All pdf NCERT books available here for Class 8 will help them to read on their mobile or computers. They can take a print of the Class 8 Science NCERT Book Chapter 12 Friction pdf easily and use them for studies. The NCERT textbooks for Class 8 Science have been provided chapter-wise and can be downloaded for free of cost. 

Class 8 Science Chapter 12 Friction NCERT Book

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Class 8 Chapter 12 Friction NCERT Book Science

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