This document contains a lesson plan about friction for an 8th grade science class. It includes objectives, an introduction to friction, factors that affect friction like surface roughness and pressure, the different types of friction, examples of when friction is useful and undesirable. It also discusses how to increase and decrease friction and introduces the concept of fluid friction.

1. DELHI TEACHERS’ TRAINING
COLLEGE
DEENPUR, NAJAFGARH, NEW DELHI – 110043
(Affiliated to G.G.S.I.P. University, Delhi – 110075)
B.Ed. 2015 – 2017
Semester - III
Submitted By:-
Swati Ghansela
Enrollment No.-
05940202115

2. Made By – Swati Ghansela
MULTIMEDIAMULTIMEDIA
LESSON PLANLESSON PLAN
(FRICTION)(FRICTION)

3. General Objectives:-
i) To enable the students to understand the concept of Science
ii) To develop the logic and reasoning power of the students
iii) To arouse the interest of the students in the quantitative side of the world
Specific Objectives :-
1.Cognitive domain
(a) Knowledge level
The students will be able to
i. define friction
ii. list the types of friction
(b) Understanding level
The students will be able to
i. explain the effect of friction
identify the state of object after application of friction
Name of the School: BVM Public School
Class: 8th
Subject: Science
Lesson Plan
Topic: Friction

4. (c) Application level
The students will be able to illustrate the effects of friction with example
(2) Affective Domain
The students will be able to acknowledge and associate the learning with real life.
(3) Psychomotor Domain
The students will be able to write the conditions when friction is useful and unuseful
Statement of Aim:-
Today we are going to study the concept of friction
Teaching Aid:-
 Power point presentation
Previous Knowledge:-
 Students are aware of force
Recapitulation:-
 Formula of Area of cube, cuboid
 Volume of cube ,cuboid
Homework:-
 Solve 5 questions each related to area, perimeter from your textbook.

5. FORCE OF FRICTION
 Force of friction is the force which opposes the motion of an object over a surface.
 The force of friction acts between the object and the surface.
 Friction is caused by the irregularities on the two surfaces in contact.
 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.
Example :- A ball rolling on ground gradually slows down and comes to
rest due to force of friction between the ball and the ground.
If we stop pedaling a bicycle, it gradually slows down and comes to a stop due to force
of friction between the wheel and the road.
INTRODUCTION

6. Introducing Friction

7. FACTORS AFFECTING
FRICTION
Friction depends upon two factors. They are :-
i) Nature of the surfaces in contact. ( The smoothness of the surfaces).
ii) How hard the surfaces press together.
Friction is less on a smooth surface.
.

8. Friction is more on a rough surface.
On rough surfaces, there are a larger number of
irregularities. So the force of friction is greater if
a rough surface is involved.
Activity:-
1.Place a book on table.
2.Push a book on table.
Observation:-
After sliding few distance the book stopped.
Result :- Friction opposes relative motion between the
surfaces of the book and the table

9. Friction is more if the surfaces are
pressed harder…………….?
Friction is less if the surfaces are
not pressed harder…………..?

10. CAUSE OF FRICTION
Friction is caused due to the interlocking of irregularities between the
two surfaces in contact.
Smooth surfaces have minute irregularities between the two surfaces.
Rough surfaces have larger irregularities between the two surfaces.
So force of friction is more if the surfaces are rough.

11. TYPES OF FRICTION
There are three main types of friction. They are static friction, sliding friction and rolling
friction.
a) Static friction is the friction exerted on a object at rest. .
b) Sliding friction is the friction exerted when an object slides over a
surface.
c) Rolling friction is the friction exerted when an object rolls over a
surface.
Sliding friction is slightly less than static friction.
Rolling friction is less than sliding friction and static friction.

12. Static friction Sliding friction
Rolling friction

13. FRICTION IS
SOMETIMES USEFUL
Friction is useful for many of our daily activities.
 Friction between the feet and ground helps us to walk on the ground.
 It is possible to write with a pen or pencil on a paper due to friction between
the pen or pencil and the paper.
 It is possible to write on a blackboard due to the friction between the chalk and black
board.
 Friction between the tyres and the road helps automobiles to move on roads.
 Friction between the bricks helps in the construction of buildings.

14. For holding a glass
For walking To write on board
For construction
Friction Between
Pen & Paper For driving

15. FRICTION IS SOMETIMES
UNDESIRABLE
 Soles of shoes wear out due to friction.
 Tyres of bicycles and automobiles wear out due to friction.
 Steps of staircases and foot over bridges in railway stations wear out due to friction.
 Knives and razors lose their sharp edges due to friction.

16. INCREASING FRICTION
Friction can be increased by increasing the roughness of the surfaces in contact.
Eg :-
1.The soles of shoes are grooved to have a better grip on the floor.
2.The tyres of vehicles are treaded to increase the grip on the road.
3.The break pads of vehicles are rough to stop moving vehicles when the breaks are applied.
4.Gymnasts apply some coarse substance on their hands for a better grip.

17. REDUCING FRICTION
FRICTION CAN BE REDUCED BY :-
 Using lubricants like powders or oils and grease.
 Using rollers or wheels.
 Using ball bearings.
 We sprinkle powder on a carrom board to reduce friction.
 Oil or grease is applied between moving parts of machines to reduce friction.
 Rollers are used in luggage bags to reduce friction.
 Wheels are used in vehicles to reduce friction.
 Ball bearings are used in ceiling fans, bicycles and vehicles to reduce friction.

18. FLUID FRICTION
Fluid friction is the force of friction exerted by liquids and gases on objects moving through
them.
Fluid friction depends upon :-
1.The speed of the object.
2.Shape of the object.
3.The nature of the fluid.
Example:-
Birds flying in air have streamlined body to reduce fluid friction.
Fishes living in water have streamlined body to reduce fluid friction.
Aeroplanes and spacecraft have streamlined body to reduce fluid friction.