Analysis on the Public Examination Questions

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Analysis on the Public Examination Questions

The following tables list out the distribution of the past HKCEE and HKALE questions, as well as the past HKDSE questions:

Structured questions: HKCEE Paper 1, HKALE Paper 1 and HKDSE Paper 1B Multiple-choice questions: HKCEE Paper 2, HKALE Paper 2A and HKDSE Paper 1A

The numbers in the table refer to the question numbers. For example, HKDSE 12Q5 refers to question 5 in the 2012 HKDSE paper.

A. Heat and Gases

Topics Structured questions Multiple-choice questions a. Temperature, heat and internal energy

temperature and thermometers HKDSE: 15Q1(a) –

heat and internal energy – HKCEE: 09Q9, 09Q33

HKDSE: 12Q4, 17Q3 heat capacity and specific heat capacity HKCEE: 09Q4(a)(ii), 10Q4(a)

HKDSE: 12Q1(b),(c), 13Q1, 14Q1, 15Q1(b), 16Q1, 17Q1(b)

HKCEE: 09Q11, 10Q8, 10Q33 HKDSE: 12Q1, 15Q2, 15Q3, 17Q1

b. Transfer processes

conduction, convection and radiation HKCEE: 10Q3 HKDSE: 14Q1, 15Q1, 16Q1 c. Change of state

melting and freezing, boiling and

condensing HKCEE: 09Q3, 09Q4(a)(iii) HKCEE: 10Q9 latent heat HKCEE: 09Q4(a)(i), 10Q4(b)

HKDSE: 12Q1(a) HKCEE: 09Q10, 09Q12, 10Q11 HKDSE: 13Q2, 14Q2, 16Q2, 17Q2

evaporation – HKCEE: 10Q10

HKDSE: 12Q2, 13Q1 d. Gases

general gas law HKALE: 09Q7(a)

HKDSE: 12Q2(a), 13Q2, 14Q2(a), 15Q2, 16Q2

HKALE: 09Q35, 11Q42 HKDSE: 12Q3, 17Q4

kinetic theory HKALE: 09Q7(b), 11Q6(a),(b)(i),(ii) HKDSE: 12Q2(b), 14Q2(b),

15Q10(b)(iii), 17Q3

HKALE: 11Q41

HKDSE: 13Q3, 13Q4, 16Q3

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Instruction on Action Words

Most of the examination questions contain one or more key words (action words) which tell what candidates are required to do. These action words determine what response the candidates are expected to provide, and what kind of knowledge candidates should acquire. Candidates should familiarize themselves with these action words in order to give the appropriate response.

A. Knowledge expression

Some actions words indicate that candidates are required to give some facts directly, such as:

(a) describe – describe some physical process or procedures of experiments;

(b) state – give the core idea of physical laws or phenomena;

(c) define – give the basic definition of some physical quantities of physical terms.

Example 1:

State the Newton’s First Law of motion. (2 marks)

Every object remains in a state of rest or uniform motion 1A

unless acted upon by a net force. 1A

B. Comprehension

Some action words indicate candidates to show an understanding of knowledge acquired, such as:

(a) identify/distinguish – to find out the identity of unknown things;

(b) compare – to show the similarities and differences of some things;

(c) explain – to explain the facts given by stating relevant physical principles

Note that candidates should express their ideas in well-organized way. When quoting physical laws, candidates should not just quote the name without giving any detail.

Example 2:

Some alcohol is spilled on your left hand and an equal amount of water is spilled on your right hand. The alcohol disappears more quickly and your left hand feels colder than the right hand. Explain why. (3 marks) When a liquid evaporates, energy is absorbed from surroundings. 1A

The alcohol evaporates at a faster rate. 1A

Energy is taken from the left hand at a faster rate, therefore the left

hand feels colder. 1A

Give the core idea in a brief and clear way.

The details of principles must be stated.

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1 (2½ hours)

This paper must be answered in English GENERAL INSTRUCTIONS

(1) There are TWO sections, A and B, in this Paper. You are advised to finish Section A in about 50 minutes.

(2) Section A consists of multiple-choice questions in this question paper, while Section B contains conventional questions printed separately in Question-Answer Book B.

(3) Answers to Section A should be marked on the Multiple-choice Answer Sheet while answers to Section B should be written in the spaces provided in Question-Answer Book. The Answer Sheet for Section A and the Question-Answer Book for Section B will be collected separately at the end of the examination.

(4) The diagrams in this paper are NOT necessarily drawn to scale.

(5) The last two pages of the question paper contain a list of data, formulae and relationships which you may find useful.

INSTRUCTIONS FOR SECTION A (MULTIPLE-CHOICE QUESTIONS)

(1) Read carefully the instructions on the Answer Sheet. After the announcement of the start of the examination, you should first stick a barcode label and insert the information required in the spaces provided. No extra time will be given for sticking on the barcode label after the ‘Time is up’ announcement.

(2) When told to open this book, you should check that all the questions are there. Look for the words ‘END OF SECTION A’ after the last question.

(3) All questions carry equal marks.

(4) ANSWER ALL QUESTIONS. You are advised to use an HB pencil to mark all the answers on the Answer Sheet, so that wrong marks can be completely erased with a rubber. You must mark the answers clearly; otherwise you will lose marks if the answers cannot be captured.

(5) You should mark only ONE answer for each question. If you mark more than one answer, you will receive NO MARKS for that question.

(6) No marks will be deducted for wrong answers.

PAN LLOYDS PUBLISHERS LTD.

HONG KONG DIPLOMA OF SECONDARY EDUCATION EXAMINATION

MOCK EXAMINATION 1 PHYSICS PAPER 1

Not to be taken away before the end of the examination session

c679_set_M1_P1A.indd 1 17年6月22日上午11:34

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HKDSE Exam Series – Physics Mock Exam Papers (2018/19 Edition)

Section A: There are 33 questions. Questions marked with * involve knowledge of the extension component.

1. There is a puddle of hot water of mass 0.5 kg and initial temperature 70 °C. Air at 20 °C blows over the puddle at a rate of 0.2 kg s^–1 and becomes 25 °C after moving across the puddle. Find the time required to cool the puddle of hot water to 30 °C.

(given : specific heat capacity of water = 4200 J kg^–1 °C^–1 specific heat capacity of air = 200 J kg^–1 °C^–1)

A. 42 s

B. 210 s

C. 236 s

D. 420 s

2. The specific latent heat of vaporization of a substance is usually much greater than that of fusion. Which of the following statements gives the most suitable explanation?

A. The strength of intermolecular interactions in solids and liquids are similar while that in a gas is almost zero.

B. The boiling point of a substance is higher than the melting point.

C. The potential energy of molecules in gaseous state is the lowest.

D. The kinetic energy of molecules in gaseous state is the highest.

3. After the pressure of the air in a tyre of a car has been increased by pumping air into it, the number of moles of air in the tyre has increased by 10%. The Kelvin temperature of the air is increased by 1% and the internal volume of the tyre is increased by 1%. By what percentage has the pressure of the air in the tyre increased?

A. 8%

B. 10%

C. 11%

D. 12%

4. Two identical balls A and B are released from rest from different heights. When they almost reach the ground, the speed of ball A is double that of ball B. Neglect air resistance. Which of the following statements are correct?

(1) The accelerations of the two balls are the same.

(2) The distance travelled by ball A is double that of ball B.

(3) The time taken by ball A for the fall is double that by ball B.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

*

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Mock Exam 1

Go on to the next page 15. The figure below shows the positions of some particles in a medium before and while a sound wave

passes through.

Which of the following statements are correct?

(1) The separation between particles X and Z equals the wavelength of the wave.

(2) The displacement x of particle Y is the amplitude of the wave.

(3) Y is momentarily at rest.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 16.

The figure above shows a plane water wave travelling from region P to region Q across a boundary.

The wavefronts make an angle 30° with the boundary in region P and an angle 45° with the boundary in region Q. If the wave travels at 0.20 m s⁻¹ in region P, find the speed of the wave in region Q.

A. 0.14 m s⁻¹ B. 0.24 m s⁻¹ C. 0.28 m s⁻¹ D. 0.30 m s⁻¹

2017

Y

X x Z

X Y Z

direction of sound wave

equilibrium positioin of particles

positioin of particles as the wave passes through

region P

region Q 30° 45°

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19

B

This paper must be answered in English

1. After the announcement of the start of the examination, you should first write your Candidate Number in the space provided on Page 1 and stick barcode labels in the spaces provided on Pages 1, 3, 5, 7 and 9.

2. Refer to the general instructions on the cover of the Question Paper for Section A.

3. Answer questions.

4. Write your answers in the spaces provided in this Question-Answer Book. Do not write in the margins. Answers written in the margins will not be marked.

5. Graph paper and supplementary answer sheets will be provided on request. Write your Candidate Number, mark the question number box and stick a barcode label on each sheet, and fasten them with string this Question-Answer Book.

6. No extra time will be given to candidates for sticking on the barcode labels or filling in the question number boxes after the ‘Time is up’

announcement.

Please stick the barcode label here.

Candidate Number

PAN LLOYDS PUBLISHERS LTD

HONG KONG DIPLOMA OF SECONDARY EDUCATION EXAMINATION

PHYSICS PAPER 1

Section B: Question-Answer Book B

^{Use Only}^Marker’s Examiner’s Use Only Marker No. Examiner No.

Question No. Marks Marks 1

2 3 4 5 6 7 8 9 10 Total

c679_set_M1_P1B.indd 19 17年6月22日上午11:35

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Answers written in the margins will not be marked.

Answers written in the margins will not be marked. Answers written in the margins will not be marked.

20 HKDSE Exam Series – Physics Mock Exam Papers (2018/19 Edition)

Section B: Answer ALL questions. Parts marked with * involve knowledge of the extension component.

Write your answers in the spaces provided.

1. An energy conservation leaflet states that having a shower rather than a bath saves energy and water.

A student takes some measurements to test the statement.

(a) The student uses an electric heater to heat water for a shower. The results are recorded as follows.

Power rating of the water heater = 6 kW Time for shower to deliver 1 kg of water = 12 s Initial temperature of water = 21 °C

(i) Calculate the temperature of water from the shower.

(Given: specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹) (2 marks)

(ii) The shower lasts for 8 minutes. Calculate the total energy used by the electric heater to

heat the water. (1 mark)

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2. Figure 2 shows a bicycle inner tube in which the air pressure can be increased using a bicycle pump.

inner tube

volumbe 1.80 × 10^_4m³

volume 1.30 × 10^_3m³ valve

bicycle pump piston

Diagram NOT drawn to scale

The bicycle inner tube has a volume of 1.30 × 10^–3 m³ which remains constant even when air is pumped into it. The bicycle pump contains a maximum of 1.80 × 10^–4 m³ of air. When the piston is pushed in, all the air in the pump is transferred into the inner tube.

(a) Initially air in the inner tube has a pressure of 1.50 × 10⁵ Pa and a temperature of 27 °C.

(i) Calculate the number of moles of air in the inner tube initially. (2 marks)

(ii) Calculate the maximum number of moles of air transferred into the inner tube each time air is pumped into the tube by a bicycle pump when the air temperature is 27 °C.

(Given: atmospheric pressure = 1.00 × 10⁵ Pa) (1 mark)

*2014

Figure 2

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3. Ken of mass 50 kg jumps off a springboard into a swimming pool. Assume the air resistance and the size of Ken are negligible. (g = 9.81 m s^–2)

E / J

t / s 4000

3000

2000

1000

0

(a) Figure 3 shows how Ken’s potential energy changes with time, starting from the moment he leaves the springboard until he reaches the water surface.

(i) Find the height of the springboard above the water surface by taking his potential energy at

the water surface as zero. (2 marks)

(ii) Find the speed at which Ken jumps off the springboard. (2 marks)

(ii) Calculate the time taken by Ken to reach the water surface. (2 marks)

Figure 3

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1

Marker’s

Use Only Examiner’s Use Only Marker No. Examiner No.

Question No. Marks Marks Section A

Multiple- choice Section A Structured

question Section B Multiple-

choice Section B Structured

question Section C Multiple-

choice Section C Structured

question Section D Multiple-

choice Section D Structured

question

Please stick the barcode label here.

Candidate Number

PAN LLOYDS PUBLISHERS LTD

HONG KONG DIPLOMA OF SECONDARY EDUCATION EXAMINATION

MOCK EXAMINATION 1 PHYSICS PAPER 2 Question-Answer Book

Time allowed: 1 hour

This paper must be answered in English INSTRUCTIONS

1. After the announcement of the start of the examination, you should first write your Candidate Number in the space provided on Page 1 and stick barcode labels in the spaces provided on Pages 1, 3, 5 and 7.

2. This paper consists of FOUR sections, Sections A, B, C and D. Each section contains eight multiple- choice questions and one structured question which carries 10 marks. Attempt ALL questions in any TWO sections.

3. Write your answers in the spaces provided in this Question-Answer Book. Do not write in the margins. Answers written in the margins will not be marked. For multiple-choice questions, blacken the appropriate circle with an HB pencil. You should mark only ONE answer for each question. If you mark more than one answer, you will receive NO MARKS for that question.

4. Graph paper and supplementary answer sheets will be provided on request. Write your Candidate Number, mark the question number box and stick a barcode label on each sheet, and fasten them with string INSIDE this Question-Answer Book.

5. The diagrams in this section are NOT necessarily drawn to scale.

6. The last two pages of this Question-Answer Book contain a list of data, formulae and relationships which you may find useful.

7. No extra time will be given to candidates for sticking on the barcode labels or filling in the question number boxes after the ‘Time is up’

announcement.

c679_set_M1_P2.indd 1 17年6月22日上午11:46

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2

HKDSE Exam Series – Physics Mock Exam Papers (2018/19 Edition)

Section A : Astronomy and Space Science

Q.1: Multiple-choice questions

1.1 Which of the following statements about retrograde motion of planets as observed from Earth is INCORRECT?

A. Retrograde motion is the occasional westward drift of a planet against the background stars.

B. In the geocentric model of the universe, epicycles were introduced to explain retrograde motion.

C. Retrograde motion occurs when a planet occasionally rises in the west and sets in the east.

D. In the heliocentric model of the universe, retrograde motion occurs when Earth overtakes a planet as observed from the Sun.

1.2 What was the significance of Galileo’s discovery that Venus shows all phases from new to full?

A. It proved that Venus has an atmosphere.

B. It contradicts the geocentric model.

C. It allowed him to find the distance between Venus and the Sun.

D. It proved to other astronomers that his telescope was working properly.

1.3 According to Kepler’s laws of planetary motion, how will the orbit of a planet around the Sun be affected by the mass of the planet?

A. The mass of a planet has no effect on its period.

B. A more massive planet orbits the Sun at a higher average speed.

C. A more massive planet must have a larger orbital radius.

D. A more massive planet must have a longer period.

A B C D

○ ○ ○ ○

2015

A B C D

○ ○ ○ ○

A B C D

○ ○ ○ ○

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Q.2: Structured question

The Bohr’s model of the hydrogen atom is developed based on several postulates. It is an atomic model which successfully explains the behaviour of an electron in a hydrogen atom.

(a) One of the postulates of the Bohr’s model states that the centripetal force of an orbiting electron is provided by the electric force between the nucleus and the electron. The other states that angular momentum of an orbiting electron is integral multiples of h

2r.

(i) Based on the postulates stated, show that the orbital radius rn of the electron in a hydrogen atom is proportional to the square of the quantum number, n² , where n = 1, 2, 3, ... (3 marks)

(ii) Express the de Broglie wavelength of an orbiting electron in terms of the quantum number n, where n = 1, 2, 3, ... Hence, estimate the de Broglie wavelength of the electron occupying the

second excited state (n = 3) of a hydrogen atom. (2 marks)

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41 41 Mock Exam 3

Mock Exam 3

Paper 1

Section A

1. C

(2) is incorrect:

Heat is the energy transferred between two bodies due to their temperature difference, but not the energy stored in a body.

Misconceptions

It is a common misconception about heat. When the temperatures of two bodies are the same, the average kinetic energy of the molecules in the two bodies are the same, but not the heat.

2. C

B is correct:

When a liquid evaporates, molecules of higher kinetic energy escape from the liquid. The average kinetic energy of the remaining molecules decreases and therefore the temperature of the liquid drops.

C is incorrect:

Boiling occurs throughout the liquid, while evaporation only occurs at the surface of the liquid.

3. B

By crms = RT mN3

A, where mNA is the mass of 1 mole of gas,

c^rms of hydrogen gas =

×RT 2 103 ^–3

c^rms of oxygen gas =

×RT 3.2 103 ^–2

crms of hydrogen gas

crms of oxygen gas = ×

× 3.2 10

2 10

–2 –3

= 4

4. D

Take the downward direction as positive.

Let the height of the tower be h and the time taken by the object to fall from rest from the top to the mid-point of the tower be t.

By s = ut + 21 at², 0.5h = (0)t + 21 (9.81)t², h = 9.81t² ... (1)

Also,

h = (0)t + 21 (9.81)(t + 0.4)² h = 4.905(t + 0.4)² ... (2)

By (1) and (2),

9.81t² = 4.905(t + 0.4)² 2t² = t² + 0.8t + 0.16

t² - 0.8t - 0.16 = 0

t = 1

0.8 0.8 4 1 0.16 2

! 2

- - - -

-] ] ] ] ]

g gg g g s

t = 0.966 s or -0.166 s (rejected) Total time needed = (0.966 + 0.4) s

= 1.37 s

Guidelines

Use the equations of motion to express the time taken by the object to fall from the top to the mid-point of the tower, and also the total time taken by the object to reach the ground.

Alternative Solution:

By s = ut + 21 at² 0.5h = (0)t + 21 gt² t = gh ... (1) Also,

h = (0)t + 21 g(t + 0.4)² t + 0.4 = g

2 ... (2)h By (1) and (2),

t + 0.4 = 2 t t = 0.966 s

Total time needed = (0.966 + 0.4 s)

= 1.37 s

5. B

As the car moves along a straight line and the direction of motion remains unchanged throughout the journey, distance travelled = displacement

= area under the v-t graph

=

2

25-10 +30 #10

^ h

6 @

= 225 m

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47 Mock Exam 3

Section B

Marks 1. (a) Energy released by the interior in 1 s = Energy absorbed by the air in 1 s

= mcTT 1M

= 0.3 kg # 1000 J kg^-1 cC^-1 # (30 - 25) cC

= 1500 J 1A

Power = Energy released time = 1500 J

s

= 1500 W 1 1A 3

(b) The fin structure greatly increases the total surface area of the heat sink so that 1A the rate of heat transfer through conduction to the air can be greatly increased.

the rate of heat transfer through radiation to the surroundings can be greatly increased.

(c) The specific heat capacity of water is much higher than that of air, therefore more heat can be absorbed from the interior of the computer.

2. (a) The reaction time for a person is almost constant. 1A By s = vt, the graph of thinking distance against speed is a straight line with slope equal to the reaction

time. 1A 2

Guidelines

If the graph of s against v is a straight line, this means that s is proportional to v.

(b) When the car brakes, the kinetic energy of the car is changed into internal energy due to friction. 1A As the work done on the car is proportional to the braking distance and the kinetic energy is

proportional to the square of the speed of the car, the braking distance is proportional to the square of

the speed of the car. 1A

(no marks would be given if explain by the equations of motion) 2 (c) (i) Stopping distance = 16 m + 36 m

= 52 m 1A 1

(ii) The driver may delay applying the brake when noticing an accident. 1A

The reaction time increases, therefore the thinking distance increases. 1A 2

(d) From the graph, when v = 22 m s^-1, s = 36 m. 1A

W = ∆KE Fs =

21 mv² 1M

F # 36 m = 21 # 1000 kg # (22 m s^-1)²

F = 6720 N 1A 3

1A 2

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48

HKDSE Exam Series – Physics Mock Exam Papers (2018/19 Edition) Solution Guide

3. (a) First measure the length l of the cardboard. 1A When the vehicle passes through the light gate, the timer records the time duration t when the ray

in the light gate is blocked by the cardboard. 1A

The speed v of the vehicle can be determined by the relation l = vt. 1A 3 (b) (i) By conservation of momentum,

mu = (m + M)v 1M

u =

2 10

2 10 kg 0.5kg 0.10 kg m s

3

1

#

# + #

-

- -

^ h

= 25.1 m s^-1 1A 2

(ii) Some of the kinetic energy is converted into the internal energy of the plasticine/sound energy. 1A 1 (c) (i) In the vertical direction, take the downward direction as positive.

s = ut + 21 gt² 1M

0.4 m = (0)t + 21 (9.81 m s^-2)t²

t = 0.28557 s 1A

Horizontal distance = vt

= (25.1 m s^-1)(0.28557 s)

= 7.1678 m

≈ 7.17 m 1A 3

(ii) Range = sinv g

2 2

i 1M 7.1678 m = 9.81

25.1 sin 2 m s m s ²

2

1 i

-

^ -h

sin 2i = 0.11161

i = 3.20° or 86.8° 1A 2

Misconceptions

Some candidates may miss the solution i = 86.8°. Remember that for any angle i (where 0c < i < 90c), the angles of projection i and 90° - i give the same range.

4. (a) Ultrasound is a sound with frequency higher than the audible frequency range for humans. 1A The frequency range of ultrasound is above 20 000 Hz (20 kHz). 1A 2 (b) (i) Time for the ultrasonic wave to reach the bottom of the bar = 0.22ms

= 1 # 10^-4 s

Speed =

distance travelled 1Mtime

= 1 10

0.5m s

# ^-4

= 5000 m s^-1 1A 2

(ii) Time for the ultrasonic wave to reach the crack = 0.05 ms2

= 2.5 # 10^-5 s

Distance of crack from surface = speed # time 1M

= 5000 m s^-1 # 2.5 # 10^-5 s

= 12.5 cm 1A 2

(c) Used in sonar to detect landscapes of seabed / parking.

Imaging of foetus and internal organs 1A

Ultrasound cleaner

(Accept other reasonable answers) 1

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