curriculum development panel

Curriculum Development Panel

Class: VIII Subject: Physics Developed by: Department of Curriculum Planning & Development

Reviewed by: Internal Review Department

Army Public Schools and Colleges System Second Term Warm Region 2021-2022

Round 3: 25 October 2021 – 21 January 2022 Class: VIII Subject: Physics

Index Page

Content of Syllabus Contents of the Pack Time Allocation Prescribed Textbooks: Physics 9, Caravan Book House, Lahore

Notebooks Prescribed: Single Line Notebook (Large)/Register Topics for 2nd Term Round 3: · Unit 3 Dynamics (pgs 55-76 &

81-83)

Cover Page: 01

Curriculum Panel: 01

Index page: 01

Block Syllabus: i

Syllabus Break-up: 17

Note: It is the responsibility of Section Head

to ensure the availability of Syllabus Implementation Guide for Teachers

Booklet to the teachers, so that the

instructions given in the Syllabus

Break-ups are implemented

effectively.

· Revision / Completion Weeks 04

· Teaching Weeks: 08

· Total No. of Periods: 8 x 4 = 32

Winter Break: 25 Dec 2021 - 02 Jan 2022

Subject: Physics Second Term (2021-2022) Class: VIII

i

Block Syllabus for Round 3

Distribution of Topics within Teaching Periods Note: · Progression of teaching will be done as indicated topically in the block below. In order to implement teaching effectively, teachers must read

Syllabus Break-up, Syllabus Implementation Guide and Curriculum Mapping document in depth.

· The complete BLOCK must be read by teachers to plan daily lessons and Check Points properly.

· The topics for revision periods must be planned during the coordination meeting and detailed plan be written in teacher’s planner.

· Significant concepts/topics for teaching have been identified for each chapter/unit. No. of

Periods Unit No. Topics Questions & Problems Practicals

32 Periods *

Unit 3 Dynamics

3.1 Force, Inertia and Momentum 3.2 Newton’s Laws of Motion

· Tension And acceleration in a String · Force and Momentum · Law of Conservation of Momentum

3.3 Friction Significant topics taught in this chapter are: · Force, inertia and momentum · Newton’s 1st Law of motion · Newton’s 2nd Law of motion Ø Mass and Weight

· Newton’s 3rd Law of motion Ø Tension And acceleration in a String Ø Force and Momentum Ø Law of Conservation of Momentum

· Friction Ø Coefficient of Friction

Questions3.1-3.19 Problems 3.1-3.9

Practical 3 · To find the acceleration

of a ball rolling down an angle iron by drawing a graph between 2S and T2.

Practical 4 · Investigate the relation

between force of limiting friction and normal reaction to find the coefficient of sliding friction between a wooden block and a horizontal surface.

Second Term (2021-2022)

Subject: Physics-VIII No. of Periods Per Week: 4

Restricted Page 1 of 17

APSACS Syllabus Breakup Second Term Warm Region 2021-2022

Round 3: 25 October 2021 – 21 January 2022

Topic Objectives /Learning Outcomes

Teaching Methodology Activities Resources

Unit 3 Dynamics 3.1 FORCE INERTIA

AND MOMENTUM

· FORCE · INERTIA · EXPERIMENT

3.1 · MOMENTUM

Students will be able to: · define

dynamics, force, inertia and momentum and relate these concepts to daily life

· solve numerical problems related to the momentum

Dynamics: pg 57 · Recap kinematics. · Introduce the branch of mechanics known as dynamics.

Give examples from daily life to highlight the difference between kinematics and dynamics.

Force: pgs 57, 58 · Ask the students: What is/are the term (s) you associate

with actions such as push, pull, twist, and squash? Define force and explain its effects.

Historical introduction: · For centuries and millennia scientists continue to ponder

over objects, their motion and the factors which cause motion. Galileo played a key role in this field of Physics and Newton revolutionized the study of motion by introducing the laws of motion.

Inertia: pg 58 · Ask the students to state their observation when teacher

(or teacher gives any of the students a chance to demonstrate) pushes first the duster placed on the table and then the table gently with the same force and later pushes the table with greater force. Now ask the students to analyze their observations i.e. why didn’t the table move when it was pushed gently? Is there any specific physical quantity which has different values for the table and the duster and by virtue of which the table maintained its state and the duster couldn’t? Which one

· Evaluate students’ level of understanding and their application and analytical skills by asking MCQs, short questions/ answers related to the inertia, momentum and first law of motion

C.W. · Short

questions/answers based on dynamics and force.

· Numerical problems based on the

· Physics (IX) Caravan Book House, Lahore pgs 55-59, 82

· Marker, Board, Marker

· Available A/V Aids

Conceptual linkage This unit is built on Forces & Motion Science IV & Forces and their effects Science VII This unit leads






is difficult to stop? A car or a bicycle, given that both move with the same speed.

· Explain that inertia is that characteristic of a body due to which it resists any change in its state of rest or motion.

· Perform experiment 3.1. Momentum: pg 59 · Recap previous knowledge by asking the same question

as asked while teaching inertia: Which one is difficult to stop, a car or a bicycle, given that both move with the same speed?

· After getting the feedback ask the students: Which one is difficult to stop? A bicycle moving with 3ms−1 (slow) and the same bicycle (equal in mass) moving with 15ms−1 (fast). Is it difficult to stop a fast moving ball or a slow moving ball (of equal mass as the fast one)? Is it difficult for them to stop a bullet, a bulldozer or a lorry? Why? Which feature (associated physical quantity) of a bullet makes it difficult to stop and which feature (associated physical quantity) of a bulldozer or a lorry makes it difficult to stop (or move when at rest)? Can you imagine a lorry moving with the velocity of a bullet? It means, motion of objects depends upon mass as well as velocity i.e. mass and velocity affect the quantity of motion of a body. This quantity of motion is termed as momentum and is denoted by P. Since momentum depends upon both mass and velocity, therefore it is defined as the product of mass and velocity i.e. P = mv

· Since students are familiar with the SI unit of mass and velocity, let them try to find out the SI unit of momentum. Teacher to provide guidance wherever necessary.

concept of momentum.

H.W. · Ask students

to gather information about Newton and submit the research online.






· Design at least two numerical problems related to momentum and let the students solve them.

Note: Discuss & explain all the side information boxes in the Textbook whenever the relevant concept is being developed.

Unit 3 Dynamics 3.2 NEWTON’S

LAWS OF MOTION

· NEWTON’S FIRST LAW OF MOTION

· NEWTON’S SECOND LAW OF MOTION

· UNIT OF FORCE · MASS AND

WEIGHT · NEWTON’S

THIRD LAW OF MOTION

Students will be able to: · state and

explain Newton’s laws of motion

· described the concept of force, represent it quantitatively and derive unit of force

· solve numerical problems related to Newton’s laws of motion

· identify the principle of dynamics with reference to the motion of

First Law of Motion: pgs 59, 60 · Recap Inertia. · Ask the students: Will the state of rest of a glass placed

on the table change when there is no force applied on it? Can the glass be made to move by pushing it? What will happen to the motion of a moving car when its engine is turned off? Will it stop instantly or stop after covering some distance? What agent causes the car to stop?

· Explain the first law of motion with examples from daily life and relate it with the concept of inertia. Following graphic organizer can be useful in explaining first law of motion stepwise.

C.W. · MCQs & Short

questions/ answers based on the second law of motion example 4.2 pg 61 Textbook

· Problems 3.1 and 3.4 pg 83 Textbook

· Physics

(IX) Caravan Book House, Lahore pgs 59-64, 82 & 83

· Marker, Board







human beings, objects, and vehicles (e.g. analyse the throwing of a ball, swimming, boating and rocket motion)

· distinguish between the mass and weight

· solve numerical problems using F=ma and w=mg

· If possible let the students watch the explanation of first law on a multimedia or at least on a laptop with proper sound from the website https://www.youtube.com/watch?v=Kx2yqEB20k8

· Ask students to visit https://www.grc.nasa.gov/www/k-12/airplane/newton1g.html to explore more examples of Newton’s First law of motion and submit them online.

Newton’s Second Law of Motion: pgs 60-62 · Recap the previous knowledge about acceleration and

the relation of mass with inertia of a body. · Ask the students: When will the tennis ball undergo

greater change in velocity, if hit gently with a small force or hit hard with greater force?

· Explain that magnitude of change in velocity or amount of acceleration produced in a body is directly related to the magnitude (little and greater) of applied force, the greater the force applied on the body, the greater the amount of acceleration produced in it and vice versa. Introduce the relation: a Fµ ……1

· Ask the students: Which ball will move faster or undergo greater change in velocity, if hit with the same force, a tennis ball or a football?

· Explain that magnitude of change in velocity or amount of acceleration produced in a body is directly related to the quantity of mass (lighter and heavier) of a body.

Introduce the relation: 1am

µ ……2

· After getting feedback from students as how to combine the two relations: aµ F/m Þ a = k F/m and for k=1, the above equation will be a = F/m

· Ask the students to explain the equation and then state

· Teacher to ask

the ‘Quick Quiz’ on page 64 Textbook

https://www.youtube.com/watch?v=Kx2yqEB20k8

https://www.grc.nasa.gov/www/k






Newton’s second law of motion. Rearrange the equation: Þ F = ma

· Ask the students: Is there any acceleration produced when you push the wall of the classroom?

· Unit of Force: pg 60 As students are aware of the units of mass and acceleration, let them derive the unit of force using the equation: F=ma

· Define one Newton as the force that produces an acceleration of 1ms−2 in a body of mass of 1kg. Ask students to define one Newton using values of mass and acceleration other than 1kg and 1ms−2 i.e. what force is needed to produce an acceleration of 10ms−2 in a body of mass 0.1 kg?

· Teacher to solve examples 3.1 and 3.3 on pages 61, 62 of the Textbook.

· Let the students to solve Example 3.2 on page 61 and problems 3.1 and 3.4 on page 83 of the Textbook.

Mass and Weight: pgs 62, 63 · Recap the definition of mass. · Ask the students: what is their weight? Some students’

answers might be in kilograms. Ask the same students: Is there any difference between mass and weight? Isn’t weight a force (book placed)? Do kilograms and Newton represent the same physical quantities? Do they remember any equation which relates mass and force?

· Explain second law of motion i.e. mass is the characteristic of a body which determines the acceleration produced when a certain force acts on the body. Mass is a scalar quantity and a simple balance is used to measure it. Weight is the force exerted by the

C.W. · Short

questions/ answers based on mass and weight and the third law of motion

· Problems 3.2, 3.3and 3.5 pg 83 Textbook






earth on an object towards its centre and by the second law it is w = mg; g is the acceleration of free falling bodies due to gravity. Weight of the object is measured by a spring balance.

· If possible let the students watch the explanation of second law on a multimedia or at least on a laptop with proper sound from the website https://www.youtube.com/watch?v=AFwbcWIUwLQ

· Ask the students to solve the numerical problems. 1. What is the mass of a duster placed on the rostrum if

the reaction force on the duster is 3N? 2. Problems 3.2 and 3.5 on page 83 of the Textbook.

Third Law of Motion: pgs 63, 64 · Recap previous knowledge relating acceleration

produced in a body as a result of applied force on the body.

· Ask students to find the common sequence of events in the following examples while the teacher narrates them. · When a rubber ball hits (teacher to show the

direction) the ground it bounces back (teacher to emphasize the word back and show the direction physically not verbally).

· When a bullet is fired from the gun, as soon as the bullet moves forward, out of the barrel, the gun moves backward pushing the person holding the gun.

· When a swimmer pushes the jumping pad down he is thrown up into the air.

· After getting feedback from the students, teacher to introduce the third law of motion and give students some time to reflect on their observations and again relate the

H.W. Ask students to find examples describing Newton’s third law, other than those discussed in the class and submit the work as an online assignment

https://www.youtube.com/watch?v=AFwbcWIUwLQ






events with the third law, this time, preferably in groups. Ask each group if they can think of more examples involving action and reaction events.

· When each group gives its feedback, teacher to quote the examples of walking and a book placed on the table. Since it is easier for students to identify action and reaction when there is motion of object (s) in opposite directions (bullet and gun, up and down motion of a ball, pad and swimmer and ground and feet) as a result of action and reaction, but there is no motion happening in the case of book and table. Book is at rest because two equal and opposite forces act on it. Action is the weight of the book on the table acting in the downward direction and as a reaction the table exerts reaction on the book in the upward direction.

· Ask the ‘Quick Quiz’ on page 64 Textbook. Let the students solve problem 3.3 on page 83 of the Textbook.


LAWS OF MOTION CONTD…

TENSION AND ACCELERATION IN A STRING I. VERTICAL

MOTION OF

Students will be able to: · describe how

the tension in a string is related to the weight of an object attached to the string

· calculate

Tension and acceleration in a string: pg 64 · Recap the previous lesson by asking the students to

identify action and reaction by holding an object in your hand with your palm open.

· After getting the feedback, ask the students to identify the action and reaction by suspending an object by a string while holding the string in your hand and in case of the chandelier or fan suspended by a rod from the ceiling. Students will easily identify weight of the object but might find it difficult to identify the other force i.e. tension. Introduce tension as a force and cite some examples. Draw the figure 3.11 and explain action and reaction and the direction of tension at both ends of the

· Evaluate

students’ level of understanding and their

· Caravan

Book House, Lahore pgs 64-67, 83

· Marker, Board, Weights, Pulley, String, Stand and






TWO BODIES II. WHEN ONE

BODY MOVES VERTICALLY AND THE OTHER HORIZONTALLY ON A SMOOTH SURFACE

tension and acceleration in a string during motion of bodies connected by the string and passing over frictionless pulley using second law of motion

· solve numerical problems related to the tension in the string and acceleration of the object attached to the string

string. The magnitude of tension throughout the string is uniform. Explain the relation: T= w

Motion of bodies connected by a string I. When the bodies move vertically: pgs 64-66 · Recap the previous lesson by recalling the example of

an object suspended by the string. There are two forces acting on the object but the object is still not moving. Ask the students: why is it so? What is the net force? Is it possible for a body to acquire acceleration without any net force being applied on it?

· If possible demonstrate the setup of fig 3.12 in the class. Otherwise draw the figure on the board i.e. two objects A and B of masses m1 and m2, respectively suspended by two ends of an inextensible string which passes over a frictionless pulley such that m1 > m2. m1 being heavier of the two masses will move downwards, while m2 will move upwards. To find the values of acceleration ‘a’ of two bodies and tension ‘T’ in the string, analyze the motion of A and B with the help of students. The possible questions are: What are the forces acting on object A? In which direction do they act? Is there any net force (Do tension and weight cancel each other’s effect)? If no, ask: then how does object A move? And if yes, then is there any relation between the acceleration of the object A and the direction and magnitude of the net force?

· Write Net Force = m1a also Net Force= Difference of weight of A (downward force) and tension in the string (upward force). From the two equations m1a = m1g-T….1 For the motion of body B, a similar relation can be

application and analytical skills while they solve problems related to tension in the string.

C.W. · Example 3.4

pg 65 Textbook

· Problem 3.6 pg 83 Textbook

available A/V Aids






derived by asking the students similar questions m2a =T-m2g….2 · Ask the students to find out the following relations

1 2

1 2

m ma gm m

-=

+ & 1 2

1 2

2m mT gm m

=+

by simultaneously solving equations1 and 2. (Students have done linear simultaneous equations algebraically and graphically in New Maths Syllabus II). Assess the class while they are doing it. Give constructive feedback and on-spot guidance (to whomsoever necessary). If any student finishes it earlier than the others, then ask him to do it on the board.

· Teacher to solve example 3.4 Pg 65 of the Textbook on the board.

· Students to solve problem 3.6 on pg 83 of the Textbook. II. When one body moves vertically and the other horizontally: pgs 66, 67 · Recap the previous lesson by recalling the example of

object (s) suspended by a string. · If possible demonstrate the setup of fig 3.13 in the class.

Otherwise draw the figure on the board i.e. two objects A and B of masses m1 and m2 respectively suspended by two ends of an inextensible string which passes over a frictionless pulley such that m1 > m2. The body A moves vertically downwards whiles the body B moves on the frictionless horizontal surface. To find the values of acceleration ‘a’ of two bodies and tension ‘T’ in the string, analyze the motion of A and B with the help of students. The possible questions are: What are the forces acting on object B? In which direction do they act? Since the body moves in a horizontal direction only,

C.W. · Example 3.5

pg 67 Textbook

· Problem 3.7 pg 83 Textbook






what does it tell about the net force in horizontal and vertical directions?

· Write For body of mass m2 In vertical direction Net Force = 0 Þ m2g-R = 0 Þ m2g=R In horizontal direction Net Force = m2a = T ….1

· Students are now familiar with the vertical motion of a body suspended by a string, passing over a frictionless pulley. So instead of following the previous procedure, ask students to find equation of motion for the motion of a body moving vertically themselves. Providing feedback/guidance (to whomsoever necessary). m1a = m1g-T ….2 Again, students will be asked to solve equation 1 and 2 to find

1

1 2

ma gm m

=+

&

1 2

1 2

m mT gm m

=+

.

· Check whether the Struggling Learners of previous week have improved with your feedback or not.

· Teacher to solve example 3.5 on pg 67 of the Textbook on the board.

· Students to solve problem 3.7 on pg 83 of the Textbook. Revision: · Revision of concepts learned. · Students to practice numerical problems.







LAWS OF MOTION CONTD…

· FORCE AND

MOMENTUM · LAW OF

CONSERVATION OF MOMENTUM

Practical 3 · To find the

acceleration of a ball rolling down an angle iron by drawing a graph between 2S and T2.

Students will be able to:

· define the

terms system and isolated system

· analyze the relation between force and momentum

· identify the safety devices (such as packaging of fragile objects, the action of crumple zones and seatbelts) utilized to reduce the effects of changing momentum

· state the law of conservation of momentum and determine the velocity after collision

· Recap momentum.

Force and Momentum pgs 67-69 · Recap the previous lesson by asking the question, what

is the unit of momentum? Introduce unit of momentum Ns where N is unit of force and s is unit of time. Ask students to compare it with the unit of momentum studied earlier. Ask the students: What do the units signify? A relation of momentum with force and time. Now explain, that in order to relate they need to consider an object of mass m initially moving with velocity vi and suppose a force F is applied on the object. Will the force have an impact on the motion of the object? How? Since mass of the object is same then which quantity undergoes change? Explain that velocity will change to vf from vi

· Change in momentum = Final momentum minus initial momentum= mvf – mvi

· Þ Change in momentum = mvf – mvi = Pf – Pi · Ask the students, what is the amount of time in which

this change is brought about? Tell the students to suppose that two persons are driving their cars on the same road at the same speed. There is a speed-breaker at a certain point on their way and one person notices it from a long distance and the other one notices it when his car is very near the point. Who will be safer and why? The first person had more time to change the momentum of his car, while the second one had very little time and hence rate of change of momentum is equal to change in momentum divided by time elapsed for the change to take place i.e. Rate of change of

C.W. · Example 3.6

pgs 68, 69 of the Textbook and problem 3.8 on pg 83.

· Evaluate students’ understanding of law of conservation of momentum by asking short questions

· Physics


· Practical Notebook (9th & 10th)

· Marker, Board,







of two bodies and relate with daily life examples

· solve numerical problems related to the concepts learned

· find the acceleration of a ball rolling down an angle iron by drawing a graph between 2S and T2.

momentum is given by f i f i

f i f i

P - P mv - mv t t

P - P m(v - v ) t t

=

Þ =

When asked, students easily identify that the quantity f i(v - v )t

is the amount of acceleration produced.

Rate of change of momentum = ma When asked, students may easily identify the quantity ma and the 2nd law of motion from which it comes i.e. F = ma

· Ask the students: How did the two persons change the momentum of their cars? By applying braking force? Rate of change of momentum = F Rate of change of momentum of a body is equal to the applied force on it and the direction of change of momentum is in the direction of the force.

· Teacher to solve example 3.6 on pages 68, 69 of the textbook.

· Students to solve problem 3.8 on page 83 of the Textbook.

· Ask the students to try this numerical. Two cars of mass one ton (= 1000kg) are moving with a velocity of 100km/hr. Momentum of one car changed in 6 seconds and the second car’s momentum changed in 1.5 seconds. Finally both cars come to rest. Calculate the magnitude and direction of acceleration produced in both the cars and hence the magnitude and direction of applied force.

· Share the ‘USEFUL INFORMATION’ on pgs 68, 69 of

/answers and MCQ’s.






the Textbook. Law of conservation of momentum: pgs 69-72 · Recap momentum and rate of change of momentum. · In snooker, a player starts the game by hitting a

stationary white ball with a stick. After being hit, the white ball moves and collides with a red ball. Both the balls gain motion after the collisions. What is the initial momentum of both balls before the collision? Do they have the same value of momentum after the collision? If not, from where did the two balls gain momentum?

· What is impact of changing the momentum of objects within a small interval of time i.e. by applying sudden brakes or accelerator? Discuss the safety devices (such as packaging of fragile objects, the action of crumple zones and seatbelts) utilized to reduce the effects of changing momentum.

· Introduce the lesson by asking the questions: what will change if one object collides with another object, like the snooker balls, cars on the road, particles of gas, etc. In all the above cases, it is likely that two objects in motion collide or a stationary object will be hit by a moving object. A moving white ball pushes the red ball which is at rest and after the collision the red balls gains some motion while the white ball slows down. What changes take place in the momentum of the two balls? The momentum of the red ball before collision is zero (stationary) and it gains some momentum after the collision. How does this change in momentum occur? Before answering this question, consider the white ball which slows down after the collision? What does it mean? The momentum of the white ball decreases by a certain amount and the gain in momentum of red ball is

C.W. · Example 3.7

pg 71, 72 of the Textbook and problems.

· Evaluate students’ level of understanding and practical skills while they solve numerical problems and perform practical.

· Angle iron

2m long, 2 wooden stands having V-shaped top, steel ball, stop watch and meter rod






related to the decrease in momentum of the white ball. · Derive the relation:

m1u1+ m2u2= m1v1 + m2v2 · Ask students to utilize the above relation for different

examples when both objects are initially at rest (gun and bullet) or one is initially at rest (example of red and white snooker balls cited above) and so on.

· If possible let the students watch the explanation of third law, momentum and force on a multimedia or at least on a laptop with proper sound from the website https://www.youtube.com/watch?v=TyvX4-Ouovg

· Teacher to solve example 3.7 on pgs 71, 72 of the Textbook.

· Design a few numerical problems related to law of conservation of momentum and let the students solve them.

Practical 3 · Teacher’s demonstration using apparatus followed by

guided practice.

Unit 3 Dynamics 3.3 FRICTION · ROLLING

FRICTION · BRAKING AND

SKIDDING · ADVANTAGES

Students will be able to: · describe

frictional force and its effect on the motion of a vehicle in the context of tyre surface,

Friction: pgs 72-74 · Recap Newton’s first law of motion. · Refresh the students’ memory about the example of a

car given in the lesson on Newton’s first law. Why does the car stop if its engine is turned off? Why the ball hit by a footballer or cricketer comes to rest after covering some distance? It appears that all these objects negate Newton’s first law of motion (which is not correct of course) because apparently there is no force opposing their movement, or is there any force the students are

· Ask ‘Quick

Quiz’ on page 74 of the Textbook to evaluate students’ understanding of the concept of friction.

· Physics


https://www.youtube.com/watch?v=TyvX4-Ouovg






AND DISADVANTAGES OF FRICTION

· METHODS OF REDUCING FRICTION

Practical 4 · Investigate the

relation between force of limiting friction and normal reaction to find the coefficient of sliding friction between a wooden block and a horizontal surface.

road conditions including skidding, braking force

· graphically represent the relationship between the external force and the frictional force, derive a relationship between the friction and normal force

· experimentally find the coefficient of sliding friction

· identify the relationship between the load and friction by sliding a trolley carrying different loads with the help of spring balance on

familiar with? Roll a ball on a flat surface (the floor of the classroom) and when it stops, ask why the ball could not keep its state of motion. Is there any force which acts against the motion of the ball? It’s due to the force of friction.

· Teacher to explain the cause of stopping force or friction in the above example by drawing figure 3.17.

· Explain static friction, limiting value of friction and relation of friction to weight and contact force with the example of a block placed on a table and connected to weights placed in a pan by a string passing over a frictionless pulley by varying the value of weights and mass of the block (Teacher to draw the figures 3.13 on the board). Analyse the graphical relation between applied force and frictional force.

· Derive the relation to find the limiting friction: Fs=µR Let the students explain why R=mg and hence utilize the value of R to find out Fs=µmg.

· Explain µ and its dependence on the nature of surfaces sliding against each other with the help of the table on page 73.

· Teacher to solve problem 3.9 on pg 83 of the Textbook. · Design a few numerical problems related to friction and

let the students solve them. Practical 4 · Teacher’s demonstration using apparatus followed by

guided practice. Rolling Friction, Braking and Skidding: pgs 74, 75 · Recap friction and coefficient of friction. · Drag the chair or table and ask the students: What

C.W. · Solution of

numerical problems.

· Ask ‘Quick

Quiz’ on page 75 of the

· Practical Notebook (9th & 10th)

· Marker · Board

· Horizontal plane, weight box, pulley, wooden block, pan,






different surfaces

· demonstrate that rolling friction is much lesser than sliding friction

· describe rolling friction

· describe the importance of gripping force

· describe advantages and disadvantages of friction in real – world situations, as well as methods used to increase or reduce friction in these situations

makes it difficult to drag the chair/table? Students definitely know the answer. Ask the students: Can you suggest a way to move the table smoothly by applying even less force.

· Briefly explain the state of transportation before the invention of wheel. Ask the students: What is the Physics behind the utility of wheel?

· Explain why rolling friction is much smaller than the sliding friction with the help of examples from daily life.

· Explain why friction is necessary to move and stop a car? Ask the students: What will happen if brakes are applied to a fast moving car suddenly? Explain skidding with the help of examples.

· Students to do the ‘Mini Exercise’ on page 75 of the Textbook.

· Ask the students, is rolling friction less than sliding friction? Why is it so? Can you give some examples to justify your answers? Can you think of an experiment to prove this claim?

· Help students to identify the relationship between the load and friction by sliding a trolley carrying different loads with the help of spring balance on different surfaces.

· Demonstrate it by measuring the force of limiting friction for sliding object on horizontal plane and then measure a rolling the force of limiting friction for the same object by placed over rollers on the same horizontal plane. Let the student compare the values of limiting friction for the both the cases.

Advantages and Disadvantages of Friction: pgs 75, 76 · Recap sliding and rolling friction.

Textbook to evaluate students’ understanding of the concept of rolling friction.

· Evaluate practical skills of students.

· Evaluate students understanding of friction while they participate in group discussion and share their views with the class.

C.W. · Students to

solve the worksheet.

thread, spring balance and meter rod






· Students are already familiar with the concept of static friction, rolling friction and skidding. Make two groups and ask them to make a list of advantages and disadvantages of friction in real – world situations (e.g. advantages of friction on the surface of car tyres (tyre tread), cycling, parachute, knots in string; disadvantages of friction between moving parts of industrial machines and on wheels spinning on axles) and suggest ways of increasing and reducing friction according to the need after group discussion. Students to share their findings with the class. Teacher to share some points.

· Initiate a discussion in the class to find ways to reduce friction. Ask students to make a list of methods to reduce friction.

· Revise the concepts taught in Unit 3 so far and design a worksheet based on these concepts.

· Students to solve worksheet independently. Note: The topic Uniform Circular Motion will be taught with Unit 5.

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