heat 2

Section ABahagian A

[60 marks][60 markah]

Answer all questions in this section.Jawab semua soalan dalam bahagian ini.

1. A student heats up a liquid of a certain mass to 83 °C as shown in Diagram A. Diagram B is a graph of heat energy supplied against mass of liquid used. The initial temperature of the liquid for each heating is the same. It is known that the specific heat capacity of the liquid is 300 J kg−1 °C−1.Seorang pelajar memanaskan satu cecair dengan jisim tertentu sehingga 83 °C seperti pada Rajah A. Rajah Bmenunjukkan graf bagi tenaga haba yang perlu dibekalkan melawan jisim cecair yang digunakan. Suhu awal cecair untuk setiap kali pemanasan adalah sama. Diketahui muatan haba tentu cecair itu adalah 300 J kg−1 °C−1.

Diagram A / Rajah A

Diagram B / Rajah B

(a) Explain why the graph did not start at the origin.Terangkan mengapa graf tidak melalui asalan.

[2 marks/markah]

(b) Calculate the initial temperature of the liquid.Hitungkan suhu awal cecair itu.

[2 marks/markah]

(c) If the liquid is replaced with another liquid that has a specific heat capacity of 1000 J kg−1 °C−1 and the mass of the liquid used is still the same, predict the gradient of the graph of energy against mass that is obtained.Sekiranya cecair itu digantikan dengan cecair yang muatan haba tentunya ialah 1 000 J kg−1 °C−1, dan jisim cecair yang digunakan masih sama, ramalkan kecerunan graf tenaga melawan jisim yang diperoleh.

[1 mark/markah]

2.

A student carried out an experiment to investigate the relationship between the pressure P and the temperature T of an ideal gas. A graph of P against T is plotted as shown in Diagram below.Seorang pelajar menjalankan eksperimen untuk menyiasat hubungan antara tekanan, P dan suhu T gas ideal. Sebuah graf P melawan T diplot seperti yang ditunjukkan dalam Rajah di bawah.

Diagram/Rajah

(a)

What is the SI unit of temperature?Apakah unit SI bagi suhu?

_____________________________________________________________________________________

[1 mark/markah]

(b)

Name the law involved in this experiment.Namakan hukum yang terlibat di dalam eksperimen ini.

_____________________________________________________________________________________

[1 mark/markah]

(c)

State two physical quantities which are constant in this experiment.Nyatakan dua kuantiti yang dimalarkan di dalam eksperimen ini.

_____________________________________________________________________________________

[2 marks/markah]

(d)

State the relationship between P and T.Nyatakan hubungan di antara P dan T.

_____________________________________________________________________________________

[1 mark/markah]

3.

Diagram below shows the apparatus set up in an experiment to study the relationship between the air pressure, P, and the temperature, T, of a fixed mass of air.Rajah di bawah menunjukkan susunan radas suatu eksperimen untuk menyiasat hubungan antara tekanan udara, P, dan suhu udara, T, bagi suatu jisim tertentu udara.

Diagram/Rajah

(a)

Write down the name of the instrument, X.Tuliskan nama bagi instrumen X.

_____________________________________________________________________________________

[1 mark/1 markah](b)

For the experiment described above, state what is theBagi eksperimen yang diperihalkan di atas, nyatakan apakah(i) manipulaed variable:

_________________________________________________________________pemboleh ubah dimanipulasikan

(ii) responding variable: __________________________________________________________________pemboleh ubah bergerak balas

[2 marks/2 markah](c)

Besides the mass of the air which is kept constant, state one other physical quantity of the air which is kept constant in this experiment.Di samping jisim udara yang ditetapkan, nyatakan satu lagi kuantiti fizik lain udara yang patut ditetapkan dalam eksperimen ini.

_____________________________________________________________________________________

[1 mark/1 markah](d)

Sketch a graph of the air pressure, P, against the absolute temperature, T, for this experiment.Lakarkan satu graf bagi tekanan udara, P melawan suhu mutlak T bagi eksperimen ini.

[2 marks/2 markah](e)

From the experiment, it was found that when the temperature of the air was 27 °C, the air pressure was 4.5 × 105 N m–2.What is the air pressure when the temperature is 67 °C?Dari eksperimen tersebut, didapati apabila suhu udara adalah 27°C, tekanan udara adalah 4.5 × 105 N m–2.Apakah tekanan udara apabila suhunya adalah 67°C?

[2 marks/2 markah]

4.

(a)

Two solids, X and Y, which have the same mass are placed in a hot bath and their temperaturesare plotted against time as shown in Diagram below.Dua pepejal X dan Y dengan jisim yang sama diletakkan dalam air mandi panas dan suhu dua pepejalitu diplotkan melawan masa seperti ditunjukkan dalam Rajah di bawah.

Diagram /Rajah

(i)Which of the solids, X or Y, has a higher melting point?Pepejal X dan Y manakah yang mempunyai takat lebur yang lebih tinggi?

__________________________________________________________________________________

[1 mark/1 markah]

(ii)

Heat is supplied to X and Y at the same rate. Which of the solids, X or Y, has a higherKadar haba yang dibekalkan kepada X dan Y adalah sama. Pepejal X dan Y manakah yangmempunyai

1.

specific heat capacity,muatan haba tentu yang lebih tinggi,

__________________________________________________________________________________

2.

specific latent heat of fusion? Explain your answer briefly.haba pendam tentu pelakuran yang lebih tinggi?Terangkan jawapan anda dengan ringkas.

__________________________________________________________________________________

[4 marks/4 markah]

(b)

A student carries out an experiment to find the specific latent heat of fusion of ice by themethod of mixture. He places 0.02 kg of ice at 0 °C into a plastic cup containing 0.05 kg ofwater at 20 °C.Seorang pelajar menjalankan satu eksperimen untuk mencari haba pendam tentu pelakuran ais dengancara campuran. Dia meletakkan 0.02 kg ais pada 0 °C ke dalam satu cawan plastik yang mengandungi

0.05 kg air pada 20 °C.

(i) Estimate the amount of heat required for the ice to change into water at 0 °C.(Specific latent heat of fusion of ice = 336 000 J kg−1)Anggarkan jumlah haba yang diperlukan oleh ais itu untuk berubah kepada air pada 0 °C.(Haba pendam tentu pelakuran ais = 336 000 J kg−1)

__________________________________________________________________________________

[2 marks/2 markah]

(ii)What is the amount of heat supplied by the water in the cup as it cools from 20 ��C to0 °C? (Specific heat capacity of water = 4 200 J kg−1K−1)Apakah jumlah haba yang dibekalkan oleh air dalam cawan itu apabila disejukkan daripada20 °C kepada 0 °C? (Muatan haba tentu air = 4 200 J kg−1K−1)

__________________________________________________________________________________

[2 marks/2 markah]

(iii)

What is the final temperature of the mixture? Explain briefly.Apakah suhu akhir bagi campuran itu? Terangkan secara ringkas.

__________________________________________________________________________________

[3 marks/3 markah]

5. Diagram A shows the arrangement of apparatus that contains a trapped air column and its length that is

immersed in the hot water. A thermometer is used to record the temperature, T. A graph of against T is

drawn as shown in Diagram B.Rajah A menunjukkan susunan radas yang mengandungi satu turus udara terperangkap

dengan panjang l yang direndam dalam air panas. Termometer digunakan untuk mencatatkan suhu T.

Satu graf melawan T dilukis seperti pada Rajah B.

Diagram A/Rajah A

Diagram B/Rajah B

(a) Why is the air column not heated directly?Mengapakah turus udara itu tidak dipanaskan secara terus?

[1 mark/markah]

(b)By using a suitable physics concept, explain why the graph of against T is a straight line.

Dengan menggunakan konsep fizik yang sesuai, terangkan mengapa graf melawan Tadalah

garis lurus.[1 mark/markah]

(c) Based on the graph in Diagram B, sketch a graph of pressure, P against temperature, T (in Kelvin) andanother graph of pressure, P against temperature (in °C) on the diagrams below.Berdasarkan graf pada Rajah B, lakarkan graf tekanan, P melawan suhu T (dalam Kelvin) dan graf tekanan, Pmelawan suhu, T (dalam °C) pada rajah di bawah.

[2 marks/markah]

(d) A driver who wants to drive from Johor Bahru to Penang plans to pump his car tyres.Seorang pemandu yang ingin memandu dari Johor Bahru ke Pulau Pinang mencadangkan untuk mengepam tayar keretanya.(i) If the standard pressure of the car tyre is a kPa, what pressure should he pump into the

car tyre? Tickthe answer in the correct empty box below.Jika tekanan piawai tayar keretanya ialah a kPa, antara yang berikut, yang manakah harus dilakukan olehnya untuk mengepam tayar keretanya? Tandakan jawapan yang betul pada petak kosong di bawah.

[1 mark/markah](ii) Explain your answer in (d)i.

Terangkan jawapan anda di (d)i.[1 mark/markah]

6.

(a)

Two solids, A and B, of the same mass are placed in a hot bath and their temperatures are plotted against time as shown in Diagram below.Dua pepejal A dan B dengan jisim yang sama diletakkan dalam air mandi yang panas dan suhu diplotkan melawan masa seperti ditunjukkan dalam Rajah di bawah.

Diagram / Rajah

(i)Which of the solids, A or B, has a higher melting point?

Pepejal A dan B yang manakah mempunyai takat lebur yang lebih tinggi?

_____________________________________________________________________________________

[1 mark/1 markah]

(ii)

Heat is supplied to A and B at the same rate. Which of the solids, A or B, has a higherKadar haba yang dibekalkan kepada A dan B adalah sama. Pepejal A dan B yang manakahmempunyai

_____________________________________________________________________________________

[1 mark/1 markah]

1.

specific heat capacity?muatan haba tentu yang lebih tinggi?

__________________________________________________________________________________

2.

specific latent heat of fusion?haba pendam tentu pelakuran yang lebih tinggi?

__________________________________________________________________________________

Explain your answers briefly.Terangkan jawapan anda dengan ringkas.

_____________________________________________________________________________________

[5 marks/5 markah]

(b)

A student carried out an experiment to find the specific latent heat of fusion of ice by the method of mixture. He placed 0.02 kg of ice at 0°C into a plastic cup containing 0.05 kg of water at 20°C.Seorang pelajar menjalankan satu eksperimen untuk mencari haba pendam tentu pelakuran ais dengan cara campuran. Dia meletakkan 0.02 kg ais pada suhu 0°C ke dalam sebuah cawan plastik yang mengandungi 0.05 kg air pada suhu 20 °C.(i) Estimate the amount of heat required for the ice to change into water at 0 °C.

(Specific latent heat of fusion of ice = 336 000 J kg−1)Anggarkan kuantiti haba yang diperlukan untuk ais berubah ke air pada 0 °C.(Haba pendam tentu pelakuran ais = 336 000 J kg−1)

[2 marks/2 markah]

(ii)What is the amount of heat supplied by the water in the cup as it is cooled from 20 °C to 0 °C?(Specific heat capacity of water = 4 200 J kg−1 K−1)Apakah kuantiti haba yang dibekalkan oleh air dalam cawan itu apabila menyejuk daripada 20 °C ke 0 °C?(Muatan haba tentu air = 4 200 J kg−1 K−1)

[2 marks/2 markah]

(iii)

What is the final temperature of the mixture? Explain briefly.Apakah suhu akhir bagi campuran itu? Terangkan secara ringkas.

_____________________________________________________________________________________

[2 marks/2 markah]

7.

The instrument shown in Diagram A is used to investigate the relationship between the pressureand the temperature of a fixed mass of gas. The graph of pressure P against temperature T obtainedis as shown in Diagram B.Instrumen yang ditunjukkan dalam Rajah A adalah untuk mengkaji hubungan antara tekanan dan suhubagi satu jisim tetap gas. Graf bagi tekanan P melawan suhu T diperoleh seperti ditunjukkan dalam Rajah B.

Diagram A / Rajah A

Diagram B / Rajah B

(a)

What is the relationship between P and TApakah hubungan antara P dengan T?

_____________________________________________________________________________________

[1mark /1 markah]

(b)

What is the value of T0 when pressure P is zero?Apakah nilai bagi T0 apabila tekanan P ialah sifar?

_____________________________________________________________________________________

[1mark /1 markah]

(c)

Use the kinetic theory to explainDengan menggunakan teori kinetik bagi gas, terangkan

(i) why the pressure of a gas inreases when the temperature increases,mengapa tekanan bagi suatu gas bertambah apabila suhu bertambah,

__________________________________________________________________________________

[1mark /1 markah]

(ii)

the condition of the molecules when the temperature is T0

keadaan molekul-molekul itu apabila suhu ialah T0.

__________________________________________________________________________________

[1mark /1 markah]

(d)

A gas is kept in a container with volume V and pressure 3.0 × 105 Pa at 0 °C.Satu gas disimpan dalam sebuah bekas dengan isi padu V dan tekanan 3.0 × 105 Pa pada suhu 0 °C.

(i) What is the pressure of the gas if the temperature is increased to 27 °C?

Apakah tekanan gas jika suhu ditambahkan sehingga 27 °C?

__________________________________________________________________________________

[1 mark/1 markah]

(ii)

What is the gas pressure if the gas at 0 °C is connected to an empty container withvolume 2 V and the entire gas is maintained at 0 °C?Apakah tekanan gas jika gas pada 0 °C disambungkan kepada satu bekas kosong dengan isi padu2 V dan seluruh gas itu dikekalkan pada 0 °C?

__________________________________________________________________________________

[1 mark/1 markah]

(e)

Explain why a gas which is compressed strong enough can be converted to a liquid.Terangkan mengapa satu gas yang dimampatkan cukup kuat boleh ditukarkan kepada cecair.

_____________________________________________________________________________________

[1 mark/1 markah]

8.

Diagram below shows 100 g of water at 0 °C and 100 g of ice being added respectively to beaker A and beaker B which contain 100 mℓ of water at 80 °C.Rajah di bawah menunjukkan 100 g air pada 0 °C dan 100 g ais masing-masing dicampurkan ke dalam bikar A dan B yang mengandungi 100 mℓ air pada suhu 80 °C.

DIAGRAM / RAJAH

(a)

Explain by using suitable concepts of physics, whether the adding of water or ice will cause the temperature of the water in the beaker to drop faster.Terangkan dengan menggunakan konsep fizik yang sesuai, sama ada pencampuran air ataupun ais akan menyebabkan suhu air dalam bikar menurun dengan lebih cepat.

_____________________________________________________________________________________

[2 marks/2 markah]

(b)

If the contents of beaker A are substituted with the same amount of ethanol (specific heat capacity = 2 450 J kg–1 °C–1), what are the changes that will take place?Sekiranya bahan yang dituangkan ke dalam bikar A diganti dengan kuantiti etanol yang sama (muatan haba tentu = 2 450 J kg–1 °C–1), apakah perubahan yang akan berlaku?

_____________________________________________________________________________________

[2 marks/2 markah]

(c)

What is the quantity of heat that should be supplied to the water in beaker B (before the addition of ice) so that the temperature of the water will rise from 25 °C to 80 °C?Berapakah kuantiti haba yang perlu dibekalkan kepada air di bikar B (sebelum pencampuran ais) supaya suhunya dinaikkan daripada 25 °C kepada 80 °C?

[Specific heat capacity of water = 4 200 J kg–1 °C–1][Muatan haba tentu air = 4 200 J kg–1 °C–1]

[2 marks/2 markah]

(d)

(i) 300 g of boiling water is poured into beaker B which contains 100 mℓ of water at 25 °C. Calculate the final temperature of the mixture.300 g air didih dituangkan ke dalam bikar B yang mempunyai 100 mℓ air pada suhu 25 °C. Kirakan suhu akhir campuran itu.

[2 marks/2 markah]

(ii)

What is the assumption made in calculating (d)(i)?Apakah andaian yang telah dibuat dalam pengiraan di (d)(i)?

__________________________________________________________________________________

[1 mark/1 markah]

Section BBahagian B


Answer any one question from this section.Jawab mana-mana satu soalan daripada bahagian ini.

9. (a) Diagram A shows the effect of evaporation on 500 cm3 of water placed in a container in a well-ventilated box for a duration of 2 hours.Rajah A menunjukkan kesan penyejatan bagi 500 cm3 air terkandung dalam suatu bekas yang diletakkandalam suatu kotak yang berpengaliran udara baik selama 2 jam.

Diagram B shows what happens to another 500 cm3 of water after 2 hours which is placed in the same box but installed with a turning fan.The initial temperature of the water in Diagram A is the same as that in Diagram B.Rajah B menunjukkan apa yang berlaku kepada 500 cm3 air yang lain selepas 2 jam, yang diletakkandalam kotak yang sama tetapi dipasang dengan satu kipas berputar.Suhu awal bagi air dalam Rajah A dan Rajah B adalah sama.

DIAGRAM A / RAJAH A

DIAGRAM B / RAJAH B

(i) What is meant by evaporation?Apakah yang dimaksudkan dengan penyejatan?

[1 mark/markah]

(ii) By using Diagram A and Diagram B, compare the amount of water left in the container and the condition of the air surrounding the water.

Relate the condition of the surrounding air with the loss of mass of water in the container.Hence make a deduction regarding the relationship between the condition of the surrounding air and the rate of evaporation of water.Dengan menggunakan Rajah A dan Rajah B, bandingkan kuantiti air yang tertinggal dalam bekasdan keadaan udara di sekeliling air itu.Hibungkaitkan keadaan udara sekeliling air kepada kehilangan jisim air dalam bekas itu. Dengandemikian, nyatakan suatu deduksi mengenai hubungan antara keadaan udara sekeliling air dan kadar air tersejat.

[5 marks/5 markah]

(b) Diagram C shows the simple structure of a refrigerator in which a cooling agent, freon, is made to flow through a system of copper pipes to produce cooling by evaporation. Explain briefly how the refrigerator works.State whether section A or section B is more suitable to be the freezing compartment.Rajah C menunjukkan struktur ringkas suatu peti sejuk di mana suatu agen penyejuk, freon, dipaksakan mengalir melalui suatu sistem paip kuprum untuk menghasilkan kesan penyejukan melalui proses penyejatan. Terangkan secara ringkas bagaimana suatu peti sejuk bekerja.Nyatakan sama ada bahagian A atau bahagian B lebih sesuai menjadi peti ais.

[4 marks/4 markah]

DIAGRAM C / RAJAH C

(c) A student intends to build a dish dryer by using electric power and a small fan to speed up the drying process for wet dishes.Based on the diagram shown above, you are required to give suggestions to design an efficient dish dryer able to dry 10 dishes and 10 cups at one time.Seorang pelajar ingin membina suatu alat pengering pinggan dengan menggunakan

kuasa elektrik dan suatu kipas kecil untuk mencepatkan proses pengeringan bagi pinggan basah.Berdasarkan Rajah D, anda dikehendaki memberi cadangan-cadangan mencipta reka suatu alat pengering pinggan yang cekap yang dapat mengeringkan 10 pinggan dan 10 cawan pada setiap kali.

DIAGRAM D / RAJAH D

By using the knowledge of factors to increase the rate of evaporation, electrical power and properties of material, explain the suggestions based on the following aspects:Dengan menggunakan pengetahuan tentang faktor-faktor yang boleh meningkatkan kadar penyejatan,kuasa elektrik dan sifat-sifat bahan, terangkan cadangan-cadangan anda berdasarkan aspek-aspek berikut:

(i) the choice of material used for the dish dryer cabinet,pemilihan bahan digunakan sebagai kabinet pengering pinggan,

(ii) the shape and size of the cabinet,bentuk dan saiz bagi kebinet,

(iii)

the position of the 200 W heater,kedudukan bagi pemanas berkuasa 200 W,

(iv)the position of a small exhaust fan and a small lamp for illumination,kedudukan bagi suatu kipas ekzoz kecil dan suatu lampu kecil untuk pencahayaan,

(v) the design of the electrical circuit for the heater, fan and lamp in parallel.reka bentuk litar elektrik bagi pemanas, kipas dan lampu secara selari.

[10 marks/10 markah]

10. (a) Diagram A shows the effect of evaporation on 500 cm3 of water placed in a container in a well-ventilated box for a duration of 2 hours.Rajah A menunjukkan kesan penyejatan bagi 500 cm3 air terkandung dalam suatu bekas yang diletakkan dalam suatu kotak yang berpengaliran udara baik selama 2 jam.

Diagram B shows what happens to another 500 cm3 of water after 2 hours which is placed in the same box but installed with a turning fan.The initial temperature of the water in Diagram A is the same as that in Diagram B.Rajah B menunjukkan apa yang berlaku kepada 500 cm3 air yang lain selepas 2 jam, yang diletakkan dalam kotak yang sama tetapi dipasang dengan satu kipas berputar.Suhu awal bagi air dalam Rajah A dan Rajah B adalah sama.

Diagram A/Rajah A

Diagram B/Rajah B

(i) What is meant by evaporation?Apakah yang dimaksudkan dengan penyejatan?

[1 mark/1 markah]

(ii) Using Diagram A and Diagram B, compare the amount of water left in the container and the condition of air surrounding the water.Relate the condition of the surrounding air with the loss of mass of water in the container.Hence make a deduction regarding the relationship between the condition of the surrounding air and the rate of evaporation of water.Dengan menggunakan Rajah A dan Rajah B, bandingkan kuantiti air yang tertinggal dalam bekas dan keadaan udara di sekeliling air itu.Hubungkaitkan keadaan udara sekeliling air kepada kehilangan jisim air dalam bekas itu. Dengan demikian, nyatakan suatu deduksi mengenai hubungan antara keadaan udara sekeliling air dan kadar air tersejat.

[5 marks/5 markah]

(b) Diagram C shows the simple structure of a refrigerator in which a cooling agent, freon, is made to flow through a system of copper pipe to produce cooling by evaporation.Explain briefly how the refrigerator works.State whether section A or section B is more suitable to be the freezing compartment.

Rajah C menunjukkan struktur ringkas suatu peti sejuk di mana suatu agen penyejuk, freon, dipaksakan mengalir melalui suatu sistem paip kuprum untuk menghasilkan kesan penyejukan melalui proses penyejatan.Terangkan secara ringkas bagaimana suatu peti sejuk bekerja.Nyatakan sama ada bahagian A atau bahagian B lebih sesuai menjadi peti ais.

[4 marks/4 markah]

Diagram C RefrigeratorRajah C Peti sejuk

(c) A student intends to build a dish dryer using electric power and a small fan to speed up the drying process for wet dishes.Based on the diagram above, you are required to give suggestions to design an efficient dish dryer able to dry 10 dishes and 10 cups at one time.Seorang pelajar ingin membina suatu alat pengering pinggan dengan menggunakan kuasa elektrik dan suatu kipas kecil untuk mencepatkan proses pengeringan bagi pinggan basah.Berdasarkan Rajah D, anda dikehendaki memberi cadangan-cadangan mencipta reka suatu alat pengering pinggan yang cekap yang dapat mengeringkan 10 pinggan dan 10 cawan pada setiap kali.

Diagram D/Rajah D

Using the knowledge of factors to increase the rate of evaporation, electrical power and properties of material, explain the suggestions based on the following aspects:Dengan menggunakan pengetahuan tentang faktor-faktor yang boleh meningkatkan kadar penyejatan, kuasa elektrik dan sifat-sifat bahan, terangkan cadangan-cadangan anda berdasarkan aspek-aspek berikut:(i) the choice of material used for the dish dryer cabinet,

pemilihan bahan digunakan sebagai kabinet pengering pinggan,(ii) the shape and size of the cabinet,

bentuk dan saiz bagi kebinet,(iii)

the position of the 200 W heater,kedudukan bagi pemanas berkuasa 200 W,

(iv)the position of a small exhaust fan and a small lamp for illumination,kedudukan bagi suatu kipas ekzoz kecil dan suatu lampu kecil untuk pencahayaan,

(v) the design of the electrical circuit for the heater, fan and lamp in parallel.reka bentuk litar elektrik bagi pemanas, kipas dan lampu secara selari.

[10 marks/10 markah]

Section CBahagian C


Answer any one question from this section.Jawab mana-mana satu soalan daripada bahagian ini.

11.

(a)

You are asked to study the characteristics of the liquids shown in Table below and determine the suitability of each of them to be used as a cooling agent, replacing freon, in an air-conditioner.Anda sebagai seorang penyelidik telah ditugaskan untuk mengkaji ciri-ciri cecair dalam Jadual di bawah untuk digunakan sebagai cecair penyejuk yang boleh menggantikan cecair freon bagi penyaman udara.

Table /Jadual

i. What is meant by the specific latent heat of vaporisation of a liquid?Apakah yang dimaksudkan dengan haba pendam tentu pengewapan bagi suatu cecair?

[1 mark/markah]ii. Explain the suitability of each of the liquids in Table below to be used as a cooling

agent in an air conditioner. Hence determine which liquid is the most suitable to be used. Give reasons for your choice.Terangkan kesesuaian setiap ciri cecair dalam Jadual di atas untuk dijadikan cecair penyejuk bagi penyaman udara dan seterusnya tentukan cecair yang paling sesuai untuk dijadikan cecair penyejuk bagi penyaman udara. Berikan sebab bagi pilihan anda.

[10 marks/markah](b)

A marathon runner can generate as much as 800 J of heat per second. Half of the heat generated is lost from the body through evaporation of sweat.Seorang pelari dalam suatu maraton boleh menjanakan sehingga 800 J tenaga haba setiap saat. Separuh daripada tenaga haba ini dihilangkan daripada badan pelari melalui penyejatan air peluhnya.i. Based on the kinetic theory of matter, explain why evaporation of sweat from the body

of the runner can cause heat to be lost from the body.Berdasarkan teori kinetik jirim, terangkan mengapa kehilangan air oleh penyejatan dapat menyejukkan badan pelari itu.

[3 marks/markah]ii. State two factors which can increase the rate of evaporation of a liquid.

Nyatakan dua faktor yang dapat meningkatkan kadar penyejatan air.[2 marks/markah]

(c)

Calculate the mass of sweat evaporated from the body of the marathon runner if he finishes the race in 2 hours.[Take the specific latent heat of evaporation of sweat as 2.26 × 106 J kg–1]Hitungkan jisim air yang tersejat daripada badan seorang pelari yang telah menamatkan suatu perlumbaan yang mengambil masa 2 jam.[Abaikan pengaruh haba persekitaran. Haba pendam tentu pengewapan air ialah 2.26 × 106 J kg–1]

[4 marks/markah]

12.

Diagram below shows the heating methods J, K, L, M and N for the same quantity of water but in the different heating conditions.Rajah di bawah menunjukkan cara mendidih J, K, L, M dan N bagi kuantiti air yang sama tetapi dalam keadaan pemanasan yang berlainan.

Diagram / Rajah

(a)

(i) What is meant by boiling?Apakah yang dimaksudkan dengan pendidihan?

[1 mark/markah](ii)Boiling is used in the fractional distillation of petroleum. Explain how fractional

distillation iscarried out.Salah satu kegunaan pendidihan ialah penyulingan berperingkat petroleum. Terangkan bagaimana penyulingan berperingkat petroleum dijalankan.

[4 marks/markah](iii)

You are assigned to determine the effective boiling method. Investigate methods J, K, L, M and N inDiagram above and relate the following aspects:Anda ditugaskan untuk menentukan cara mendidih yang berkesan. Kaji cara J, K, L, M dan N dalam Rajah di atas dan pertimbangkan aspek berikut:

• Impurities dissolved in the waterBendasing dilarutkan dalam cecair

• Surface area of the waterLuas permukaan cecair

• Air pressureTekanan udara

• Rate of heatingKadar permanasan

Explain the suitability of the aspects and then determine the most suitable method of boiling waterefficiently. Give reasons for your answer.Terangkan kesesuaian aspek-aspek itu dan seterusnya tentukan cara yang paling sesuai untuk mendidihkan air dengan berkesan. Berikan sebab bagi pilihan anda.

[10 marks/markah]

(b)

(i) A container has a volume of 250 cm3 and the gas pressure in it is 1 × 105 Pa. Then the container iscompressed into 1/3 of its original volume. How much is the gas pressure now?Sebuah bekas mempunyai isi padu 250 cm3 dan tekanan gas di dalamnya ialah 1 × 105 Pa. Kemudian bekas itu dimampatkan menjadi 1/3 daripada isi padu asalnya. Berapakah tekanan gas sekarang?

[2 marks/markah](ii) After a process, a container that has a volume of 40 cm3, has a gas pressure of 3 atm and

temperatureof 37°C. If the atmospheric pressure and temperature of the air in the container before the process is2.7 atm and 27°C respectively, calculate the original volume of the container.Selepas satu proses, sebuah bekas yang berisi padu 40 cm3, mempunyai tekanan udara 3 atm dan suhu37°C. Jika tekanan atmosfera dan suhu udara dalam bekas itu sebelum proses itu masing-masing ialah 2.7atm dan 27°C, kirakan isi padu asal bekas itu.

[3 marks/markah]

SMK TAMAN TUN DR. ISMAIL Jawapan

SPM Fizik Tingkatan 4,5 - Untitled Kertas 21.

(a) During heating, some energy is lost to the surrounding causing more energy to be used.

(b) Q = mcθ Since a graph of Q against m is plotted, the gradient of the graph is cθ

The gradient of the graph, cθ =

300 θ = 18 000 θ = 60 °C So the initial temperature of liquid is (83 – 60) °C = 23 °C

(c) The gradient of the graph increases.

2. (a) K

(b) Pressure lawHukum tekanan

(c) The mass of gas and the volume of gasJisim gas dan isipadu gas

(d) P is directly proportional to T.P berkadar langsung dengan T.

3. (a) Bourdon gauge/Tolok Bourdon

(b) (i) Temperature/Suhu (ii) Air pressure/Tekanan udara

(c) Volume/Isi padu

(d)

(e)

4.

(a) (i) Solid Y (ii) 1. X has a higher specific heat capacity. X can absorb more heat with little increase in temperature. 2. X has a higher specific latent heat of fusion. It absorbs more heat in order to melt and its temperature remains constant for a longer time when it is melting.

(b) (i) Q = ml = 0.02(336 000) = 6 720 J (ii) Q = mcθ = 0.05(4 200)(20-0) = 4 200 J (iii) 0 °C – This is because the heat required to change from the solid to the liquid state is more than heat supplied by the water when cooled from 20°C to 0°C. – The heat supplied by the water at 20°C is not sufficient to melt all the 0.02 kg of ice

5.

(a) Direct heating will cause the increment in the air column too fast. This will cause the mercury column to spurt out.

(b) According to pressure law, pressure is directly proportional to temperature. Pressure is defined as the

length of air column, l, operationally. So is a constant.

(c)

(d) i. a – 20 kPa ii. When travelling long distances, friction between the tyres with air and the road will occur. Heat is produced and this increases the temperature. According to the gas law, when temperature increases, pressure also increases. Excess pressure is very dangerous. So for

long distance travelling, the car tyre pressure should be lowered.

6.

(a) (i) B has a higher melting point. (ii) 1. A has a higher specific heat capacity. A and B are heated at the same rate means that the same amount of energy is given to them for the same period of time. From the graph, the temperature of B is higher than the temperature of A for the same period of time. According to energy = mc(ΔT), a greater rise in temperature for the same amount of energy means the specific heat capacity is smaller. 2. A has a higher latent heat of fusion. From the graph, the melting time for A is longer than that for B. Hence, more energy is given to A than to B in melting. Because energy = (Δm)(l), if more energy is supplied to the same mass of solid it means that the specific latent heat is higher.

(b) (i) Energy = (Δm)(l) = (0.02)(336 000) = 6 720 J (ii) Energy = mc(ΔT) = (0.05)(4 200)(20 – 0) = 4 200 J (iii) The energy given by the water is smaller than the energy needed to melt all the ice. Not all the ice can be melted. The product is a mixture of ice and water in equilibrium. The mixture is at 0°C.

7.

(a) P is directly proportional to T.

(b) -273°C or 0 Kelvin

(c) (i) When the temperature increases, the kinetic energy and average speed of gas molecules increase. Hence, the rate and magnitude of collision between the gas molecules and the wall of the container increase, therefore the pressure increases. (ii) At T0, the gas molecules lose all the kinetic energy, hence the gas molecules are stationary, whereas the pressure volume of the gas are zero.

(d) (i) P1T2 = P2T1, pressure P2

=

= 3.3 × 105 Pa

(ii) P2T2 = P3 T3, pressure P3

=

= 1.0 × 105 Pa

(e) High pressure, very small volume where the average distance between the gas molecules = the distance between liquid molecules. In this great collision, the gas molecules which have lost a lot of energy will become the molecules of a liquid.

8.

(a) Mixing with 100 g of water will cause the temperature of the water in the beaker to drop faster. This is because the specific heat capacity of water is larger than that of ice.

(b) The temperature of the water in the beaker will drop at a slower rate compared to mixing 100 g of the water before this. This is because the specific heat capacity of ethanol is lower than that of water.

(c) Q = mcθ Quantity of heat, Q = 0.1 × 4 200 × (80 – 25) = 23 100 J

(d) (i) Heat supplied by 300 g of boiling water = heat received by 100 mℓof water. 0.3 × 4 200 × (100 – θ) = 0.1 × 4 200 × (θ – 25) 30 – 0.3θ = 0.1θ –2.5 θ= 81.25 °C (ii) All the heat supplied is transferred directly to the water in beaker B. There is no heat loss to the surroundings.

9.

(a) (i) Evaporation is the process of spontaneous change of a substance from liquid state into gaseous state. Penyejatan adalah proses perubahan spontan bahan daripada keadaan cecair ke keadaan gas. (ii) In Diagram A, the surrounding air is not moving, more water is left after 2 hours. In Diagram B, the surrounding air is moving, less water is left after 2 hours. Dalam Rajah A, udara sekeliling tidak bergerak, lebih banyak air ditinggalkan selepas 2 jam. Dalam Rajah B, udara sekeliling bergerak, kurang air ditinggalkan selepas 2 jam. In still air, the loss of mass of water from the container is less. In moving air, the loss of mass of water from the container is greater. Hence, moving air increases the rate of evaporation of water. Dalam udara pegun, kehilangan jisim air dari bekas adalah berkurang. Dalam udara bergerak, kehilangan jisim air dari bekas adalah lebih banyak. Maka, udara bergerak

meningkatkan kadar penyejatan air.

(b) The electric pump compresses the freon vapour into liquid and forces it up along the copper pipe. When flowing through the valve, freon liquid vapourises into gaseous freon. Heat is absorbed from the surrounding air during this vaporization process. The surrounding air cools. Section A is more suitable to be the freezing compartment, as it is directly cooled by the coolant, freon. Pam elektrik memampatkan wap Freon kepada cecair dan memaksanya bergerak ke atas di sepanjang paip kuprum. Apabila bergerak melalui injap, cecair Freon mengewap menjadi wap Freon. Haba diserap daripada udara sekeliling semasa proses pengewapan. Udara sekeliling menyejuk. Bahagian A sesuai dijadikan peti ais, sebab ia disejukkan terus oleh penyejuk, Freon.

(c) 1. The material for the cabinet must be galvanized zinc or stainless steel. Bahan untuk kabinet harus digalvani dengan zink atau keluli tahan karat. 2. So that it can withstand high heat, does not rust easily. Supaya ia tahan haba tinggi, tidak mudah karat. 3. Rectangular shape, size 60 cm × 40 cm × 50 cm so that it is large enough to accomodate the 10 dishes and 10 cup. Bentuk segi empat, saiz 60 cm × 40 cm × 50 cm supaya alat itu cukup besar untuk memuatkan 10 pinggan dan 10 cawan. 4. The 200 W heater should be placed at the bottom of the cabinet. Pemanas 200 W harus diletakkan di bawah kabinet. 5. As hot air created by the heater will rise up to dry the dishes on top. Apabila udara panas dihasilkan oleh pemanas, ia akan bergerak ke atas untuk mengeringkan pinggan di bahagian atas. 6. The small exhaust fan should be at the top and back of the cabinet. Kipas ekzos harus diletakkan di atas dan di belakang kabinet. 7. To extract the air out of the cabinet, as moving air increases the rate of evaporation of water from the dishes. Untuk mengeluarkan udara dari kabinet, sebab udara bergerak menambahkan kadar penyejatan air dari pinggan. 8. The small lamp must shine to the back of the cabinet, to provide good illumination of the contents of the cabinet. Lampu kecil harus memancar ke belakang kabinet untuk membekalkan pencahayaan

yang baik bagi kandungan kabinet. 9. Circuit design: Reka bentuk litar:

10.

(a) (i) Evaporation is the process of spontaneous change of a substance from liquid state into gaseous state.Penyejatan adalah proses perubahan spontan bahan daripada keadaan cecair ke keadaan gas.

(ii) In Diagram A, surrounding air is not moving, more water is left after 2 hours. In Diagram B, surrounding air is moving, less water is left after 2 hours.Dalam Rajah A, udara sekeliling tidak bergerak, lebih banyak air ditinggalkan selepas 2 jam. Dalam Rajah B, udara sekeliling bergerak, kurang air ditinggalkan selepas 2 jam.In still air, loss of mass of water from the container is less. In moving air, loss of mass of water from the container is greater. Hence, moving air increases the rate of evaporation of water.Dalam udara pegun, kehilangan jisim air dari bekas adalah berkurang. Dalam udara bergerak, kehilangan jisim air dari bekas adalah lebih banyak. Maka, udara bergerak meningkatkan kadar penyejatan air.

(b) The electric pump compresses the freon vapour into liquid and force it up along the copper pipe. When flowing through the valve, freon liquid vapourises into gaseous freon. Heat is absorbed from the surrounding air during this vaporization process. The surrounding air cools. Section A is more suitable to be the freezing compartment, as it is directly cooled by the coolant freon.Pam elektrik memampatkan wap Freon kepada cecair dan memaksanya bergerak ke atas di sepanjang paip kuprum. Apabila bergerak melalui injap, cecair Freon mengewap menjadi wap Freon. Haba diserap daripada udara sekeliling semasa proses pengewapan. Udara sekeliling menyejuk. Bahagian A sesuai dijadikan peti ais, sebab ia disejukkan terus oleh penyejuk, Freon.

(c) 1. Material for the cabinet must be galvanized zinc or stainless steel. Bahan untuk kabinet harus digalvani dengan zink atau keluli tahan karat.2. So that it can stand high heat, does not rust easily. Supaya ia tahan haba tinggi, tidak mudah karat.3. Rectangular shape, size 60 cm × 40 cm × 50 cm. Bentuk segi empat, saiz 60 cm × 40 cm × 50 cm.4. The 200 W heater should be placed at the bottom of the cabinet. Pemanas 200 W harus diletakkan di bawah kabinet.5. As hot air created by the heater will rise up to dry the dishes on top.

Apabila udara panas dihasilkan oleh pemanas, ia akan bergerak ke atas untuk mengeringkan pinggan di bahagian atas.6. The small exhaust fan should be at the top and back of the cabinet. Kipas ekzos harus diletakkan di atas dan di belakang kabinet.7. To extract the air out of the cabinet, as moving air increases the rate of evaporation of water from the dishes. Untuk mengeluarkan udara dari kabinet, sebab udara bergerak menambahkan kadar penyejatan air dari pinggan.8. The small lamp must shine to the back of the cabinet, to provide good illumination of the contents of the cabinet. Lampu kecil harus memancar ke belakang kabinet untuk membekalkan pencahayaan yang baik bagi kandungan kabinet.9. Circuit design: Reka bentuk litar:

11.

(a) i. The specific lantent heat of vaporisation of a liquid is the amount of heat required to change 1 kg of the liquid to gaseous state at constant temperature.Haba tentu pengewapan bagi suatu cecair ialah kuantiti haba yang diperlukan untuk menukarkan 1 kg cecair itu kepada keadaan gas tanpa perubahan suhu. [1 m]ii. – the density must be lowcecair ini harus berketumpatan rendah [1 m]– so that the airconditionaer unit is not too heavy/the cooling agent can flow easilysupaya penyaman udara tidak terlalu berat/agen penyejuk boleh mengalir dengan mudah [1 m]– boiling point must be lowtakat didih mesti rendah [1 m]– so that the cooling agent is volatile/ evaporates easily at low temperature;supaya agen penyejuk menyejat dengan mudah pada suhu rendah [1 m]– specific heat capacity must be low,cecair ini harus mempunyai muatan haba tentu yang rendah. [1 m]– so that it can be heated quickly/becomes liquid when compressedsupaya cepat dipanaskan menjadi cecair apabila dimampatkan. [1 m]– the specific latent heat of vaporisation must be highcecair ini mempunyai haba pendam tentu pengewapan yang tinggi [1 m]– so that it absorbs more heat from the surrounding air when it evaporises through the valve in the copper tube/more efficientsupaya menyerap banyak haba daripada udara sekeliling apabila ia menyejat melalui injap dalam tiub kuprum kepada wap dan dibebaskan di ruang bilik.– Liquid M is most suitable.Cecair M adalah paling sesuai. [1 m]– Liquid M has a low density, low boiling point, low specific heat capacity and moderate specific latent heat of vaporisation.Cecair M mempunyai haba pendam tentu pengewapan yang paling rendah, muatan haba

tentu yang rendah, takat didih yang paling rendah dan ketumputan yang sederhana [1 m]

(b) i. – Sweat molecules absorb heat from the body and escape as gas molecules Molekul-molekul air peluh terlepas sebagai wap selepas menyerap tenaga haba daripada badan pelari untuk mengatasi daya lekitan antara molekulmolekul air [1 m]– energy is needed to break the bonds between the liquid molecules molekul-molekul air peluh yang masih tertinggal mempunyai tenaga kinetik purata yang lebih rendah. [1 m]– Sweat molecules which are left on the body have less kinetic energy and the temperature decreases. Jadi, air peluh kehilangan tenaga haba semasa penyejatan dan menyebabkan suhu badan menurun. [1 m]ii. 1. Increase the surface area of the liquid Tambahkan luas permukaan cecair [1 m]2. Increase the movement of air molecules outside the liquid surface [1 m] Tambahkan pergerakan molekul air di luar permukaan cecair

(c) Rate of heat produced by the runnerKadar haba dijanakan oleh pelari itu= 1 (800) = 400 J s–1. [1 m] 2Total heat produced in 2 hours,Jumlah haba dihasilkan dalam 2 jam,Q = 400 × 2 × 60 × 60 [1 m]Total heat produced = Latent heat of vaporisation of sweat.Jumlah haba yang dihasilkan = Haba pendam tentu pengewapan peluh [1 m]400 × 2 × 60 × 60 = m L [1 m]Mass of sweat evaporated,Jisim peluh yang menyejat,m = (400 × 2× 60× 60) 2.26 × 106

= 1.27 kg [1 m]

12.

(a) i. – Boiling is the conversion of a liquid to a vapour in the form of gas bubbles. The whole of liquid becomes vapour at the boiling point. [1 m] ii. – Petroleum consists of a number of hydrocarbons that have different boiling points. [1 m] – Raw oil that is hot (in the form of vapour) is passed through a fractional distillation tube which has an opening at the bottom. [1 m] – Vapour will rise up. Hydrocarbons that have low boiling points will start to condense at the upper part of the tube. Examples are petrol, kerosene and diesel. [1 m] – Hydrocarbons that have higher boiling points will condense at a lower part of the tube. [1 m] iii. – Impurities are dissolved in a smaller volume of liquid or no impurities are added.

[1 m] – This is because impurities will make it more difficult for the water molecules to turn into gas molecules. This will raise the boiling point and lengthen the time taken for boiling. [1 m] – Lower air pressure. [1 m] – This is because it is easier for the vapour molecules to escape from the liquid into the air when the air pressure is low. [1 m] – The higher the place is, the lower the air pressure will be. [1 m] – The surface area of a liquid does not affect the boiling point of the liquid. [1 m] – The rate of heating is faster. [1 m] – More energy is supplied to the water molecules so that more water molecules can escape from the water to the air. [1 m] – Method M is chosen. [1 m] – This is because there are no impurities dissolved in the liquid, the air pressure is low as it is located at a high area and has a high rate of heating. [1 m]

(b) i. – P1V1 = P2V2

(1 × 105)V 1 = P2 P2 = 3 × 105 Pa [1 m]

ii. –

[1 m] – The original volume of the container is 43.011 cm3. [1 m]

heat 2

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