9 Friction

8/3/2019 9 Friction

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Read this article and answer the following questions.

1) Friction is a force that opposes the motion or movement of an object when theobject is in contact with another object or surface.

2) Friction results from two surfaces rubbing against each other or moving relative toone another.

3) It can hinder(to make it difficult ) the motion of an object or prevent an object frommoving at all.

4) The strength of frictional force depends on the nature( types) of the surfaces that arein contact and the force pushing them together.

5) Frictional force is usually related to the weight of the object or objects. In casesinvolving fluid friction, the force depends upon the shape and speed of an object as itmoves through air, water, or other fluid.

6) The direction of the frictional force is always opposite to the direction of movement ofan object. Frictions acts in the opposite direction of movement.

A) THE EFFECTS OF FRICTION

The effects of friction are :-1) Friction between two surfaces will make the surfaces warm because friction

can produce heat. For examples, rub your palms together . Your palms will feelwarm because friction produces heat.

2) Friction opposes the motion. For examples, it is very hard to push or pulls a heavyobject because friction opposes the motion.

3) Friction cause wear and tear. For examples , when we rub an eraser against asurface . the eraser becomes smaller.

4) Friction makes a moving object slow down and stop. For examples, if we roll aball on the floor, it moves and gradually stops. This is because there is friction

between the marble and the floor.5) Friction makes an object to stay in a stationary position.

B ) FACTORS THAT EFFECT FRICTION

1. Friction depends on the condition of the surfaces that are rubbing against eachother.

2. Smooth surfaces cause smaller friction while rough surfaces cause greaterfriction.

3. This is the reason why we find it hard to push or pull a heavy box along a roughsurface than along a smooth surface.

4. The type of surface affects the distance moved by the object.5. If we roll a marble on different surfaces, it moves the furthest on the smoothest

surface and the slowest on the roughest surface.6. Friction also depends on the weight of an object.7. A heavier object exerts a greater frictional force.

c) THE ADVANTAGES OF FRICTION 1. Friction can be useful in our everyday life.2. Friction allows walking or running without slipping.3. If there is no friction, we will not be able to walk or run on the ground.4. Friction allows vehicles to travel on the road safely.5. The brake system in vehicles makes use of friction to slow down.

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6. Friction enables us to hold things because it prevents the object from moving.7. Friction enables us to sharpen a knife and other instruments.

D) DISADVANTAGES OF FRICTION.

1. Friction can be a problem in our daily life.2. Friction causes surfaces which are touching each other to wear out.3. For example, the sole of shows and tyres of cars or bicycles are worn out as a

result of friction.4. Worn out tyres are dangerous because they can slide and skid easily causing

accidents to occur.5. Friction produces heat in machines. This heat can damage some parts of the

machines.6. Friction also causes wasting of energy. Greater energy is needed to overcome

the force of friction to make things move.

E) WAYS TO REDUCE FRICTION.

1. There are several ways to reduce friction.2. Friction can be reduced by using rollers or ball bearings.3. Rollers or ball bearings reduce friction because they reduce the surfaces that are

touching each other.4. Friction can be reduced by using lubricants such as oil, wax, or grease.5. Friction also can be reduced by using talcum powder or air cushion.6. Another way of reducing friction is by smoothing the surfaces.7. Friction also can be reduced by using an aerodynamic shape.

F) WAYS TO INCREASE FRICTION.

1. Friction ca ben very useful in everyday life.2. Sometimes we need to increase friction for safety.3. For example, vehicles need more friction to prevent skidding.4. Friction can be increased by using a rough material or by making patterns on the

surface.5. Roads are made rough to increase friction so that motor vehicles using them will

not skid easily.6.7. Roads are made by using tar which is mixed with pebbles.8. This mixture is rough so that friction between the tyres and the road surface is

increased.9. Patterns on the surfaces of tyres are made to increase friction between the tyres

and the road surface.10. Special patterns can also be seen on the soles of shoes. These patterns help to

increase friction exerted by the soles of the shoes.

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Circle the correct answers.

State that friction is a type offorce

1. What is a friction ?

A a type of energyB a type of forceC a type of apparatusD a type of object

2. What causes friction?

A Movement of one surface overanother

B Collision between two objectsC Heat produced by an objectD Signs of wear shown on the

surface of an object

3. Which of the following statementsbest to describes about friction?

A Friction is a type of forceB Friction can change the colour of

an objectC Friction is of no use in our daily life

D Friction makes a moving object tomove faster

4. Diagram below shows a moving ball.

Which of the following is the direction ofthe frictional force

A P B QC R D S

5. Diagram below shows a woodenblock being pulled on a surface.Among directions A,B,C and D ,which one shows the direction ofthe friction acting on the woodenblock?

Which of the following will increase thefriction that acts on an object?

I Weight of the object increasesII Have moist surfaceIII The object changes its shapeIV The object changes its colour

A I onlyB I and III only

C II and III onlyD III and IV only

6. Which of the following are thefactors that affect friction?

I Length of a surfaceII Condition of the surfaceIII Thickness of the objectIV Weight of an object

A I and III onlyB II and IV onlyC I,II ad III onlyD II,III and IV only

7. Which of the following surfacesproduces the most friction?

A NewspaperB Sand paperC GlassD Plywood

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8. Which of the following surfaces

produces the greatest friction?

A CementB WoodC SandpaperD Tile

9. A ball is rolled alternately on fourtypes of surfaces. Which of thefollowing situation will produce thelargest frictional force exerted on theball?

10. An object is moving on four differenttypes of surfaces. The condition ofthe surfaces is shown in the tablebelow.

Surface Condition ofsurface

W Dry

X Watery

Y OilyX Dusty

On which surface will the object stopthe earliest?

A WB XC YD Z

11. Table below shows the distancemoved by a marble on four types ofsurfaces.

Surface P Q R S

Distancemoved

by themarble(cm)

18 20 12 25

Which surface exerts the largestfrictional force?A PB QC RD S

12. Four objects of different shapes roll

on the same surface. Frictionbetween which object and surfacesis the smallest

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13. Diagram below shows four boxes ofdifferent weights.

Which box will exert a smallest frictionalforce when they are pulled on thecement?

A PB QC R

D S

14. The following information shows fourtypes of surfaces

Jonathan rolls a marble on the surfacesabove. Which surface will cause themarble to move the furthest?

A PB QC RD S

15. Table below shows the condition ofsurfaces R,S,T and U

Surface Condition ofsurface

R Wet

S DyT Greasy

U Dusty

Which surface will produce the smallestfriction ?

A R B S

C T D U

Describe the effect of friction

16. What is the effect of frictional forceon the moving object ?A It moves faster

B It stops immediatelyC It becomes slower and finally stopsD It moves to the opposite direction

17. Which of the following is an effect offriction?

A Heat is producedB A moving object moves fasterC A coconut falls from the treeD A floor becomes muddy

18. Which of the following shows theeffects of friction?

A the sole of the shoes becomeswear and tear

B A metal rod becomes bentC Colour of an object changesD A digital watch stop functioning

19. Jamal could not open the lid of a jarcontaining jam. Which of the

following best explains this situation?

A He is wearing a gloveB The lid is sealed offC There is dust on the lidD His hand is oily

20. Which of the following situationsdescribes the effect of friction?

I Surface of tyres become baldII Difficult to move a box that is fullIII A metal rod become bentIV A door closes by itself when

strong wind blows

P : Cement floorQ : Sand paperR : CarpetS : Mirror

A I and II onlyB I and III onlyC I,II and III onlyD I,II,III and IV

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Describe ways to reducefriction

21. Which of the following can be used

to reduce friction?

I SandII WaxIII OilIV Ball bearing

A I and II onlyB II and IV onlyC I and III onlyD II,III and IV only

22. Which of the following are the waysto reduce friction ?

I Using ball bearingsII Using lubricantsIII Using air cushionIV Using salt solution

A I and III onlyB II and IV only

C I,II and III onlyD II,III and IV only

23. The picture below shows a workerpushing a heavy load.

Which of the following methods can beused to make it easier to move theheavy load?

I Place rollers under the heavy loadII Coat the bottom of the load with oilIII Pull the load using a rope

IV Place the load on a trolley withwheels.

A I and II onlyB I,II and IV onlyC I,II and III onlyD I,II,III and IV

24. Which of the following are ways toreduce friction ?

I Using rollersII Using air cushionIII Using greaseIV Using sandpaper

A I and III onlyB II and IV onlyC I,II and III only

D II,III and IV only

25. Friction can be reduced by using..

I ball bearingsII using lubricants such as oil, wax

and greaseIII using talcum powderIV using an aerodynamic shape

A I and II onlyB I and III only

C II and III onlyD I,II ,III and IV

26. Diagram below shows a way toreduce friction in an object.

Reducing friction enables the parts ofthe object to…

A roll smoothlyB expandC start movingD be replaced regularly

Ball bearings

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Describe ways to increasefriction

27. Which of the following are the bestways to increase friction?

I using a rough materials on thesurfaces that are rubbing on eachother.

II making patterns on the surfaces thatare rubbing on each other.

III using grease on the surfacesIV using lubricants on the surfaces

A I and II onlyB II and III onlyC III and IV onlyD II and IV only

State the advantages offriction

28. Diagram below shows the pattern on

a car tyre.

What is use of the pattern on the tyre?

A To make the tyre heavierB To make the tyre last longerC To make the tyre exert more frictionD To make the tyre look more beautiful

29.. What force causes an object to stayin a stationary position ?

A GravityB A push

C FrictionD A pull

30. In which of the following actions isfrictional force used ?

I Polishing a metal objectII Sharpening a knifeIII Lighting a match

A III onlyB I and II onlyC I and III onlyD I,II and III

31. Diagram below shows the pattern onthe sole of the shoe.

The pattern is made to…

A reduce frictionB increase friction

C beautify the showD reduce cost

32. Which of the following actions aredifficult to perform without frictionalforce?

I sharpening a knifeII turning a doorknobIII swimming in a poolIV stopping a moving object

A I and II onlyB I and IV onlyC I,II and IV onlyD II,III and IV only

33. Which of the following will enable theheavy object to be pushed easier ?A Washing the floor with waterB Using a rope to pull the objectC Placing rollers underneath the

object

D Wrapping the object with sandpaper

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State the disadvantages offriction

34. A frictional force causes the moving

object to

A move fasterB move slowerC change directionD become heavier

36. Which of the following forces allowsus to walk or run without slipping?

A Magnetic

B KineticC FrictionD Gravity

37. Which of the following are thedisadvantages of friction?

I Friction causes us to slip easilyII Friction produces heat in

machinesIII Friction causes wasting energyIv Friction causes surfaces whichare touching each other to wear out

A I and III onlyB II and IV onlyC I,II and III onlyD II,III and IV only

EXTRA QUESTIONS

38. Cube X is pushed forward as shownin diagram below.

Which arrow labelled A,B,C and Dshows the correct frictional force acting

on cube X ? 39. What is the effect of frictional force

on the moving object ?

A It moves fasterB It stops immediatelyC It becomes slower and finally

stopsD It moves to the opposite direction

40. Among the following,which does notneed frictional force ?

A Ice skatingB Climbing a treeC Sharpening a knifeD Turning a door knob

Describe ways to increase friction

27. Which of the following are the best waysto increase friction?

I using a rough materials on the surfacesthat are rubbing on each other.

II making patterns on the surfaces that arerubbing on each other.

III using grease on the surfacesIV using lubricants on the surfaces

A I and II onlyB II and III onlyC III and IV onlyD II and IV only

State the advantages of friction

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28. Diagram below shows the pattern on a

car tyre.

What is use of the pattern on the tyre?

A To make the tyre heavierB To make the tyre last longer

C To make the tyre exert more frictionD To make the tyre look more beautiful

29.. What force causes an object to stay in astationary position ?

A GravityB A pushC FrictionD A pull

30. In which of the following actions isfrictional force used ?

I Polishing a metal objectII Sharpening a knifeIII Lighting a match

A III onlyB I and II onlyC I and III onlyD I,II and III

31. Diagram below shows the pattern on thesole of the shoe.

The pattern is made to…

A reduce friction

B increase frictionC beautify the showD reduce cost

32. Which of the following actions aredifficult to perform without frictionalforce?

I sharpening a knife

II turning a doorknobIII swimming in a poolIV stopping a moving object

A I and II onlyB I and IV onlyC I,II and IV onlyD II,III and IV only

33. Which of the following will enable theheavy object to be pushed easier ?A Washing the floor with waterB Using a rope to pull the object

C Placing rollers underneath the objectD Wrapping the object with sand paper

State the disadvantages of friction

34. A frictional force causes the movingobject to

A move fasterB move slowerC change directionD become heavier

36. Which of the following forces allows usto walk or run without slipping?

A MagneticB KineticC FrictionD Gravity

37. Which of the following are thedisadvantages of friction?

I Friction causes us to slip easilyII Friction produces heat in machinesIII Friction causes wasting energyIv Friction causes surfaces which aretouching each other to wear out

A I and III onlyB II and IV onlyC I,II and III onlyD II,III and IV only

EXTRA QUESTIONS

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38. Cube X is pushed forward as shown indiagram below.

Which arrow labelled A,B,C and D showsthe correct frictional force acting on cube X ?

39. What is the effect of frictional force onthe moving object ?

A It moves fasterB It stops immediatelyC It becomes slower and finally stopsD It moves to the opposite direction

40. Among the following, which does notneed frictional force?

A Ice skatingB Climbing a treeC Sharpening a knifeD Turning a door knob

41 Friction is a force that ...

A moves a stationary object.B changes the direction of a moving object.C opposes the movement of an object.D changes the shape of an object.

42 Which of the following surfaces causesthe largest friction?A TileB Sandpaper

C TarD Paper

43 Which of the following are factors thataffect friction?

I The condition of the surfacesII The size of the objectIII The weight of the objectIV The area of the surfaces

A II onlyB I and III only

C I, II, and IV onlyD II, III, and IV only

44 Lee Meng rolled a marble on a cementsurface. The marble stopped after rollinga distance of 80 cm. Then he rolled thesame marble on the following surfaces.

P - Glass

Q - GrassR – Manila cardS - Plank

On which surface did the marble roll adistance of more than 80 cm?

A P and QB Q and RC P, Q and RD P, R and S

45 Which of the following is an effect offriction?

A It makes a moving object move faster.B It makes a moving object slow down.C It causes a moving object to change

direction.D It changes the shape of an object.

46. Diagram 5 shows the raised pattern onthe surface of a tyre.

Diagram 5

The pattern is made on the surface ofthe tyre to ...

A make the tyre stronger.B increase friction.C decrease friction.D reduce costs.

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47. Which of the following activities are

difficult to perform without friction?

I Sharpening a knifeII Turning a door knob

III Swimming in a poolIV Slowing down a moving bicycle

A I and II onlyB I and IV onlyC I, II and IV onlyD II, III and IV only

48. Diagram 6 shows a worker pushing aheavy load.

Diagram 6

Which of the following methods can beused so that it is easier to move theload?I Pull the load using a rope.II Place rollers under the load

III Coat the floor with oil

A II onlyB I and II onlyC II and III onlyD I, II and III

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Nyatakan hubungan antara daya geseran dan jenis permukaan ………………………………………………………………………….......................................………………………………………………………………………………………………

(e) What does the pupil want to find out from this investigation?Apakah yang ingin dikaji oleh murid tersebut dalam kajian ini.

………………………………………………………………………………………………….………………………………………………………………………………………………….

2.

During a fair test,a group of pupils push a ball on three different types of surface. Theresult is as follows.Semasa satu kajian yang adil dijalankan, sekumpulan pelajaran menolak sebiji bola di atas 3 jenis permukaan yang berbeza. Keputusannya adalah seperti di bawah.

(a) What is the aim of the investigation ?( Nyatakan tujuan kajian ini dijalankan ) ……………………………………………………………………………………………………………………………………………………………………………………………………

(b) On which surface,does the ball move the least ? ( Di permukaan manakah , bola bergerak paling dekat) .......................................................................................................................................................................................................................................................................

c) What happens to the distance travelled by the ball ,if the type of surface is smoother?(Apakah yang akan terjadi kepada jarak pergerakan bola apabila jenis permukaan bertambah licin ?) ……………………………………………………………………………………………………………………………………………………………………………………………..

(d) State one information gathered in this investigation.(Nyatakan satu maklumat yang perlu dikumpulkan dalam kajian ini)

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………………………………………………………………………………………………

(e) What conclusion can be made from the information in the table above ?( Apakah kesimpulan yang dibuat berdasarkan jadual di atas? )

……………………………………………………………………………………………………………………………………………………………………………………………..

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