Chapter 3 Revision

CHAPTER/TAJUK: 3 (GRAVITATION/KEGRAVITIAN)

Formula:

1

Section A
Bahagian A

1. Diagram 1 shows two objects with masses m1 and m2 respectively separated at distance, r.
The gravitational force, F acting on the objects can be explained by a law.
Rajah 1 menunjukkan dua objek masing-masing berjisim m1 dan m2 dipisahkan dengan jarak,
r. Daya graviti, F yang bertindak pada objek tersebut diterangkan oleh satu hukum.

FF m2
m1

r
Diagram / Rajah 1
(a) State the law involved.
Nyatakan hukum yang terlibat.

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) Underline the correct relationship di the brackets.

Based on the law, the gravitational force acting on the objects is (inversely proportional
/ directly proportional) with the product of m1 and m2 and ((inversely proportional /
directly proportional) with r2.
Gariskan hubungan yang betul di dalam kurungan.

Berdasarkan hukum tersebut, daya graviti yang bertindak pada objek adalah (berkadar
terus / berkadar songsang) dengan hasil darab jisim m1 dan m2 serta (berkadar terus /
berkadar songsang) dengan r2.

[2 marks / 2 markah]
(c) What will happen with gravitational force, F is distance, r is increased?
Apakah yang berlaku pada daya graviti, F jika jarak, r bertambah?

…………………………………………………………………………………………….
[1 mark / 1 markah]

2

2. Diagram 2 shows gravitational force, F acting on a boy and a girl of mass 70 kg and 53 kg
respectively which separated at distance, r = 1.0 m.
Rajah 2 menunjukkan daya graviti, F yang bertindak pada seorang lelaki dan perempuan
berjisim masing-masing 70 kg dan 53 kg yang dipisahkan pada jarak, r = 1.0 m.

m1 = 70 kg r = 1.0 m m2 = 53 kg
FF

Diagram / Rajah 2

(a) Define gravitational force.
Definisikan daya graviti.

…………………………………………………………………………………………….

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) Gravitational force, F can be calculated by using formula:
Daya graviti boleh dihitung dengan menggunakan formula:

Where G is gravitational constant.
Dimana G adalah pemalar kegravitian.
(i) State the SI unit of G.

Nyatakan unit SI bagi G.

……………………………………………………………………………………..
[1 mark / 1 markah]

(ii) Calculate the gravitational force, F.
Hitung daya graviti, F

[2 marks / 2 markah]
(c) Why the boy and the girl did not experiences the effect of gravitational force toward

each other?
Mengapakah lelaki dan perempuan tersebut tidak merasai kesan daya graviti antara
satu sama lain?

…………………………………………………………………………………………….
[1 mark / 1 markah]

3

3. A satellite experiences acceleration due to gravity, g = 9.81 m s-2 on the surface of Earth
before launching.
Sebuah satelit mengalami pecutan graviti, g = 9.81 m s-2 di permukaan bumi sebelum
dilancarkan
Given / Diberi:
Radius of Earth / Jejari bumi, R = 6.37 106 m ,
Gravitational constant / Pemalar kegravitian, G = 6.67 10−11 Nm−2kg −2

(a) Calculate the mass of Earth.
Hitung jisim bumi.

[2 marks / 2 markah]
(b) If the satellite launched at height 480 000 m from the surface of Earth, calculate

acceleration due to gravity, g experienced by the satellite.
Jika satelit tersebut dilancarkan ke ketinggian 480 000 m dari permukaan bumi, hitung
pecutan graviti, g yang dialami oleh satelit.

[2 marks / 2 markah]

(c) If another satellite has twice mass launched to the same height, state the change in its
acceleration due to gravity, g. Mark [ √ ]

Jika sebuah satelit yang berjisim dua kali ganda dilancarkan ke ketinggian yang sama,
nyatakan perubahan pecutan graviti yang dialaminya. Tandakan [ √ ]

Increasing Decreasing Same
Bertambah Berkurang Sama

[1 mark / 1 markah]
(d) Based on acceleration due to graviti, g against distance, r graph, sketch the shape of

graph after the satellite leaving the surface of Earth. (After radius of Earth, R)
Berdasarkan graf pecutan graviti, g melawan jarak, r dibawah, lakarkan bentuk graf
apabila satelit meninggalkan permukaan bumi. (Selepas jejari bumi, R)

g

0R r
[1 mark / 1 markah]

4

4. Diagram 4 shows a satellite orbiting the earth with a linear speed, v at height, h = 480 000 m
form the surface of the earth.
Rajah 4 menunjukkan sebuah satelit mengorbit bumi dengan suatu laju linear, v pada
ketinggian, h = 480 000 m daripada permukaan bumi.

Earth h v
Bumi
Satellite
Satelit

M = 5.98 1024 kg

Diagram / Rajah 4
Radius of the Earth / Jejari bumi, R = 6.37 106 m , G = 6.67 10−11 Nm2kg −2

(a) What is the meaning of speed?
Apakah yang dimaksudkan dengan laju?

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) Calculate the linear speed of satellite.
Hitung laju linear satelit.

[2 marks / 2 markah]

(c) Calculate centripetal acceleration of satellite.
Hitung pecutan memusat bagi satelit.

[2 marks / 2 markah]
(d) What will happen to the satellite if its linear speed is decreasing?

Apakah yang akan terjadi kepada satelit jika laju linearnya berkurangan?
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….

[2 marks / 2 markah]

5

5. Diagram 5 shows two satellites S1and S2 of the same mass evolve around the earth.
Rajah 5 menunjukkan dua satelit S1dan S2 berjisim sama mengelilingi bumi.

Orbit of satellite
Orbit satelit

Earth r1 S1
Bumi r2
m1 = 4 00 kg

S2 m 2 = 400 kg
Diagram / Rajah 5

(a) Mass is a ……………………. quantity. [1 mark / 1 markah]
Jisim adalah kuantiti ……………………………

(b) Based on Diagram 5,
Berdasarkan Rajah 5,
(i) Compare the mass of satellite m1and m2 .
Bandingkan jisim satelit m1dan m2

……………………………………………………………………………………..
[1 mark / 1 markah]

(ii) Compare the orbital radius of satellite r1and r2 .
Bandingkan jejari orbit bagi satelit r1 dan r2.

……………………………………………………………………………………..
[1 mark / 1 markah]

(iii) Compare the orbital period of satellite S1and S2 .
Bandingkan tempoh orbit bagi satelit S1dan S2 .

……………………………………………………………………………………..
[1 mark / 1 markah]

(iv) State the relationship between orbital radius and orbital period.
Nyatakan hubungan antara jejari orbit dan tempoh orbit.

……………………………………………………………………………………..
[1 mark / 1 markah]

(c) State the law involved in 5(b)(iii).
Nyatakan hukum yang terlibat dalam 5(b)(iii).

…………………………………………………………………………………………….
[1 mark / 1 markah]

6

(d) (i) What happen to the orbital period if the mass is satellite S1is increased?
Apakah yang terjadi kepada tempoh orbit jika jisim satellite S1ditambah?

……………………………………………………………………………………..
[1 mark / 1 markah]

(ii) Explain your answer in d(i).
Terangkan jawapan anda di d(i).

……………………………………………………………………………………..
[1 mark / 1 markah]

6. Diagram 6 shows a planet evolves the sun. The time taken for the planet to travel from A to B
is equal from C to D.
Rajah 6 menunjukkan sebuah planet mengelilingi matahari. Masa yang diambil untuk planet
bergerak dari A ke B adalah sama dari C ke D.

B C
Sun
Matahari

F D
A

Planet

Diagram / Rajah 6

(a) State the shape of orbit.
Nyatakan bentuk orbit.

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) Based on Diagram 6,
Berdasarkan Rajah 6,
(i) Compare the area covered by the planet at region FAB and FCD.
Bandingkan luas yang dicakupi oleh planet di kawasan FAB dan FCD.

……………………………………………………………………………………..
[1 mark / 1 markah]

(ii) Compare the arc length of orbit AB and CD.
Bandingkan panjang lengkok orbit bagi AB dan CD.

……………………………………………………………………………………..
[1 mark / 1 markah]

(iii) Compare the linear speed of planet at AB and CD.
Bandingkan laju linear A ke B dan C ke D.

……………………………………………………………………………………..
[1 mark / 1 markah]

7

(iv) State the relationship between the time taken and area covered at both region.
Nyatakan hubungan antara masa yang diambil dengan luas yang dicakupi bagi
kedua-dua kawasan.
……………………………………………………………………………………..
[1 mark / 1 markah]

(c) State the law involved to explain 6(b)(iv).
Nyatakan hukum yang terlibat untuk menerangkan 6(b)(iv)
…………………………………………………………………………………………….
[1 mark / 1 markah]

(d) Calculate the orbital period of the planet if the average distance from the center of the
Sun to the orbit is 1.51011m . Mass of Sun = 1.99 1030 kg , G = 6.6710−11 Nm2kg −2
Hitung tempoh orbit bagi planet jika jarak purata dari pusat matahari ke orbit adalah
1.5 1011m . Jisim matahari = 1.99 1030 kg , G = 6.67 10−11 Nm2kg −2 .

[2 marks / 2 markah]

8

7. Figure 7 shows an athlete in hammer throw is rotating the hammer in a circle before releasing
it. The linear speed of the hammer is 20 m s−1 .
Rajah 7 menunjukkan seorang atlet acara lontar tukul besi yang sedang memutarkan tukul
besi dalam suatu bulatan sebelum melepaskannya. Laju linear bagi tukul adalah 20 m s−1 .

Hammer
Tukul

mass = 7.2 kg
jisim

Diagram / Rajah 7
(a) State the type of force that acting towards the circle.

Namakan jenis daya yang bertindak ke arah pusat bulatan.

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) Calculate the force that you stated in 7(a).
Hitung daya yang anda nyatakan di 7(a).

[2 marks / 2 markah]

(c) State the direction of the hammer after releasing it.
Nyatakan arah tukul selepas dilepaskan.

…………………………………………………………………………………………….
[1 mark / 1 markah]

(d) As an athlete who wants to win the event, some of the techniques should be done.
Explain the techniques clearly. Give reasons for your answer.
Sebagai seorang atlet yang ingin menang dalam acara tersebut, beberapa teknik harus
dilakukan. Nyatakan dengan jelas teknik tersebut. Berikan alasan bagi jawapan anda.
(i) Linear speed of the hammer
Laju linear bagi hammer

……………………………………………………………………………………..
Reason / Alasan:

……………………………………………………………………………………..

[2 marks / 2 markah]

9

(ii) Time taken for rotation of hammer
Masa untuk putaran untuk tukul besi
……………………………………………………………………………………..
Reason / Alasan:
……………………………………………………………………………………..
[2 marks / 2 markah]
(iii) Angle of projection of hammer
Sudut lontaran tukul besi
……………………………………………………………………………………..
Reason / Alasan:
……………………………………………………………………………………..
[2 marks / 2 markah]

10

8. Diagram 8 shows a conveyor rocket to send space shuttle to outer space.
Rajah 8 menunjukkan roket penghantar pesawat angkasa lepas.
External fuel tank
Tangki bahan api luaran

Rocket boosters
Penggalak roket

Space shuttle
Pesawat angkasa

Diagram / Rajah 8
(a) State the change in energy when conveyor rocket move from the surface of the Earth to

the Earth’s atmosphere.
Nyatakan perubahan tenaga apabila roket penghantar bergerak dari permukaan bumi
ke ruang atmosfera bumi.

…………………………………………………………………………………………….
[1 mark / 1 markah]

(b) The rocket must achieves escape velocity, v in order to reach the outer space.
Roket tersebut harus mencapai halaju lepas, v untuk sampai ke angkasa lepas.
(i) What is the meaning of escape velocity?
Apakah maksud bagi halaju lepas?

……………………………………………………………………………………..

[1 mark / 1 markah]

(ii) Calculate the escape velocity, v of the rocket.
Hitung halaju lepas, v bagi roket.

[Mass of Earth / Jisim bumi, M = 5.97 1024 kg ,

Radius of earth / Jejari bumi, R = 6.37 106 m , G = 6.67 10−11 Nm2kg −2 ]

[2 marks / 2 markah]
(iii) Calculate the kinetic energy of rocket during escape to the outer space. The mass

of rocket is 131 000 kg.
Hitung tenaga kinetik roket semasa terlepas ke luar angkasa. Jisim roket adalah
131 000 kg.

[2 marks / 2 markah]

11

(c) A high efficiency rocket must be built before it is launched. Table 1 shows three

different types of rocket P, Q and R.

Roket yang mempunyai kecekapan yang tinggi harus dibina sebelum dilancarkan.

Jadual 1 menunjukkan tiga jenis roket P, Q dan R.

Rocket External fuel tank Number of rocket boosters Shape of rocket

Roket Tangki bahan api luar Bilangan roket penggalak Bentuk roket

P Have no tank 2 Aerodynamic
Tidak mempunyai tangki Aerodinamik

Q Have tank 2 Aerodynamic
Mempunyai tangki Aerodinamik

R Have tank 1 Aerofoil
Mempunyai tangki Aerofil

Table / Jadual 1

Based on Table 1, state the suitable characteristics of rocket. Give one reason for

suitability of each characteristic.

Berdasarkan Jadual 1, nyatakan ciri yang sesuai bagi roket. Beri satu sebab bagi

kesesuaian setiap ciri tersebut.

(i) External fuel tank / Tangki bahan api luar

……………………………………………………………………………………..
Reason / Sebab

……………………………………………………………………………………..
[2 marks / 2 markah]

(ii) Number of rocket boosters / Bilangan roket penggalak

……………………………………………………………………………………..
Reason / Sebab

……………………………………………………………………………………..
[2 marks / 2 markah]

(iii) Shape of rocket / Bentuk roket

……………………………………………………………………………………..
Reason / Sebab

……………………………………………………………………………………..
[2 marks / 2 markah]

(d) Based on your answer in 8(c), determine the most suitable roket.
Berdasarkan jawapan anda di 8(c), tentukan roket yang paling sesuai.

…………………………………………………………………………………………….
[1 mark / 1 markah]

12

Section B
Bahagian B
[20 marks / markah]

9. Diagram 10.1 shows a satellite of mass 300 kg orbiting around the earth at height
h = 3105 m from the surface of the earth.
Rajah 10.1 menunjukkan sebuah satelit berjisim 300 kg sedang mengorbit mengelilingi bumi
pada ketinggian h = 3105 m daripada permukaan bumi.

Earth Satellite
Bumi Satelit
h

(a) (i) Diagram / Rajah 10.1
The satellite gained gravitational potential energy. What is the meaning of
gravitational potential energy?
Satelit mempunyai tenaga keupayaan graviti. Apakah maksud bagi tenaga
keupayaan graviti?

[1 mark / 1 markah]

(ii) Calculate the gravitational potential energy oh satelit.
Hitung tenaga keupayaan graviti bagi satelit.
Mass of Earth / Jisim bumi, M = 5.97 1024 kg ,

Radius of earth / Jejari bumi, R = 6.37 106 m ,
Gravitational constant, G = 6.67 10−11 Nm2kg −2

[2 marks / 2 markah]

(iii) If the satellite wants to orbit the earth at period 24 hours (86400 seconds),
determine the new height of the satellite.
Jika satelit tersebut ingin mengelilingi bumi dalam tempoh 24 jam (86400 saat),
tentukan jejari orbit satelit yang baru.
[2 marks / 2 markah]

(b) State the characteristics of geostationary satellite around the earth.
Nyatakan ciri-ciri bagi satelit geopegun yang mengelilingi bumi.
[4 marks / 4 markah]

13

(c) Table 2 shows the characteristics of four telecommunication satellites.
Jadual 2 menunjukkan ciri-ciri bagi empat satelit komunikasi.

Satellite Material of body Colour of body Power source Mass (kg)
Satelit Bahan badan Warna badan Sumber kuasa Jisim
1000
P Low specific heat White Nuclear
capacity Putih energy 200
Q Tenaga
Muatan haba nuklear 300
R tentu rendah
High specific heat Black Kerosene 600
S Hitam Kerosin
capacity
Muatan haba White Solar cells
tentu tinggi Putih Sel-sel solar
High specific heat
Liquid oxygen
capacity
Muatan haba White and hydrogen
tentu tinggi
Low specific heat Putih Cecair oksigen

capacity dan hidrogen
Muatan haba
tentu rendah

Table / Jadual 2

You are assigned to study the characteristics of a satellite that is suitable for
communication. Choose the most suitable satellite and provide the reasons for your
choice.
Anda ditugaskan untuk mengkaji ciri-ciri satelit yang sesuai untuk telekomunikasi. Pilih
satelit yang paling sesuai dan Berikan sebab pilihan anda.

[10 marks / 10 markah]

14

Section C
Bahagian C
[20 marks / markah]

10. Diagram 9.1 shows two rockets P and Q having different weights while moving in the
atmosphere of Earth.
Rajah 9.1 menunjukkan dua buah roket P dan Q mempunyai berat yang berbeza sedang
bergerak di ruang atmosfera bumi.
Rocket Q
Roket Q

Rocket P
Roket P

Earth
Bumi

Diagram / Rajah 9.1

(a) What is the meaning of weight?
Apakah yang dimaksudkan dengan berat?

[1 mark / 1 markah]

(b) Based on Diagram 9,
Berdasarkan Rajah 9,
(i) Contrast the height, gravity and gravitational potential energy between rocket P
and Q.

Bezakan ketinggian, graviti dan tenaga keupayaan graviti antara roket P dan Q.
(ii) Relate the height and gravity to make a deduction regarding the relationship

between height and gravitational potential energy.
Hubungkait ketinggian dan graviti untuk membuat satu kesimpulan berkaitan
dengan ketinggian dan tenaga keupayaan graviti.

[5 marks / 5 markah]

15

(c) Explain the bad effect of low gravity towards human body’s growth.
Terangkan keburukan kesan daripada graviti rendah terhadap tumbesaran badan
manusia.
[4 marks / 4 markah]

(d) Diagram 9.2 shows an Ariane-64 rocket.
Rajah 9.2 menunjukkan sebuah roket Ariane-64.

Diagram / Rajah 9.2
You are required to give suggestions on the rocket so that it can move faster and able to
escape from earth’s atmosphere.
Anda dikehendaki untuk memberi beberapa cadangan terhadap roket tersebut supaya ia
boleh bergerak dengan lebih cepat dan boleh melepasi ruang atmosfera bumi.
Using your knowledge of motion, forces and properties of materials, state and explain
the suggestions based on the following aspects:
Menggunakan pengetahuan anda tentang gerakan, daya dan sifat-sifat bahan, nyatakan
dan terangkan cadangan anda berdasarkan aspek-aspek berikut:
(i) Mass of rocket

Jisim roket
(ii) Type of fuel used

Jenis bahan api yang digunakan
(iii) Shape of rocket

Bentuk roket
(iv) Body of the rocket

Badan roket
(v) Size of exhaust

Saiz ekzos
[10 marks / 10 markah]

16