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CHAPTER 5 MOTION DATE/TARIKH:…………………….

5.1 THE MOTION OF VEHICLES ON LAND/PERGERAKAN KENDERAAN DI DARAT.

Land vehicles can be divided into two groups/Kenderaan di darat terbahagi kepada dua kumpulan iaitu:

(a) Vehicles without engine such as bicycles kenderaan tanpa enjin seperti basikal.

Vehicles without engine use the energy of humans or animals to move. Kenderaan tanpa enjin guna tenaga manusia atau haiwan untuk bergerak

(b) Vehicles with engine such as cars, buses and motorcyclesKenderaan berenjin seperti kereta, bas, motosikal

Vehicles with engine use fuels such as petrol and diesel to make them work. Kenderaan berenjin guna bahan api seperti petrol dan disel untuk menggerakkan nya.

Principle of Operation of Vehicles with Engines(a) There are three types of engines, i.e. the four-stroke petrol engine, the four-stroke

diesel engine and the two-stroke petrol engine. Terdapat tiga jenis enjin iaitu enjin petrol empat lejang, enjin disel empat lejang dan enjin petrol dua lejang

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(b) How a four-stroke combustion works in a four-stroke petrol engineBagaimana kerja-kerja pembakaran empat lejang dalam enjin petrol empat lejang.

Figure/rajah Stroke/lejang Figure/rajah Stroke/lejang

(1) Induction stroke lejang aruhan-the piston moves down.-the inlet valve opens-the exhaust valve closes-the mixture and air is sucked into the cylinder.

-Omboh bergerak ke bawah-injap masuk terbuka.Injap ekzos tertutup-campuran petrol dan udara disedut masuk

(2) Power stroke Lejang kuasa.-A spark from the spark plug ignites the compressed mixture causing it to explode-Hot exhaust gases from the explosion expand rapidly forcing the piston down the cylinder

-Percikan api dari palam pencucuh menyalakan campuran yang dimampatkan menyebabkan ia untuk meletup-Gas ekzos yang panas daripada letupan mengembang dan memaksa omboh dalam silinder turun.

(2) Copression stroke Lejang mampatan.-Piston moves up-inlet and exhaust valve close-The mixture of petrol and air is compressed

-Omboh bergerak ke atas-injap masuk dan injap ekzos tertutup-campuran petrol dan udara dimampatkan

(4) Exhausted stroke Lejang ekzos-Piston moves up-The exhaust valve opens the inlet valve closes.-The exhaust gases are forced out of the cylinder through the open exhaust valve

-Omboh bergerak ke atas-injap ekzos terbuka dan injap masuk tertutup-Gas ekzos yang panas dipaksa keluar dari omboh melalui iinjap ekzos.

(c) The table below shows the differences between the four-stroke petrol engine and the four-stroke diesel engine.

Structue of four stroke petrol enginesturktu enjin petrol empat lejang

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Characteristic Four-stroke petrol engine Four-stroke diesel engineCycles Induction stroke

• The piston moves down.• The inlet valve opens and the b exhaust

valve closes.• The mixture of petrol and air is sucked into the

cylinder.-Omboh bergerak ke bawah-Injap masuk terbuka dan injap ekzos tertutup-Campuran petrol dan udara disedut masuk ke

dalam silinder

Compression stroke• The piston moves up.• Both valves close.• The mixture of petrol and air is compressed.-Omboh bergerak ke atas-Kedua-dua injap tertutup-Campuran petrol dan udara dimampatkan

Power stroke• Both valves close.• A spark from the spark plug ignites the

compressed mixture causing it to explode,• Hot gases force the piston down.-Kedua-dua injap tertutup.-Percikan api dari palam pencucuh

menyalakan campuran menyebabkan ia melatus.

-Gas panas memaksa omboh bergerak ke bawah.

Exhaust stroke• The piston moves up.• The exhaust valve opens and the inlet valve

closes.• The exhaust gases are forced out of the

cylinder,-Omboh bergerak ke atas.-Injap ekzos terbuka dan injap masuk

tertutup.-Gas ekzos ditolak keluar dari silinder.

Induction stroke• The piston moves down.• The inlet valve opens and the exhaust

valve closes.• Air is sucked into the cylinder.-Omboh bergerak ke bawah-Injap masuk terbuka dan injap ekzos

tertutup-Udara disedut masuk Ke dalam silinder

Compression stroke• The piston moves up.• Both valves close.• Air is compressed and becomes very

hot.• Diesel is injected into the cylinder.-Omboh bergerak ke atas-Kedua-dua injap tertutup-Udara dimampatkan dan menjadi sangat

panas-Disel disuntik masuk ke dalam silinder.

Power stroke• Both valves close.• The hot mixture of compressed air

and diesel burns, releasing hot exhaust gases.

• Hot gases force the piston down.-Kedua-dua injap tertutup.-Campuran gas panas termapat dan

disel terbakar, membebaskan gas ekzos yang panas.

-Gas panas memaksa omboh bergerak ke bawah.

Exhaust stroke• The piston moves up.• The exhaust valve opens and the inlet

valve closes.• The exhaust gases are forced out of

the cylinder.Omboh bergerak ke atas.-Injap ekzos terbuka dan injap masuk

tertutup.-Gas ekzos ditolak keluar dari silinder

Thickness of the wall of the cylinder

Thin Thicker

Efficiency Less efficient More efficient

Uses Light vehicles like car Heavy vehicles like lorry, bus.

Power More powerful Less powerful

Exhaust gases released Releases more harmful exhaust gases Releases less harmful exhaust gases

Fuel injectorpenyuntik bahan api

Figure 5.3 Four stroke diesel engine

Figure 5.2 Four stroke dpetrol engine

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(d) Two stroke Petrol engine

How a two stroke combustion cycle works in a two stroke petrol engine

Upstroke/lejang naik Downstroke/lejang turun

-When the piston is at the top of the cylinder, the mixture of the petrol and the air above it is compreesed.-The exhauset and transper ports are closed but the inlet port is open.-A fresh mixture of petrol and air is sucked into the crankcase through the open inlet port-A spark from the spark plug ignites the compressed mixture of petrol and air causing it to explode

-Apabila omboh berada di bahagian atas silinder, campuran petrol dan udara di atasnya dimampatkan.-Salur keluar dan salur penghantar ditutup tetapi salur masuk adalah terbuka.-Satu campuran petrol dan udara disedut ke dalam kotak engkol melalui salur masuk yang terbuka-Percikan api dari palam pencucuh menyala campuran petrol dan udara yang dimampatkan dan menyebabkan ia meletup

-Hot gas from the explosion expand rapidly forcing the piston down the silinder.-The inlet port closes and compress the mixture of petrol and air in the crankcase.-The piston is at the bottom of the silinder, the compressed mixture below it passes through the transfer port into the cylinder above the piston.-The exhaust port is open and the exhaust gas are pushed out.

-Gas panas dari letupan mengembang dan memaksa omboh bergerak ke bawah silinder.-Salur masuk ditutup dan memampatkan campuran petrol dan udara dalam kotak engkol.-Omboh di bahagian bawah silinder , campuran yang termampat di bawahnya melalui salur penghantar ke dalam silinder di atas omboh.-Liang ekzos dibuka dan gas ekzos ditolak keluar.

The table below shows the comparison between the four-stroke and the two-stroke engine.

Four stroke engine Two stroke engineIn each cycle, the piston moves four strokes, two upward strokes and two downward strokes.

In each cycle, the piston moves two strokes, one upward stroke and one downward stroke.

Power is released only on the third stroke, also called the power stroke.

Power is released on every upward stroke.

Two stroke petrol engine

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Combustion of fuel takes place only on the third stroke. During this stroke, an upward stroke, sparks (electrical) given off by the spark plugs ignite the air-fuel mixture.

Combustion of fuel takes place on every upward stroke of the piston. Sparks (electrical) given off by the spark plugs ignite the air fuel mixture.

Generally more efficient because the combustion process is more complete.

Less efficient because the combustion process is incomplete.

The design is complex and bulky. The design is simple and less complex.

Exercise 5.1

1. Which of the following about a four-stroke diesel engine is true? Yang manakah antara berikut mengenai enjin disel empat lejang?

I Spark plugs are not needed/Palam pencucuh tidak diperlukan.II More exhaust gases are released/Lebih banyak gas ekzos dibebaskanIII It is more economical/Ianya lebih ekonomi(jimat)A. I and II only B. I and III only C. II and III only D. I, II and III

1. In the four-stroke diesel engine, the mixture of air and fuel is burnt in...Dalam enjin disel empat lejang, campuran udara dan bahan api dibakar dalam….A. the power stroke. B. the intake stroke. C . the exhaust stroke. D the compression stroke.

2. The four-stroke diesel engine has cylinders with thicker walls than those of the four-stroke petrol engine because... Enjin disel empat lejang mempunyai silinder yang lebih tebal daripada enjin petrol empat lejang kerana……..A. the engine uses spark plugs./Enjin guna palam pencucuhB. the exhaust stroke of the engine is more powerful./Lejang ekzos lebih berkuasa.C. the pressure in the cylinders during the compression stroke is very high. Tekanan dalam silinder semasa lejang mampatan sangat tinggiD. the power stroke contains very hot exhaust gases./Lejang kuasa mengandungi gas

ekzos yang sangat panas.

Subjective

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Figure 11.Figure 1 shows two different strokes in the four-stroke petrol engine. Rajah 1 menunjukkan dua perbezaan dalam enjin petrol empat lejang

(a) Name the strokes shown in Figure 1. / Namakan lejang-lejang dalam rajah 1. i. P: ____________________________ii. Q: _________________________

(b) What happens in stroke Q?/Apakah yang berlaku dalam lejang Q?

_________________________________________________________________

(c) State two difference between the four stroke diesel engine and the four-stroke petrol engine.

Nyatakan dua perbezaan antara enjin disel empat lejang dan enjin petrol empat lejang.

__________________________________________________________________

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Tarikh/Date……………………..

5.2 The Concept of Speed, Velocity and Acceleration Konsep bagi Laju, Halaju dan pecutan

1.Speed is the distance travelled per unit time./Laju ialah jarak yang dilalui per unit masa.

Speed = distance Laju= Jarak yang dilalui Time masa yang diambil

2. Velocity is the rate of change of distance travelled in a specific directionHalaju adalah kadar perubahan jarak perjalanan ke arah tertentu.. Velocity = The change of distance in specific direction Time taken

Halaju = perubahan jarak dalam arah tertentu Masa yang diambil

3.The SI unit of velocity and speed is ms-1./Unit SI bagi halaju dan laju ialah ms-1

4.Acceleration is the rate of change of velocity./Pecutan ialah kadar perubahan halaju.5.The SI unit of acceleration is ms-2/Unit SI bagi pecutan ialah ms-2

Acceleration = final velocity - initial velocitytime taken

Pecutan = halajau akhir - halaju awal Masa yang diambil

Activity 5.2: Use ticker timer to measure velocity/Menggunakan jangka masa detik untuk mengukur halaju.

Procedure ticker timer Ticker tape trolley

Incline plane

Ticker timer vibrate 50 tick in one secondJangka masa detik bergetar 50 detik dalam masa satu saat.

Dot tick

Result:

Activity 5.2 and 5.3 of the practica book on page 64, 65 and 66

Wooden blockPower

pack

. . . . . . . . . . . . . . . . . . . . .

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Calculation:

Activity 5.3Result:

Calculation:

Exercise 5.2

1. The ticker tape provided below record the velocity of a trolley in an experiment. By using your ruler, calculate initial velocity, final velocity and acceleration of the trolley (The current supplied to the ticker timer is 50 Hz).

Pita detik di bawah merekodkan halaju troli dalam satu eksperimen. Dengan menggunakan pembaris, hitungkan halaju awal, halaju akhir dan pecutan troli.(arus elektrik yang dibekalkan kepada jangka masa detik ialah 50Hz)

Initial velocity = Final velocity =

Acceleration =

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3. The diagram below shows part of a ticker tape of a moving trolley. What is the type of motion of the trolley?Rajah dibawah menunjukkan bahagian pita detik bagi satu pergerakan troli. Apakah jenis pergerakan troli tersebut?

Underline the correct unswer. Answer: acceleration/deceleration/constant velocity

4. A car moves with a constant velocity of 20 ms-1. The car accelerates and reaches a velocity of 50 ms-1 in 6 seconds. What is its acceleration?Sebuah kereta bergerak dengan satu halaju malar 20 ms-1. Kereta tersebut kemudian memecut dan mencapai halaju 50 ms-1. Dalam masa 6 saat. Apakah pecutan nya?Answer:

5. The diagram below shows two strips of ticker tape of a moving trolley. The current supplied to the ticker timer is 50 Hz. Calculate the acceleration of the trolley.Rajah di bawah menunjukkan dua pita detik bagi satu pergerakan troli. Arus elektrik yang dibekalkan kepada jangka masa detik ialah 50Hz. Hitungkan pecutan troli tersebut.

Initial velocity=

Final velocity=

Acceleration=

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Tarikh/date………………………5.3 The Concept of Inertia

The inertia of an object is the ability of the object to maintain its stationary position or its movement.Inertia bagi sesuatu objek ialah keupayaan objek tersebut untuk mengekal keadaan asalnya sama ada diam atau bergerak dengan halaju seragam.

If the mass of the object is bigger, the inertia will be bigger. Jika jisim objek besar, maka inertianya juga besar.

The safety features used in vehicles/ Ciri-ciri keselamatan yang digunakan di dalam kenderaan(a) Seat belts- protect the driver and passengers from injuries when the car

suddenly stops or crashes. tali pinggang keledar-melindungi pemandu dan penumpang dari tercedera

apabila kerata berhenti secara tiba-tiba

(b) Headrest- protects the neck of the driver or passenger from injuries when the car is hit from back

sandaran kepala-melindungi leher pemandu atau penumpang dari tercedera jika kereta dilanggar dari belakang

(c) Air bag- protect the driver and passengers from banging the dashboard when the car suddenly stops or crashes.

Beg udara-melindungi pemandu dan penumpang dari terhantuk ke dashboard jika kereta terhenti secara tiba-tiba

Exercise 5.31. Which of the following affects the inertia of an object?/Yang manakah antara berikut

mempengaruhi inertia sesuatu objekA Base area of the object B Volume of the object Luas Dasar objek Isipadu objek

C Mass of the object D Size of the object Jisim objek Saiz objek

2. The diagram below shows four cans filled with different quantities of soil. These four cans are pushed at the same time. Which of the following cans,A,B,C or D, will be the last to stop?

Rajah di bawah menunjukkan empat tin yang berisi pasir dengan kuantiti yang berbeza. Keempat-empat tin tersebut ditolak pada masa dan ketinggian yang sama. Yang manakah antara A, B, C dan D akan terakhir berhenti berayun

Experiment 5.1 of the practical book .page 68 and 69

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Tarikh/date:………………………. 5.4 The Concept of Momentum

1.The momentum of an object is the product of its mass and velocity. Momentum = mass x velocityMomentum sesuatu objek ialah hasil darab jisim dan halajunya. Momentum = jisim x halaju.

2.The SI unit of momentum is kg ms-1/Unit SI nya ialah kg ms-1

3.The momentum of an object is bigger if its mass is bigger and its velocity is higher. Momentum bagi sesuatu objek adalah besar jika jisim lebih besar dan halajunya lebih

tinggi.

The Principle of Conservation of Momentum

This principle states that the total momentum of two or more objects before a collision is equal to the total momentum after the collision provided no resultant external force acts on the objects.Prinsip ini menyatakan yang jumlah momentum bagi dua atau lebih objek sebelum perlanggaran adalah sama dengan jumlah momentum selepas perlanggaran jika tiada daya luar bertindak ke atasnya.

2.A force is required to change the momentum of an object. Daya diperlukan untuk mengubah momentum bagi sesuatu objek3. The resultant force acting on an object is equal to the rate of change of its momentum. Daya paduan yang bertindak ke atas sesuatu objek adalah sama dengan kadar

perubahan momentum

Resultant force = change in momentum Daya paduan = perubahan momentumtime taken masa yang diambil

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Tarikh/Date……………….5.5The Concept of Pressure

1. Pressure is defined as force per unit area./Tekanan ialah daya per unit luas

Pressure = force tekanan = Daya Area Luas

3.The SI unit of pressure is newton per square meter (N/m2) or pascal (Pa). Unit SI bagi tekanan ialah (N/m2) or pascal (Pa).4.The pressure acting on a surface depends on:

Tekanan yang bertindak ke atas sesuatu permukaan bergantung kapada: (a) the force acting on the object; /Daya yang bertindak ke atas objek (b) the area on which the force is acting./Luas permukaan dimana daya bertindak

The Application of pressure in everyday life• A sharp knife cuts easily• Carrying a heavy bag is more comfortable if the strap is broad• Pisau yang tajam lebih senang memotong• Membawa beg yang berat lebih selesa jika tali begnya lebar

Exercise5.51. Define Pressure.

Pressure= force/unit area

2. If the surface area greater, The pressure _________is smaller________________

3. A roller skater of mass 65 kg balance himself on one leg. If the skate touches the floor with an area measuring 5 cm2, calculate the pressure the roller skater exerts on the floor. Pressure= 650/5 =130N/cm2

4. A strong wind exerts an average pressure of 50000 Nm-2 on a glass wall. If the area of the glass is 10 m2, what is the force acting on the glass?

Pressure=force/unit area forcre =50000x10 =500000N

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Tarikh/Date…………………..5.6 Principle of Hidraulic System/Prinsip sistem hidrolik

1. The principle of transmission of pressure in fluids states that if pressure is applied to an enclosed liquid, the pressure is transmitted uniformly throughout the liquid.Prinsip pemindahan tekanan dalam bendalir menyatakan bahawa jika tekanan dikenakan kepada bendalir yang tertutup, tekanan dihantar secara seragam di seluruh cecair

2. This principle is used in the hydraulic jack and hydraulic brake.Prinsip ini digunakan dalam jek hidrolik dan brek hidrolik

3. Using this principle, the pressure acting on a small piston is the same as the pressure acting on a larger piston.

Menggunakan prinsip ini, tekanan yang bertindak ke atas omboh kecil adalah sama dengan tekanan ke atas omboh besarForce acting on the small piston = force acting on the large pistonSurface area of the small piston surface area of the large piston

P1 = P2

P1 P2

\ApplicationHydraulic jack/jek hidrolik

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Hydraulic brake/brek hidrolik

Exercise 5.6 1. State two examples of machines which operate on the principle of the hydraulic

system?

Hydraulic jack and hydraulic brake

2. In a hydraulic jack, a force of 50 N is applied to a small piston with an area of 5 cm2. (a) What is the pressure transmitted through the fluid? Pressure= 50N/5cm2 =10N/cm2

(b) If the large piston has an area of 20cm2, what is the maximum weight that the jack can lift

F/20=10 F=200N

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Tarikh/Date;……………………5.7 The Motion of Vehicle in Water

1. Water vehicles usually have streamlined shapes to reduce turbulence while moving in the water.Pengangkutan air  biasanya mempunyai bentuk yang streamlined untuk mengurangkan pergolakan semasa  bergerak di dalam air

2. Archimedes’ principle./Prinsip Archimedes Archimedes’ principle states that when an object is immersed in a fluid (liquid or gas), the

upthrust on the object is equal in size to the weight of the fluid displaced by the object. Prinsip Archimedes menyatakan bahawa apabila sesuatu objek tenggelam di dalam

bendalir (cecair atau gas), tujahan ke atas pada objek adalah sama dengan berat bendalir yang disesarkan oleh objek tersebut.

Upthrust (buoyancy force) = weight of fluid displaced

3. This principle is applied to boats, ships, hovercraft, hydrofoils and submarines.

Submarine/kapal selam(a) A submarine has ballast tanks that control the submarine, making it sink or float.

Kapal selam mempunyai tangki balast yang mengawal kapal selam, tenggelam atau timbul.

(b) The submarine will sink when the ballast tanks are filled with water.Kapal selam akan tenggelam apabila tangki balast diisikan dengan air.

(c) The submarine rises to the surface when the water in the ballast tanks are blown out.Kapal selam akan naik ke permukaan apabila air dalam tangki dikosongkan

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Hydrofoil Hovercrafts

Exercise 5.71. Figure below shows an experiment to investigate Archimedes’ principle.

Rajah dibawah menunjukkan satu eksperimen untuk mengkaji prinsip Archimedes.

The result for the experiment provided in the table belowKeputusan eksperimen adalah seperti jadual di bawah.Object WaterWeight in air/berat dalam udara = 7.0 N Weight of beaker + water = 4.0 N

Berat bikar + airWeight in water/berat dalam air = 6.0 N Weight of empty beaker = 3.0 N

Berat bikar kosongUpthrust of water /daya julangan= 7-6=1N Weight of water displaced= 1.0N

Berat air tersesar

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(a) Determine the upthrust of water and weight of water displaced on the above table.Tentukan daya julangan air dan berat air tersesar pada jadual di atas.

(b) The object appears to have lost weight in water. State the reason of apparent loss in weight ?

objek nampaknya telah kehilangan berat  di dalam air. Nyatakan sebab kehilangan ketara dalam berat objek

disebabkan oleh dayajulangan

(c) Based on the result, what is the relationship between the upthrust of the water and the weight of the water displaced?

 Berdasarkan keputusan, apakah hubungan antara daya julangan air dan berat air yang disesarkan?

Upthrust = the weight of the waterdisplaced

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Tarikh/Date:…………………..5.8 The Motion of Vehicles in the Air

1.Examples of vehicles that move in the air are hot air balloons, aeroplanes, helicopters and rockets.Contoh kenderaan yang bergerak dalam udara ialah belun udara, kapal terbang, helikopter dan roket.

2.These vehicles use Bernoulli’s principle to work.Kenderaan ini menggunakan prinsip Bernoulli untuk bergerak.

3.Bernoulli’s principle states that pressure is inversely proportional to the velocity of a flowing fluid.

Prinsip Bernoulli menyatakan yang tekanan adalah berkadar songsang dengan halaju udara (cecair) yang mengalir.(a) When the velocity of a fluid is high, the pressure is low.

Apabila halaju bendalir tinggi, tekanannya rendah(b) When the velocity of a fluid is low, the pressure is high.

Apabila halaju bendalir rendah,tekanannya tinggi.4 .Examples of the use of Bernoulli’s principle / Contoh kegunaan Prinsip Bernoulli.

(a) The flow of water through capillary tubes/Pengaliran air dalam tiub Bernoulli.

(b) The flow of air through capillary tubes/Pengaliran udara dalam tiub Bernoulli

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(c) Aerofoil shape of the wings of the aeroplane/Bentuk Aerofoil pada sayap kapal terbang.

Rocket.

Jet Engine

-Air flows under the wings slower, The air pressure is higher.-Pengaliran udara di bawah sayap kapal terbang rendah, tekanan udara adalah lebih tinggi.

-This pressure will produce higher upthrust and can cause the aeroplane move upwardsTekanan yang lebih tinggi di bawah sayap kapal terbang menghasilkan daya julangan yang tinggi dan menyebabkan kapal terbang bergerak ke atas.

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The table below shows the comparison between the rocket engine and the jet engine.

Rocket engine Jet engineCarries its own oxygen supplyBawa bekalan oksigen sendiri

Uses the oxygen of the atmosphereMenggunakan oksigen atmosfera

Can move in the Earth’s atmosphere and in outer spaceBoleh bergerak dalam atmosfera bumi dan di angkasa lepas

Can move in the Earth’s atmosphere onlyBoleh bergerak dalam atmosfera bumi sahaja

Fuel used is liquid hydrogenBahan api yang digunakan ialah hidrogen cecair

Fuel used is keroseneBahan api yang digunakan ialah karosene

Exercise 5.81. Figure below shows Bernoulli’s tube.

(a) Draw in the figure the water level in each capillary tube.