Ce Phy Mock Paper A1

HKCEE Mock Examination

Subject Time Allowed Full Mark

: Physics (Paper 1) : 1 hour 45 minutes : 100

This paper must be answered in English.

Name: _____________________________

1.

Write your Name, Class and Class number in the spaces provided on this cover.

Class: Form 5 _____

2.

This paper consists of TWO sections, Section A and Section B. Section A carries 60 marks and Section B carries 40 marks.

Section A Question No.

Marks

1 3.

Answer ALL questions in each section. Write your answer in the spaces provided in this Question-answer Book. Supplementary answer sheet will be supplied on request. Write your Name, Class and Class Number on each sheet.

2 3 4 5

4.

5.

Some questions contain parts marked with an asterisk (*). In answering these parts, candidates are required to give paragraphlength answers. In each of these parts, one mark is allocated to assess candidates’ ability in effective communication. Unless otherwise specified, numerical answer should be exact or correct to three significant figures.

6 7 8 9 10 Section A Total

60

Section B Question No. 11 12 13 14 Section B Total

40

Page 1 of 20

Section A (60 marks) Answer ALL questions in this section and write your answers in the spaces provided. Question No.

1

2

3

4

5

6

7

8

9

10

Marks

3

8

8

7

6

6

6

6

5

5

Question 1 Queen Matilda is looking at King Stephen across the moat. The moat is full of water.

Figure 1a (a) The Queen sees the King’s crown reflected in the water. Draw, on the diagram, the path of a ray of light to show this happens. Draw an arrow, on your ray, to show the direction in which the light travels. (2 marks) The King throws his crown into the moat. It sinks to the bottom.

Figure 1b (b) Draw the path of the ray of light from the crown to his eyes. (1 mark)

[Total: 3]

Page 2 of 20

Question 2 The forces acting on the hands and feet of a rock climber change continually as the climber moves across the rock face. A climber of mass 70 kg who is carrying a rucksack of mass 20 kg is in the process of moving his right foot to new toehold. In the diagram he is temporarily at rest whilst looking for a suitable position for his foot.

Figure 2 (a) Show that the vertical components of the 200 N and 550 N forces add up to approximately 700 N. (2 marks)

(b) The climber is in equilibrium. (i) Explain briefly the term equilibrium. (2 marks)

(ii) Calculate the magnitude of force F acting on his left hand. (2 marks)

(c) The climber sees a suitable position and accelerates his free foot vertically upwards. Discuss the effect this might have on the force exerted on the other foot. (2 marks)

[Total: 8]

Page 3 of 20

Question 3 The diagram shows the inside of a fused 13A plug.

Figure 3 The following colours of wire are found in the plug. Blue brown green and yellow (a) Write down the names of the three wires in the plug and match the colours of wire as mentioned above. (3 marks) Blue: Brown: Green and yellow

(b) What colour wire should you connect to the fuse in the plug? (1 mark)

(c) The fuse helps to prevent fire caused by electrical faults. Explain briefly how it does this. (2 marks)

(d) State ONE advantage of using alternating current instead of direct current in mains supply. (2 marks)

[Total: 8]

Page 4 of 20

Question 4 The circuit shown in Figure 4 can be used as an electronic thermometer. (You may assume the battery has no internal resistance.)

Figure 4 The reading on the digital voltmeter can be converted to give the temperature of the thermistor T which is used as a temperature sensor. (a) Explain why the reading on the voltmeter increases as the temperature of the thermistor increases. (2 marks)

(b) When the thermistor is at 80.0 °C the voltmeter reading is 5.0V. Find the resistance of the thermistor at this temperature. (3 marks)

(c) When the thermistor is at 20.0 °C its resistance is 24.5Ω. Calculate the reading on the voltmeter. (2 marks)

[Total: 7]

Page 5 of 20

Question 5 Sound travels by means of longitudinal waves in air and solids. A progressive sound wave of wavelength λ and frequency f passes through a solid from left to right. In the diagram below line X represents the equilibrium positions of a line of atoms in the solid. Line Y represents the positions of the same atoms at a time t = t0.

Figure 5 Explain why the wave is longitudinal. (1 mark)

On line Y above label (i) two compressions (C), (ii) two rarefactions (R), (iii) the wavelength λ of the wave. (3 marks) The period of the wave is T. Along the line Z mark in the positions of the two compressions and the two rarefactions at a time t given by t = t0 + T/4. (2 marks) [Total: 6]

Page 6 of 20

Question 6 The graph in Figure 6 shows how the vertical component, v, of the velocity of a rocket varies with time, t, from its take-off on level ground to the highest point of its trajectory.

Figure 6 (a) Take readings from the graph to calculate the average vertical acceleration of the rocket from time t = 0 to time t = 0.60 s. (2 marks)

(b) Use the graph to estimate the maximum height reached by the rocket. (2 marks)

(c) Assume that air resistance is negligible. Calculate the time taken for the rocket to fall freely from its maximum height back to the ground. Take acceleration due to gravity, g, be 10ms-2. (2 marks)

[Total: 6]

Page 7 of 20

Question 7 Figure 7 shows an arrangement used to demonstrate the interference of sound waves. The two loudspeakers act as coherent sources of sound.

Figure 7 (a) Explain what is meant by the term coherent sources. (2 marks)

(b) In Figure 7, the loudspeakers are separated by 8.5m and are emitting sound of wavelength 0.77 m. When a sound engineer walks along the line AB, 65 m from the loudspeakers, he observes a regular rise and fall in the sound intensity. (i) Explain this observation. (2 marks)

(ii) A point P on the line AB is located such that the distances from the two speakers are 70.3 m and 68.76 m respectively, determine the interference condition at point P. (2 marks)

[Total: 6]

Page 8 of 20

Question 8 Figure 8 shows a beam of electrons about to enter the region between two charged metal plates.

Figure 8a (a) On Figure 8a continue the path of the electron beam between the plates for plates with a very small charge. (1 mark) Figure 8b shows another arrangement, similar to the first, but in this case the electron beam continues in a straight line because a magnet (which is not shown) has been placed near the plates.

Figure 8b (b) Explain where you would place the N-pole of the magnet in order to achieve this effect. You may draw on the diagram if you feel that it will make your answer clearer. (2 marks)

(c) Two long parallel wires R and S carry steady currents I1 and I2 respectively in the same direction. The diagram is a plan view of this arrangement. The directions of the currents are out of the page.

Figure 8c In the region enclosed by the dotted lines, draw the magnetic field pattern due to the current in wire R alone. Show at least three field lines. (2 marks) Mark on the diagram force on wire S due to the current in wire R. (1 mark) [Total: 6]

Page 9 of 20

Question 9 Graham makes a simple electric bell.

(a) Explain the use of the iron core. (1 mark)

(b) He closes the switch. (i) The hammer moves to the right and hits the gong. Explain why. (2 marks)

(ii) The hammer now moves back to the left. Explain why. (2 marks)

[Total: 5]

Page 10 of 20

Question 10

Read the following extracts and answer the following questions What is the problem for interstellar travel? Put simply it is the vast distances involved, indeed the distances are so great, it is almost impossible to visualise them. The nearest star to us is Proxima Centauri and this is 4.2 light years away. This means it takes light, which travels at 3 × 108 ms-1, 4.2 years to travel the distance. The distance from the Earth to the nearest star is a few thousand times greater than the distance to Pluto. The only craft that we have looked at that can even be considered are possibly a solar sail, one of the forms of enhanced nuclear fusion or the best situation of an antimatter beam core spacecraft. The reason we choose these craft is that they are the only ones capable of achieving a velocity that is an appreciable percentage of the speed of light, thereby reducing journey times to the order of a few decades instead of a thousand year! Unlike an aeroplane that has the air to push against a rocket must use the expelled rocket propellant. As the propellant is blasted out of the back of the rocket it pushes the spacecraft forward. We must find a completely new way to drive spacecraft forward that requires no propellant. Imagine using conventional chemical rockets for the journey and we want to carry a payload in the order of size of a bus. Even if we say that we will not need to slow down and allow 1000 years to make the journey the propellant required would still be greater than the entire mass in the universe! Clearly the amount of propellant required is an extremely important factor! On the other hand, solar sails depend on wind to be functional. In fact there is a wind in space. It is the solar wind. High speed particles and light photons are constantly being expelled by the Sun. It is the photons that are the driving force of a solar sail system as photons have momentum. Unlike the winds on Earth, the winds in space are constant high velocity. With no drag in space, the velocities that can be achieved are enormous.

(a) Calculate the distance represents by ONE light year. (1 mark)

(b) Explain why a rocket accelerates when propellant is expelled. (2 marks)

(c) ‘Photon’ is the particle form of light. Suggest a color for the sail of a solar sail spacecraft, explain your choice briefly. (2 marks)

[Total: 5]

Page 11 of 20

Section B (40 marks) Answer ALL questions in this section and write your answers in the spaces provided. Question No.

11

12

13

14

Marks

9

10

11

10

Question 11

P

Motion Sensor

Q

To Computer

Figure 11a

A trolley P of mass 0.5 kg moves with speed 10 m s-1 on smooth horizontal bench. It collides with a heavier trolley Q, which is initially at rest. After collision, P moves backwards in the opposite direction. Figure 11a shows the variation of the velocity of P with time as detected by the motion sensor.

Velocity (ms-1) 10

5

Time (s) 0 0.2

0.4

0.6

0.8

-5

Figure 11b (a) Find (i) the momentum of P before the collision, (ii) the change in momentum of P in the collision, (iii) the time of contact of P and Q, (iv) the average force acting on P during the collision. (5 marks) (b) Is the average force acting on Q during the collision equal to that acting on P? Explain briefly. (2 marks) (c) For safety reasons, the front and rear parts of cars should not be made of very strong material. Explain briefly. (2 marks) [Total : 9]

Page 12 of 20

Page 13 of 20

Question 12

Soft Iron Core

Figure 12a Figure 12a shows a transformer. (a) Explain why there is an e.m.f. across the secondary coil even though there is no electrical connection between the primary and secondary coils. (3 marks) (b) When the transformer is in use, the current in the secondary circuit is 3.2 A. Assume that the transformer may be considered 100% efficient. Calculate the current in the primary coil. (3 marks) The output from the power station generator is connected to a step-up transformer. The transformer is connected to transmission lines.

*(c) Explain why a step-up transformer is needed. Use your ideas about power losses in transmission. (4 marks) [Total: 10]

Page 14 of 20

Page 15 of 20

Question 13 (a) In an experiment to find the specific latent heat of fusion of ice, an electric heater, of power 200W, is used. The following readings are taken. mass of ice at 0 °C, before heating started, 0.54 kg mass of ice at 0 °C, after 300 s of heating, 0.36 kg (i) Calculate a value of the specific latent heat of fusion of ice. (2 marks) (ii) Explain, in molecular terms, how heat is transferred from the surface of a block of ice to its centre. (2 marks) (b) A room contains two electrically heated radiators. The radiators are exactly the same but contain different liquids.

The oil has a specific heat capacity of 2000 Jkg-1° C-1

The water has a specific heat capacity of 4200 Jkg-1° C-1

The radiators are switched on at the mains at 3 pm and left on for 4 hours. The graph shows how the temperature of the liquid in each radiator changes.

(i) Calculate the energy that needs to be transferred to raise the temperature of the water in the radiator by 20 °C. Given that the specific heat capacity of the water is 4200 Jkg-1°C-1. (2 marks) (ii) Most radiator available in the market are oil-filled. From the above information, suggest TWO reasons to support this. (2 marks) (iii) Suggest ONE feature of radiator to improve its effectiveness in heat transfer. Explain briefly. (2 marks) Page 16 of 20

(iv) The amount of energy needed to raise the temperature of the water-filled steel radiator is actually more than the correct answer to (b). Suggest a reason why it is so. (1 mark) [Total: 11]

Page 17 of 20

Question 14 Kate’s teacher wants to find how much beta radiation passes through different thicknesses of aluminium.

First he measures background radiation. It gives a reading of 60 counts per minute on the ratemeter. (a) Suggest two possible sources of background radiation. (2 marks) (b) Write down two safety precautions that he should take when using the beta source. (2 marks) He now records the count rate for different thicknesses of aluminium. The table shows the results.

(c) Finish the table. (2 marks) (d) (i) Plot the points on the grid opposite. (1 mark) (ii) Finish the graph by drawing the best curve. (1 mark) (e) Aluminium is rolled into sheets twenty millimetres thick in a rolling mill. A radioactive source and a detector are used to check the thickness of the sheet as it leaves the rollers.

(i) Why is beta radiation not suitable for checking twenty millimetre sheet? (1 mark) (ii) Suggest one type of radiation which could be used to check the thickness of twenty millimetre sheet. (1 mark) [Total: 10]

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END OF PAPER Page 19 of 20

Useful Formulae in Physics (a) Relationships between initial velocity u, uniform acceleration a, final velocity v and displacement travelled s after time t : v = u + at 1 s = ut + at 2 2 2 2 v = u + 2as (b) Potential energy gained by a body of mass m when raised through a height h is mgh. (c) Kinetic energy of a body of mass m moving with speed v is

1 mv 2 . 2

(d) Power = force × velocity (e) Equivalent resistance of two resistors R1 and R2 : (i)

in series = R1 + R2

(ii) in parallel = (f)

R1 R 2 R1 + R 2

Power = potential difference × current

Page 20 of 20