B

Name
OXFORD UNIVERSITY PRESS
Class
NEW SENIOR SECONDARY
Class number
PHYSICS AT WORK
(SECOND EDITION)

Teacher's
MOCK EXAMINATION (Set 1) Use Only

PHYSICS PAPER 1 Question No. Marks

Section B: Question-Answer Book B 1 /6

This paper must be answered in English 2 /6

3 /7
INSTRUCTIONS FOR SECTION B
(1) After the announcement of the start of the examination, 4 /8
you should first insert your information in the spaces 5 /9
provided on Page 1.
6 /8
(2) Refer to the general instructions on the cover of the
Question Paper for Section A. 7 / 10
(3) Answer ALL questions.
8 / 11
(4) Write your answers in the spaces provided in this
Question-Answer Book. Do not write in the margins.
9 /7
Answers written in the margins will not be marked. 10 /6
(5) Graph paper and supplementary answer sheets will be
11 /6
provided on request. Insert the information required, mark
the question number box, and fasten them with string Total / 84
INSIDE this Question-Answer Book.

(6) No extra time will be given for inserting your information

or filling in the question number boxes after the ‘Time is
up’ announcement.

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Section B: Answer ALL questions. Parts marked with * involve knowledge of the extension
component. Write your answers in the spaces provided.

*1 Inside a room in which the air pressure is p0, Paul fills exactly half of a glass with water,
and then covers the glass with a plastic plate of negligible mass (Figure 1.1). Then he
carefully turns the glass and the plastic plate upside down. Some water leaks out in the
process but the plastic plate does not fall (Figure 1.2). Let p be the air pressure inside the
glass above the water surface. The height and the cross-sectional area of the glass is h and
A respectively. The area of the plastic plate is 2A. Assume that the air temperature inside
the glass remains unchanged throughout the process. The plastic plate does not exert any
force on the glass.

Answers written in the margins will not be marked.

plastic plate of
area 2A

h
2 air pressure inside = p
h water
2

glass of cross-sectional
area A
Figure 1.1 Figure 1.2

mg
(a) Show that p0 – p = , where m is the mass of the water. (2 marks)
A

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(b) Take p0 = 101 kPa, h = 10.0 cm, m = 0.250 kg and A = 50.0 cm2.
(i) What is the final volume of the air inside the glass? (3 marks)

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(ii) Estimate the volume of the water that has leaked out. (1 mark)

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2 You are given two identical cylindrical containers P and Q with removable caps as shown
in Figure 2.1, a hot water bath kept at 85 C, an ice-water bath and a data-logger
connected to a computer. The containers have temperature sensors fitted on the centre of
their bases. Describe how you would demonstrate that heat transfer by conduction in air is
much slower than heat transfer by convection in air. State your expected observations.
(6 marks)

removable cap

sealed opening

to data-logger

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cylindrical cylindrical
container P container Q
Figure 2.1

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3 A student sets up a friction-compensated runway. When a trolley runs down such a

runway, the friction acted on it by the runway is balanced by other forces and it travels
with a constant speed. He then pushes two trolleys X and Y towards each other on the
runway to make them collide, as shown in Figure 3.1. The motions of the trolleys are
recorded by two motion sensors (NOT shown in figure) installed at both ends of the
runway.
X
Y

friction-compensated
runway

Figure 3.1

Answers written in the margins will not be marked.

(a) The student finds that the total momentum of the trolleys after the collision is
significantly different from that before it. Briefly explain why. (2 marks)

(b) Suggest ONE way to modify the experiment so that the change in total momentum
during collision is minimized. (1 mark)

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(c) After modifying the set-up according to the answer of (b), the experiment is
repeated and the following velocitytime graphs are obtained. The velocity is taken
to be positive when the trolley is moving away from the motion sensor.

1.5 X

1.0

velocity (m s1)
Y

0.5

0
1.2 1.4 1.6 1.8
time (s)
0.5

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Figure 3.2

(i) Estimate the ratio of the mass of X to the mass of Y. (2 marks)

(ii) From Figure 3.2, determine the type of collision. Explain briefly. (2 marks)

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*4 Mercury is the innermost planet while Neptune is the outermost planet in the Solar system
(Figure 4.1). Mercury is 5.79  107 km away from the Sun. Its orbital period is 88.0 days.
Neptune is 4.50  109 km away from the Sun. Assume that both Mercury and Neptune
perform uniform circular motion with the Sun as the centre. Neglect the interaction
between Mercury and Neptune.

4.50  10 km
9
Neptune

Mercury

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5.79  10 km
7
Sun

Diagram NOT drawn to scale

Figure 4.1

(a) What provides the centripetal force for Mercury? (1 mark)

(b) Estimate the angular speed of Mercury. (1 mark)

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(c) Estimate the gravitational field strength of the Sun at Mercury’s orbit. (2 marks)

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(d) Estimate the period of Neptune in years.
(Given: 1 year = 3.16 × 107 s) (4 marks)

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5 A car travels up a slope along a straight road at a constant speed of 15 m s1 as shown in
Figure 5.1. The slope makes an angle of 5 to the horizontal. The mass of the car is
1200 kg. Figure 5.2 shows how the power output of the car’s engine varies with time.

power / kW

27
15 m s1

5 time / s
0 10

Figure 5.1 Figure 5.2

(a) What is the mechanical energy gained by the car from t = 0 to t = 10 s? (3 marks)

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(b) What is the energy output of the car’s engine from t = 0 to t = 10 s? (1 mark)

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(c) What is the sum of resisting forces (such as air resistance) acting on the car from
t = 0 to t = 10 s? (3 marks)

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(d) Then the car stops on the slope as shown in Figure 5.3. Its centre of gravity is at
point C. A and B are the contact points between the tyres and the slope. Find the
magnitude of the normal reaction N1 acting on A by the slope. (2 marks)

N1 N2

B 5
A

0.6 m 0.9 m
mg

Figure 5.3

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6 In a convenience store, Snowden, who is 1.8 m tall, stands between a wall and a goods
shelf (Figure 6.1). The goods shelf is 2.4 m tall, 0.4 m thick and is placed 2 m from the
wall. A plane mirror is mounted on the wall 3 m above the ground with an angle 45 to
the vertical.

wall

45 mirror

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Snowden
1m

1m
goods shelf

Figure 6.1

(a) Draw the images of the wall and Snowden in the mirror in Figure 6.1. (2 marks)
(b) Mary, the shopkeeper, stands 2 m to the right of the centre of the shelf. Her eyes are
1.4 m above the ground. In Figure 6.1, draw an eye and the path of a light ray to
show how Mary sees Snowden’s head. (3 marks)
(c) If Snowden looks up to see the mirror, can he see Mary’s image in the mirror?
Explain briefly. Neglect the distance between Snowden’s eyes and the top of his
head. (2 marks)

(d) Mary sits down and her eyes are 1 m above the ground. She cannot see Snowden’s
image as it is blocked by the shelf. What is the minimum distance from the wall at
which she can just see the Snowden’s image while sitting? (1 mark)

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7 Read the following article about the Global Positioning System (GPS) and answer the
questions that follow.

The Global Positioning System (GPS) is a system for navigation. It can provide one’s
position and a time reference accurately anywhere on the Earth.

The GPS contains a minimum of 24 satellites which revolve around the Earth twice
every day in 6 circular orbits of radii 26 550 km (Figure 7.1). They are controlled by
ground stations and transmit microwave signals to broadcast their changing positions
at different time instants. Users then can receive signals from the satellites and use
them to calculate their precise positions on the Earth (Figure 7.2).

Answers written in the margins will not be marked.

satellites

user

ground station

Figure 7.1 Figure 7.2

(a) Two GPS satellites, A and B, revolve in the same circular orbit around the Earth.
Both satellites emit a signal of frequency 1575.42 MHz (1 MHz = 106 Hz) at the
same instant when Leon is walking on a beach with his phone. After time intervals
6.77 × 10–2 s and 7.51 × 10–2 s, Leon’s phone receives the signals from satellites A
and B respectively.
(i) Find the wavelength of the microwave signals. (2 marks)

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(ii) Estimate the distances between Leon and the two satellites. (2 marks)

(iii) Leon is on the plane of the circular orbit. Locate his approximate position on
Figure 7.3 by sketching two appropriate circles. (2 marks)

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B

Earth

26550 km

Figure 7.3

(b) Suggest ONE reason why ultrasound is NOT suitable for transmitting signals in a
GPS system. (1 mark)

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(c) Leon walks from P to Q along a curved path. His phone records his positions at
several different instants during the journey as shown in Figure 7.4.

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Figure 7.4

Describe how his phone can estimate the average speed of his whole journey using
these data. (3 marks)

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8 A student connects two identical bulbs X and Y of resistance 60 Ω in parallel to a 3-V

battery, as shown in Figure 8.1. Switch S can turn on or off the lamps. When switch S is
open, the voltmeter shows a reading of 3.00 V. When switch S is closed, the voltmeter
reading drops to 2.95 V.
X

S
V

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3V

Figure 8.1

(a) Explain why the voltmeter reading drops when switch S is closed. (1 mark)

(b) (i) Find the equivalent resistance of the two bulbs. (2 marks)

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(ii) Find the total power output of the two bulbs when switch S is closed.
(2 marks)

*(c) In Figure 8.2, the two bulbs are now connected in parallel to the 220-V a.c. mains

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via a transformer with 150 turns in its secondary coil. The efficiency of the
transformer is 90.0%.

Ns = 150

~
220 V S
a.c.

Figure 8.2

(i) Find the number of turns in the primary coil if it is desired that the output
voltage of the transformer is 3 V. (2 marks)

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(ii) Find the input power of in the transformer if the total power output of the
two bulbs is the same as that in (b)(ii). (1 mark)

(iii) Find the peak current in the primary coil. (3 marks)

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9 + parallel metal plates

5 mm
–

Figure 9.1

In Figure 9.1, two parallel metal plates are placed 5 mm apart in a vacuum. Each plate has
an area of 1000 cm2. The top plate carries charge 2.00 × 10–8 C and the bottom plate
carries charge –2.00 × 10–8 C.

(a) Sketch the electric field set up between the parallel plates in Figure 9.2. Exclude
the region near the edges. (1 mark)

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+

Figure 9.2

(b) (i) An electron placed between the parallel plates experiences a force of
3.62 × 10–15 N. Find the electric field strength between the plates. (2 marks)

*(ii) Find the potential difference between the plates. (1 mark)

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*(c) A uniform magnetic field pointing into the paper is set up between the parallel
plates as shown in Figure 9.3. An electron enters the empty space between the
plates with a speed 1.6 × 107 m s–1. The weight of the electron is negligible.

+
× × × × × × × × × × ×
e
× × × × × × × × × × ×
–

Figure 9.3

(i) Draw the free-body diagram for the electron. (1 mark)

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(ii) If the velocity of the electron remains unchanged when it passes through the
parallel plates, find the magnetic field between the plates. Neglect the Earth’s
magnetic field. (2 marks)

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10
× × × × × × ×
v
Q P
× × × × × × ×

R S × × × × × × ×
10 cm

× × × × × × ×

Figure 10.1

In Figure 10.1, an external force (not shown) is applied to move a conducting square coil
of length 10 cm into a uniform magnetic field of 0.6 T pointing into the paper. The coil
moves with a constant velocity v = 2 cm s–1 towards the right. The total resistance of the

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coil is 2 .
(a) *(i) Find the induced e.m.f. ε in the coil. (2 marks)

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(ii) Determine the direction of the induced current in the coil. (1 mark)

*(iii) By (i), find the size of the induced current I in the coil. (1 mark)

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(b) Find the work done on the coil by the external force. Express your answer in terms
of ε and I. (2 marks)

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11 Lead-210 ( 210
82 Pb) is a beta emitter of half-life 22.3 years and can be found in very small

amounts in cigarettes. Most of it will be stored in the smoker’s body for his/her whole life.
It decays to form bismuth (Bi), which further decays to form polonium-210 (Po-210) as
shown in the equation below:
t 1 = 22.3 years t 1 = 5 days
2 2
210 210
82 Pb Bi Po

Polonium-210 is an alpha emitter.

(a) Write a nuclear equation for the decay of lead-210 into bismuth. (1 mark)

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*(b) The half-life of lead-210 is 22.3 years. (Given: 1 year = 3.16  107 s)
(i) Find the decay constant of lead-210. (1 mark)

(ii) Assume 3.20  10–17 mole of lead-210 is found in one cigarette. Calculate the
activity of lead-210 in one cigarette. (2 marks)

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(c) (i) Polonium-210 in cigarettes poses a serious health risk to smokers. Suggest
ONE reason. (1 mark)

(ii) The health risk in (i) lasts for many years even after a smoker stops the habit
of smoking. Explain why. (1 mark)

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END OF PAPER

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