bab 2_ 2.2 latihan.pdf

1 Jarak ialah jumlah laluan yang dilalui dari satu lokasi ke satu lokasi yang lainDistance is the total path length travelled from one location to another

Kuantiti/Quantity: Skalar/Scalar Unit SI/SI unit: meter (m) 2 Sesaran ialah/Displacement is (a) jarak dalam arah tertentu./the distance in a specific direction . (b) jarak antara dua lokasi yang diukur sepanjang laluan yang paling pendek yang menghubungkannya

dalam arah tertentu.the distance between two locations measured along the shortest path connecting them in a specific direction.

(c) jarak kedudukan akhir dari kedudukan awal dalam arah tertentu.the distance of its final position from its initial position in a specified direction.

Kuantiti/Quantity: Vektor/Vector Unit SI/SI unit: meter (m)

3 Rajah di sebelah kanan menunjukkan beza antara jarak dan sesaran. Apabila Ah Chong berjalan kaki di sepanjang Jalan Baik dari rumah A ke sekolah B,The diagram on the right shows the difference between distance and displacement. When Ah Chong walked from House A to School B, along Good Road,

Jarak/Distance = Panjang laluan di sepanjang Jalan Baik

Length of the road along Good RoadSesaran/Displacement

= Panjang garis lurus AB / Length of the straight line ABRumahHouse

SekolahSchool

Jalan BaikGood Road

A

B

Rahim berjalan dari rumahnya ke simpang sejauh 1.5 km dari rumahnya. Kemudian dia berpatah balik dan berhenti di warung Pak Din yang sejauh 0.5 km dari rumahnya. Rahim walked from his house to the junction which is 1.5 km from his house. Then he turned back and stopped at Pak Dins stall which is 0.5 km from his house.(a) Berapakah sesaran Rahim dari rumahnya/What is Rahims displacement from his house (i) apabila dia sampai di simpang?/when he reached the junction?

(b) Selepas bersarapan pagi, Rahim berjalan pulang ke rumahnya. Apabila dia sampai di rumahnya,After breakfast, Rahim walked back to his house. When he reached home,

Contoh/ExampleRumah RahimRahims house

0.5 km 1.5 km

Warung Pak DinPak Dins stall

B O

Definisi jarak dan sesaranDefine distance and displacement

2.1 MENGANALISIS GERAKAN LINEARANALYSING LINEAR MOTION

Utara/North

02 FIZ Form 4 Ch2 A 2F.indd 22 9/10/13 4:26 PM

(ii) apabila dia berada di warung Pak Din?/when he was at Pak Dins stall?

(i) berapakah jumlah jarak yang dilalui oleh Rahim?/what was the total distance travelled by Rahim?

(ii) berapakah jumlah sesaran Rahim dari rumahnya?/what was Rahims total displacement from his house?

1

1 Laju ialah kadar perubahan jarak Speed is the rate of change of distance

Laju, v = Jarak dilaluiMasa yang diambil Speed, v = Distance travelled

Time taken

Kuantiti/Quantity: Skalar/Scalar Unit SI/SI unit: m s1

2 Halaju ialah kadar perubahan sesaran Velocity is the rate of change of displacement

Halaju, v = SesaranMasa yang diambil Velocity, v = Displacement

Time taken

Kuantiti/Quantity: Vektor/Vector Unit SI/SI unit: m s1

3 Arah halaju adalah arah sesaran. Direction of velocity is the direction of the displacement.

Definisi Laju dan HalajuDefine Speed and Velocity

Laju purata,v =

Jumlah jarak dilalui, sJumlah masa yang diambil, t

Average speed,v =

Total distance travelled, sTotal time taken, t

Halaju purata:v =

Sesaran, sJumlah masa yang diambil, t

Average velocity:v =

Displacement, sTotal time taken, t

Laju sekata Laju yang magnitudnya kekal sama tanpa mempertimbangkan arahnya.

Uniform speed Speed that remains the same in magnitude regardless of its direction.

Halaju sekata Halaju yang magnitud dan arahnya kekal sama.

Uniform velocity Velocity that remains the same in magnitude and direction .

Suatu objek mempunyai halaju tak sekata jika:An object has a non-uniform velocity if:(a) arah gerakan berubah atau gerakan tidak linear.

the direction of motion changes or the motion is not linear.(b) magnitud halaju berubah.

the magnitude of its velocity changes.


2

Sebuah kapal terbang menuju ke utara selama 1 jam dengan halaju300 km j1. Kemudian, kapal terbang bergerak ke timur selama 1 jam dengan halaju 400 km j1. An aeroplane flies towards the north for 1 hour with a velocity of 300 km h1. Then, the plane moves to the east for 1 hour with a velocity of 400 km h1. (a) Berapakah laju purata kapal terbang itu? What is the average speed of the plane?

400 km j1

300 km j1

A

O

B

Contoh/Example 1

Bacaan meter had laju bagi sebuah kereta yang bergerak ke arah utara menunjukkan 80 km j1. Sebuah kereta yang lain bergerak pada 80 km j1 menuju ke selatan. Adakah kelajuan kedua-dua kereta itu sama? Adakah halaju kedua-dua kereta itu sama? Terangkan jawapan anda.The speedometer reading for a car travelling north shows 80 km h1. Another car is travelling at 80 km h1 towards the south. Is the speed of both cars the same? Is the velocity of both cars the same? Explain your answer.

Contoh/Example 2


(b) Berapakah halaju purata kapal terbang itu?/What is the average velocity of the plane?

3

Pecutan sifar bermaksud suatu objek berada dalam keadaan pegun atau bergerak pada halaju malar, a = 0 Zero acceleration means an object is at rest or is moving at a constant velocity, a = 0

a positif (pecutan): Halaju suatu objek bertambah dari halaju awal, u, kepada halaju akhir, v yang lebih tinggi.

positive a (acceleration): The velocity of an object increases from an initial velocity, u, to a higher final velocity, v.

a negatif (nyahpecutan): Halaju suatu objek berkurang dari halaju awal, u, kepada halaju akhir, v yang lebih rendah.

negative a (deceleration): The velocity of an object decreases from an initial velocity, u, to a lower final velocity, v.

Seorang penunggang basikal bermula dari keadaan rehat dan menambahkan halajunya pada kadar seragam sehingga dia mencapai halaju 4.0 m s1 dalam 5.0 s. Berapakah purata pecutannya?A cyclist starts from rest and increases his velocity at a constant rate until he reaches a velocity of 4.0 m s1 in 5.0 s.What is his average acceleration?Halaju awal/Initial velocity = 0Halaju akhir/Final velocity = 4.0 m s1 Masa yang diambil/Time taken = 5.0 s

Contoh/Example

pecutan, a = v u

t acceleration, a = v u

t

a = (4.0 0) m s15.0 s

= 0.8 m s2

1 Pecutan, a, didefinisikan sebagai .Acceleration, a, is defined as .

2 Formula dan Unit SI:/Formula and SI unit:

Pecutan, a = Perubahan halaju

Masa yang diambil Acceleration, a = Change in velocity

Time taken

=

Halaju akhir, v Halaju awal, uMasa yang diambil, t =

Final velocity, v Initial velocity, uTime taken, t

=

v u

t =

v u

t

Unit SI/SI unit:

Definisi pecutan dan nyahpecutanDefinition of acceleration and deceleration


4

Perhatikan gerakan sebuah kereta dalam Rajah (a) dan Rajah (b) yang merupakan gambar stroboskop.Observe the motion of the car in Diagram (a) and Diagram (b) which are stroboscopic pictures.

(a) (b) Rajah (a)/Diagram (a) Rajah (b)/Diagram (b)

(i) Huraikan perubahan halaju sebuah kereta dalam Rajah (a). Adakah kereta memecut atau menyahpecut? Describe the changes in velocity of the car in Diagram (a). Is the car accelerating or decelerating?

(ii) Huraikan perubahan halaju sebuah kereta dalam Rajah (b). Adakah kereta memecut atau menyahpecut? Describe the changes in velocity of the car in Diagram (b). Is the car accelerating or decelerating?

Contoh/Example

1 Lengkapkan jadual berikut untuk membuat perbandingan antara dua istilah yang diberi.Complete the following tables to do comparisons between the terms given.

Jarak/Distance Sesaran/Displacement Laju/Speed Halaju/VelocityJarak ialah jumlah panjang laluan yang dilalui dari satu lokasi kesatu lokasi yang lain.Total path length travelled from one location to another.

Sesaran ialah jarak dalam arah tertentu.Displacment is the distance in a specified direction.

Laju ialah kadar perubahan jarak.Speed is the rate of change of distance.

Halaju ialah kadar perubahan sesaran.Velocity is the rate of change of displacement.

Kuantiti asasBase quantity

Kuantiti asasBase quantity

Quantiti terbitanDerived quantity

Quantiti terbitanDerived quantity

Kuantiti skalar Scalar quantity

Kuantiti vektorVector quantity

Kuantiti skalarScalar quantity

Kuantiti vektorVector quantity

2 Seorang budak berjalan sepanjang laluan PQ./A boy walks along path PQ. Cari/Find (a) jumlah jarak dilalui./total distance travelled.

Latihan/Exercises

5 m

7 m

10 m

10 m

10 m

PQ


(b) sesaran./displacement.

5

Hubung kait Sesaran, Halaju, Pecutan dan MasaRelating Displacement, Velocity, Acceleration and Time

Jangka masa detik:/Ticker timer: Iadisambungkebekalankuasa 50 Hz. Apabila dihidupkan, bilah pengetuk akan

bergetar 50 kali sesaat. It is connected to an supply

of 50 Hz. When it is switched on, the iron strip will vibrate 50 times per second.

Masadiambiluntukmembuat50titikpadapitadetik

ialah 1 saat. Jadi, selang masa antara dua titik yang berturutan ialah 150 s = 0.02 s. The time taken to make 50 dots on the ticker tape is 1 second. Hence, the time interval between 2 consecutive

dots is 150

s = 0.02 s.

1detikdidefinisikansebagai .

1 tick is defined as .

6 12 V a.c.

Jangka masa detikTicker timerTroli dinamik

Dynamic trolley

Aktiviti 1 Kaedah pengiraanActivity 1 Method of calculation

Menyiasat gerakan dalam makmal iaitu menentukan jarak / sesaran, kelajuan / halaju, masa dan pecutan /nyahpecutanTo investigate motion in laboratory to determine distance / displacement, speed / velocity, time and acceleration /deceleration

10 ticks/detik

8.0 cm BA

3 Isikan tempat kosong/Fill in the blanks: (a) Laju malar 10 m s1 Jarak sejauh 10 m dilalui setiap saat

A constant speed of 10 m s1 A distance of 10 m is travelled every second (b) Halaju malar 10 m s1 Sesaran sejauh 10 m yang dilalui setiap saat dalam arah

bertentanganA constant velocity of 10 m s1 A displacement of 10 m is travelled every second in the opposite direction.

(c) Pecutan malar 4 m s2 Halaju meningkat dengan 4 m s1 setiap saat A constant acceleration of 4 m s2 Velocity increases by 4 m s1 every second

(d) Nyahpecutan malar 4 m s2 Halaju berkurang dengan 4 m s1 setiap saat A constant deceleration of 4 m s2 Velocity decreases by 4 m s1 every second


6

LANGKAH 1: Menentukan masa diambil untuk 1 detik.STEP 1: Determination of time taken for 1 tick.

(a) Masa yang diambil untuk 50 detik = 1 saat(b) Masa yang diambil untuk 1 detik = s(c) Masa yang diambil dari A ke B = detik = s

(a) Time taken for 50 ticks = 1 second(b) Time taken for 1 tick = s(c) Time taken from A to B = ticks = s

LANGKAH 2: Menentukan sesaranSTEP 2: Determination of displacementSesaran suatu objek ditentukan dengan mengukur panjang pita detik yang ditarik melalui jangka masa detikThe displacement of the object is determined by measuring the length of the ticker tape that is pulled through the ticker time

Sesaran A ke B = cm/Displacement from A to B = cmLANGKAH 3: Menentukan halajuSTEP 3: Determination of velocity

LANGKAH 4: Menentukan pecutanSTEP 4: Determination of acceleration

1.5 cm 3.5 cm 5.5 cm 7.5 cm

A B C D E

Pecutan/Acceleration,


Dari jalur pertama: Halaju pertama, u, pada AB/From the first strip: Initial velocity, u, at AB

Dari jalur terakhir: Halaju terakhir, v, pada DE/From the final strip: Final velocity, v, at DE

Selang masa, bagi perubahan halaju, t/The time interval, t, for the change in the velocity

7

1

Arah pergerakanDirection of motion

0.2 cm 1.4 cm

Berdasarkan rajah di atas, hitungkan pecutan objek itu.Based on the diagram above, calculate the acceleration of the object.

2BA C D E2.0 cm 4.0 cm 6.0 cm 8.0 cm

Arah pergerakanDirection of motion

Rajah di atas menunjukkan suatu pita detik yang mengandungi 5 detik untuk setiap selang AB-BC-CD dan DE. Hitungkan pecutan objek itu.The diagram above shows a ticker tape contains 5 ticks for every interval AB-BC-CD and DE. Calculate the acceleration of the object.

3 Rajah di sebelah menunjukkan carta pita detik bagi sebuah troli yang bergerak. Frekuensi bagi jangka masa detik ialah 50 Hz. Setiap jalur pita merupakan panjang 10 detik. The diagram on the right shows a ticker tape chart for a moving trolley. The frequency of the ticker-timer used is50 Hz. Each strip of the tape is a 10-ticks length.

(a) Berapakah selang masa antara dua titik?What is the time interval between two dots?

(b) Berapakah selang masa untuk satu jalur?What is the time interval for one strip?

(c) Berapakah halaju awal?What is the initial velocity?

(e) Berapakah selang masa yang diambil untuk berubah dari halaju awal kepada halaju akhirnya?What is the time interval to change from its initial velocity to its final velocity?

12.0

Panjang 10 detik/cm10-tick length/cm

0

2.0

4.0

6.0

8.0

10.0

Detik/Ticks

Jalur pitaStrip of the tape


Latihan

Penyelesaian/Solution Penyelesaian/Solution

(d) Berapakah halaju akhir?/What is the final velocity?

(f) Berapakah pecutan objek itu?/What is the acceleration of the object?

000000800000088

Aktiviti 2 Untuk mengenal pasti jenis gerakanActivity 2 To identify the types of motion

PITA DETIK DAN CARTATICKER TAPE AND CHARTS

Panjang/Length (cm)

Arah gerakanDirectionof motion

Detik/Ticks

Jenis gerakan: Type of motion:

Jarak dilalui antara dua titik berturutan:Distance between two consecutive dots:

1 2 3 4 5 6

4.0

0.5

1.2

1.9

2.6

3.3

Panjang/Length (cm)


Detik/Ticks

Jarakantaraduatitikberturutan secara seragam.The distance between two consecutive dots

Halajuobjekitu secara seragam. The velocity of the object

uniformly. Objekitubergerakpada seragam. The object moves at a uniform .

Panjang/Length (cm)


Detik/Ticks

Jarakantaraduatitikberturutan secara seragam.

The distance between two consecutive dots

Halajuobjekitu secara seragam. The velocity of the object

uniformly. Objekitubergerakpada seragam. The object moves at a uniform .

(i)

(ii)

(iii)


Selesaikan masalah pada gerakan linear dengan pecutan seragamSolve problems on linear motion with uniform acceleration

(1) v = u + at (2) s = u + v2 t (3) s = ut + at2 (4) v2 = u2 + 2as

di mana/where:s: sesaran/displacementu: halaju awal/initial velocity

v: halaju akhir/final velocitya: pecutan/acceleration

t: masa/time

9

uniformly.

uniformly.

1 Sebuah kereta memecut dari keadaan rehat ke 25 m s1 dalam 4 s. Cari pecutan kereta itu.A car accelerates from rest to 25 m s1

2 Sebuah kereta memecut dari keadaan rehat pada 3 m s2 sepanjang suatu jalan lurus. Berapakah sesaran yang

dilalui oleh kereta itu selepas 4 s?A car accelerates from rest at 3 m s2 along a straight road. How far has the car travelled after 4 s?

3 Sebuah kereta bergerak dengan halaju 20 m s1 sepanjang jalan lurus. Pemandu itu menekan brek selama 5 s. Ia

menyebabkan nyahpecutan 3 m s2, berapakah halaju akhir kereta itu?A car is travelling at 20 m s1 along a straight road. The driver brakes for 5 s. This causes a deceleration of 3 m s2. What is the final velocity of the car?

4 Sebuah kereta bergerak dengan halaju malar 40 m s1. Pemandu ternampak suatu penghalang di hadapannya dan dia segera menekan brek. Dia dapat memberhentikan keretanya dalam masa 8 s. Jarak

antara penghalang itu dari kereta apabila pemandu ternampak penghalang itu ialah 180 m. Berapakah jarak penghalang itu dari kereta selepas ia berhenti?A car was moving at a constant velocity of 40 m s1. The driver saw an obstacle in front and he immediately stepped on the brake pedal. He managed to stop the car in 8 s. The distance of the obstacle from the car when the driver spotted it was 180 m. How far was the obstacle from the car after it stopped?

Latihan/Exercises

t = 4 s

0 m s1

Sesaran / Displacement

a = 3 m s2

t = 5 s

20 m s1 v

a = 3 m s2


10

in 4 s. Find the acceleration of the car.

Penyelesaian/Solution

2.2 MENGANALISIS GRAF GERAKANANALYSING MOTION GRAPH

Daripada graf gerakan, anda akan memahami:From motion graphs, you will understand:(i) berapa jauh yang telah dilalui oleh sesuatu objek (jarak, sesaran) how far an object has travelled (distance, displacement)(ii) berapa cepat ia bergerak (laju, halaju) how fast it is moving (speed, velocity)(iii) perubahan halaju terhadap masa (pecutan / nyahpecutan) change of velocity with time (acceleration / deceleration)

Lakar dan tafsir graf sesaran-masaPlot and interpret displacement-time graph

Rajah di sebelah kanan menunjukkan gerakan sebuah kereta pada masa yang berlainan.The diagram on the right shows the motion of a car with respect to time.(a) Lakarkan graf sesaran-masa kereta itu. Plot a displacement-time graph for the car.(b) Hitungkan kecerunan graf. Calculate the gradient of the graph.

(c) Apakah unit bagi kecerunan? What is the unit of this gradient?

(d) Apakah kuantiti fizik yang ditunjukkan oleh unit ini?What is the physical quantity shown by this unit?

0 mKedudukan:Position

10 m 20 m 30 m 40 m 50 m

t = 0 s 1 s 2 s 3 s 4 s 5 s

00

10

20

30

40

50

1 2 3

Masa/Time (s)

Kedu

duka

n/Po

sitio

n (m

)

4 5

Kecerunan graf = halajuThe gradient = velocityof the graph

Membuat kesimpulan daripada bentuk graf sesaran-masaDeduction from the shape of a displacement-time graph

Objek pada keadaan rehat

Object at rest

Sesaran/Displacement,s/m

t/s0

Objekberadadalamkeadaan kerana ia berada pada pada bila-bila masa.The object is at because it is at the at any time.

Halaju = kecerunan grafVelocity = gradient of the graph = m s1

Graf sesaran-masaDisplacement-time graph


11

Objek bergerak dengan halaju

malarObject moving at constant velocity

t/s0

20

5


Objekbergerakpadahalaju kerana sesaran bertambah secara seragam dalam setiap saat.

Object travels at velocity because displacement increases constantly in every second.

Garislurusgrafmempunyaikecerunanyang .

The straight line of the graph has a gradient. Halaju =kecerunan

Velocity = gradient

= m s1

Objek bergerak dengan pecutan

Object moving with acceleration

t/s0


Objekbergerakdenganpecutankeranakadar

perubahan sesaran . Object moves with acceleratiom because the rate of change

of displacement is . Kecerunanlengkungan , dan ini

menunjukkan bertambah. The gradient of the curve is showing that

the is increasing.

Objekmengalami .

The object experiences .

Menentukan jarak, sesaran dan halaju dari graf sesaran-masaDetermine distance, displacement and velocity from the displacement-time graph

Rajah di bawah menunjukkan graf sesaran-masa bagi suatu objek.The diagram below shows a displacement-time graph of an object.Berdasarkan graf,Based on the graph, (a) Hitungkan halaju objek antara calculate the velocity of the object between (i) A dan/and B (ii) B dan/and C (iii) C dan/and D

(b) Gambarkan gerakan objek itu antaraDescribe the motion of the object between

(i) A dan B: (ii) B dan C: A and B: B and C:

C and D:

Sesaran/mDisplacement / m

B C

DA0

20

10 30 35Masa/sTime / s


12

(iii) C dan D:

Lakar dan tafsir graf halaju-masaPlot and interpret velocity-time graph

Rajah menunjukkan kereta bergerak dari rehat dalam suatu garis lurus.The diagram shows the car move from rest in a straight line.(a) Lakarkan graf halaju-masa bagi

kereta ini. Plot the velocity-time graph for the car.(b) Hitungkan kecerunan graf. Calculate the gradient of the graph.

2

(c) Apakah unit bagi kecerunan ini? What is the unit of this gradient?

(d) Apakah kuantiti fizik yang ditunjukkan oleh unit ini?What is the physical quantity shown by this unit?

t = 0 s 1 s 2 s 3 s 4 s 5 s

0 m s1 2 m s1 4 m s1 6 m s1 8 m s1 10 m s1Halaju:Velocity

Graf halaju-masaVelocity-time graph Kecerunangraf=pecutanataunyahpecutan The gradient of graph = acceleration or deceleration Luasdibawahgraf=sesaran The area under the graph = displacement

00

2

4

6

8

10

1 2 3 4 5

Masa/Time(s)

Halaju/Velocity(m s1)

Graf halaju-masaVelocity-time graph

(d) Hitungkan/Calculate (i) laju purata (ii) halaju purata gerakan zarah itu. the average speed the average velocity of the moving particle.


13

(c) Cari/Find (i) jumlah jarak/total distance (ii) jumlah sesaran/total displacement

Membuat kesimpulan daripada bentuk graf halaju-masaDeduce from the shape of velocity-time graph

ObjekberadadalamkeadaanrehatObject at rest

Objekbergerakdenganhalaju malar

Object moves with constant velocity

ObjekbergerakdenganpecutanmalarObject moving with constant

acceleration

Objekbergerakdengannyahpecutan malar

Object moves with constant deceleration

Nota/Notes: Dalamanalisisgerakanlinear,jikahalajusuatuzarahadalahsifar,inibermaknazarahituberhentibergerak. In linear motion analysis, if the velocity of a particle is zero, it means that the particle has stopped moving. Jikahalajuzarahitumenjadinegatif,makazarahitubergerakdalamarahbertentangandenganarahgerakanawalnya. If the velocity of the particle becomes negative, then the particle is moving opposite to its earlier direction of motion.

Kecerunan=pecutan=

Luasdibawahgraf=sesaran=

.

Object is at rest .

Kecerunan/Gradient = pecutan/acceleration =

Luasdibawahgraf=sesaran=

m

Displacement travelled = 20 m

Objekbergerakdenganhalaju malar

Object moves with constant velocity

Kecerunan/Gradient = malar/constant = 18 m s1

3 s = 6 m s2

Pecutan/Acceleration = 6 m s2

Luasdibawahgraf/Area under the graph

=

12 (18 m s

1)(3 s) = 27 m

Sesarandilalui/Displacement travelled = 27 m Objekbergerakdenganpecutan malar

Object moves with constant acceleration

Kecerunangrafadalah malar dan negatif

The gradient of the graph is constant and negative

Objekitubergerakdengan nyahpecutan seragam The object is moving with uniform deceleration

v/m s-1

t/s0

v/m s-1

t/s0 2

10

v/m s-1

t/s0

18

3

v

t0


14

Gradient = acceleration =

Area under the graph = displacement =

Objek berada dalam keadaan

Area under the graph = displacement =

Sesarandilalui=

Menentukan jarak, sesaran, halaju dan pecutan daripada graf halaju-masaDetermine distance, displacement, velocity and acceleration from a velocity-time graph

Berikut menunjukkan graf halaju-masa bagi sebuah kereta. Berdasarkan graf, The following shows the velocity-time graph of a car. Based on the graph,

Halaju/Velocity / m s-1

K

L M

N

OJ0

20

10

10

10 20 30 4035 45 50Masa/sTime / s

(a) hitungkan pecutan kereta itu bagi calculate the acceleration of the car for (i) JK a = 20 m s

1

10 s = 2 m s2

(ii) KL a = (20 10) m s1(20 10) s = 1 m s

2

(iii) LM a = 0

(iv) MN a = 20 m s

1

10 s = 2 m s2

(b) Nyatakan jenis gerakan kereta itu bagi State the types of motion of the car for (i) JK : pecutan malar (ii) KL : nyahpecutan malar (tetap)

constant acceleration

constant deceleration

(iii) LM : halaju tetap (iv) MN : nyahpecutan tetap

constant velocity

constant deceleration

(c) Hitungkan jumlah sesaran yang dilalui oleh kereta itu semasa Calculate the total displacement travelled by the car during (i) gerakan bagi 10 s yang pertama (ii) kereta bergerak dengan halaju seragam the first 10 s of motion the car moves with uniform velocity

Sesaran Displacement

= 12

(20 m s1)(10 s) Sesaran Displacement

= 10 m s1 10 s = 100 m

= 100 m (iii) gerakan bagi 10 s yang terakhir the last 10 s of motion Sesaran / Displacement = 0

(d) Hitungkan / Calculate (i) jumlah jarak bagi keseluruhan perjalanan (ii) jumlah sesaran bagi keseluruhan perjalanan. the total distance for the whole journey the total displacement for the whole journey. Sesaran / Displacement Sesaran / Displacement

= (100 + 150 + 100 + 25 + 50) m = 425 m 50 m= 425 m = 375 m

(e) Hitungkan / Calculate (i) laju purata / the average speed (ii) halaju purata / the average velocity Laju purata / Average speed Halaju purata / Average velocity

= 425 m45 s = 9.44 m s

1 =

375 m45 s = 8.33 m s

1


15

Menyelesaikan masalah gerakan linear dengan pecutan seragamSolve problems on linear motion with uniform acceleration

P Q

R

S

O0

20

10

10

2 4 6 8 t/s


1 Hitungkan/Calculate (i) halaju bagi OP, QR dan RS

velocity of OP, QR and RS (ii) sesaran/displacement

Penyelesaian/Solution: (i) OP: halaju/velocity = 20 m

2 s = 10 m s1

QR: halaju/velocity = 20 m2 s

= 10 m s1

RS: halaju/velocity = 10 m1 s

= 10 m s1

(ii) s = (20 + 0 20 10)m = 10 m

2 Hitungkan/Calculate (i) pecutan bagi OA dan BC acceleration of OA and BC (ii) jumlah sesaran/total displacement Penyelesaian/Solution: (i) OA: pecutan

acceleration =

10 m s110 s

= 1 m s2

BC: pecutan acceleration

= 10 m s1

5 s = 2 m s2

(ii) Jumlah sesaran Total displacement

= 12

(25 + 10)s (10 m s1)

= 175 m

Halaju / m s-1Velocity / m s-1

A B

CO0

10

5

5 10 15 20 25t/s

Kesimpulan/Conclusion 1 Kecerunan graf s melawan t memberi halaju suatu objek.

Gradient of the graph s against t gives the velocity of an object. 2 Kecerunan graf v melawan t memberi pecutan suatu objek.

Gradient of the graph v against t gives the acceleration of an object. 3 Luas di bawah graf v melawan t memberi sesaran yang dilalui oleh objek.

Area under the graph v against t gives the displacement travelled by the object.


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Ringkasan bagi bentuk graf gerakanSummary of shapes of motion graphs

GrafGraph

s melawan ts against t

v melawan tv against t

a melawan ta against t

Halaju sifarZero velocity

s

t0

v

t0

Halaju negatifNegative velocity

s

t0

v

t0

Halaju seragamUniform velocity

s

t0

v

t0

a

t0

Pecutan seragamUniform acceleration

s

t0

v

t0

a

t0

Nyahpecutan seragamUniform deceleration

s

t0

v

t0

a

0 t


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bab 2_ 2.2 latihan.pdf

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