Belilios Public School
Half-yearly Examination, 2015-2016
Physics
Question Book
Secondary 3
Name: ____________________ (
)
Time Allowed: 1 hour and 15 minutes
Maximum marks: 100
Date: 13 January 2016
INSTRUCTIONS
1. This paper consists of TWO sections: Section A (39 marks) and Section B (61 marks). Answer
ALL questions in each section.
2. Section A consists of multiple-choice questions in this Question Book, while Section B contains
conventional questions printed separately in the Question-Answer Book.
3.
4.
5.
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 the 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.
Unless otherwise specified in the question, numerical answers should be either in exact value
or correct to three significant figures.
The diagrams in this paper are NOT necessarily drawn to scale.
INSTRUCTIONS FOR SECTION A (MULTIPLE-CHOICE QUESTIONS)
1. Read carefully the instructions on the Answer Sheet.
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 clean 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.
There are 26 questions in this section.
Section A:
Multiple Choices (39 marks)
1.
To which of the following scales does a temperature scale of 5°C to 36°C correspond?
A.
B.
C.
D.
2.
3.
From 273 K to 304 K
From 5 K to 36 K
From 278 K to 309 K
From 250 K to 281 K
The colours of some special substances change with temperature. Which of the following
thermometers makes use of this property to measure temperature?
A
Rotary thermometer
B
Thermistor thermometer
C
Infra-red thermometer
D
Liquid crystal thermometer
Which of the following thermometers can be used to measure the temperature inside an oven
which is about 800 °C?
4.
5.
A
Alcohol-in-glass thermometer
B
Liquid crystal thermometer
C
Mercury-in-glass thermometer
D
Resistance thermometer
When the temperature of a metal block increases,
A
the size of its particles increases.
B
its particles move more vigorously.
C
the average kinetic energy of its particles remains unchanged.
D
the number of its particles increases.
Gill uses the following portable gas stove to prepare hot pot. The energy supplied by the stove
in 1 hour is 1920 kcal. For how long does he need to wait if 5150 kJ is required to boil water?
(Given: 1 kcal = 4.19 kJ)
A
0.320 hour
B
0.640 hour
C
1.56 hours
D
11.2 hours
Page 1
6.
Which of the following graphs is the calibration curve for a liquid-in-glass thermometer if the
liquid expands linearly?  is the length of the liquid inside the tube of the thermometer and T is
the temperature of the liquid.
7.
8.
A.
C.
B.
D.
An immersion heater of power 1.50 kW is switched on for 10 minutes. How much energy is
given out by the heater?
A
150 J
B
900 J
C
15 kJ
D
900 kJ
A metal block of mass 5 kg is supplied with 36 kJ of energy. Its temperature rises from 30 °C to
60 °C. What is the heat capacity of the block in J °C–1?
A
30
B
2400
C
1200
D
6000
Page 2
9.
A heater supplies 1000 J of energy to a 5-kg metal block. The temperature of that metal block
rises from 25 °C to 35 °C. Assume that there is no energy loss to the surroundings. What is the
specific heat capacity of the metal block?
A
20 J kg–1 °C–1
B
50 J kg–1 °C–1
C
100 J kg–1 °C–1
D
200 J kg–1 °C–1
10. “Water has a specific heat capacity of 4 200 J kg–1 °C–1.” According to this statement, which of
the following is correct?
A.
B.
0.5 kg of water needs to absorb 2 100 J energy to decrease 1°C in temperature.
0.5 kg of water needs to lose 4 200 J energy to the surroundings to decrease 1°C in
temperature.
1.0 kg of water needs to lose 4 200 J energy to the surroundings to increase 1°C in
temperature.
1.0 kg of water needs to absorb 4 200 J energy to increase 1°C in temperature.
C.
D.
11. Which of the following statements is / are correct?
The unit of heat capacity is J kg –1 °C –1.
Specific heat capacity measures the temperature variations when 1 J of energy is
absorbed.
The unit of specific heat capacity is J kg–1 K –1.
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
(1)
(2)
(3)
A.
B.
C.
D.
12. Which of the following is a unit of power?
A
J s–1
B
kW h
C
kW h–1
D
J
13. An immersion heater takes 5 minutes to raise the temperature of 2 kg of water by 10 °C. How
long will it take for the same heater to raise the temperature of 3 kg of water by 5 °C?
A
2.50 minutes
B
3.33 minutes
C
3.75 minutes
D
6.67 minutes
Page 3
14. Two identical foam cups, A and B, carry different amounts of water at 20 °C initially. The mass
of water in cup A is twice as much as that in cup B. Water in both cups is heated by two
identical heaters respectively for the same period of time. Assume all the energy given out by
the heaters is absorbed by the water in the cups. If the final temperature of water in cup A is 50
°C, find the final temperature of water in cup B.
A
25 °C
B
35 °C
C
65 °C
D
80 °C
15. 0.2 kg of water at 70 °C is mixed with 1 kg of water at 10 °C. Find the final temperature of the
mixture. Assume that no energy is lost to the surroundings.
A
20 °C
B
30 °C
C
40 °C
D
50 °C
16. A 0.2-kg aluminium block is heated by a flame. The block is then quickly put into a polystyrene
cup containing 1 kg of water at 20 oC. If the final temperature of the water is 60 °C, find the
temperature of the block just before it is put into the water.
(Specific heat capacity of aluminium = 900 J kg−1 °C–1,
specific heat capacity of water = 4200 J kg−1 °C–1)
A
467 °C
B
512 °C
C
933 °C
D
993 °C
17. John heats 1 kg of soup from 25°C to 70°C for 15 minutes by a heater. How long does the same
heater take to heat 1.5 kg of the same kind of soup from 20°C to 80°C? The energy output per
unit time by the heater is a constant.
A.
B.
C.
D.
25 minutes
45 minutes
30 minutes
60 minutes
Page 4
18. An immersion heater of output power P is used to find the specific heat capacity of a liquid. The
following graph shows the temperature against time needed in heating m kg of the liquid. In the
same graph, the temperature variation curve for heating m kg of water using the same heater is
also shown. Find the specific heat capacity of the liquid. Given that the specific heat capacity of
water is 4 200 J kg–1 °C–1.
65
55
t
A.
B.
C.
D.
time/s
5 600 J kg–1 °C–1
2 050 J kg–1 °C–1
334 kJ kg–1 °C–1
Cannot be determined as the power P, the mass m and the time t are not given.
19. The following graph shows the temperature and time needed when an immersion heater of
unknown output power is used to heat 0.2 kg of water. Which of the following pairs of readings
is correct when a joulemeter is connected to the heater in the process? Given that the specific
heat capacity of water is 4 200 J kg–1 °C–1.
A.
B.
C.
D.
Initial reading is 10 000 J and final reading is 35 000 J.
Initial reading is 12 000 J and final reading is 54 000 J.
Initial reading is 9 000 J and final reading is 13 500 J.
Initial reading is 8 000 J and final reading is 13 000 J.
Page 5
20. The following setup is used to find out the heat capacity of water. Which of the following
actions will not help in increasing the accuracy of the result.
A.
B.
C.
D.
Use a stirrer to stir the water frequently.
Use a polystyrene lid for the cup.
Use a polystyrene cup instead of the beaker to work as the container.
Use a water bath outside the beaker to keep the temperature constant.
21. When measuring the specific heat capacity of a metal block, the value of specific heat capacity
founded is usually higher than the expected value. Which of the following statements is / are the
possible explanation(s)?
(1)
(2)
(3)
A.
B.
C.
D.
Some energy is lost to the surroundings.
More energy is absorbed by the metal block from the surroundings.
The cotton wrapping the block increases the energy lost to the surroundings.
(1) only
(3) only
(2) and (3) only
(1), (2) and (3)
22. Which of the following statements is / are incorrect?
(1)
(2)
(3)
A.
B.
C.
D.
Water is used as a coolant in car engines because it has a high specific heat capacity.
Heat flows from cold objects to hot objects when they are put in contact. This process
will stop when there is no temperature difference between them.
In coastal areas, the climate is more moderate than the interior land because of the high
specific heat capacity of the land.
(1) only
(2) only
(1) and (2) only
(2) and (3) only
Page 6
23. The following map shows four cities E, F, G and H. John
wants to experience an extreme temperature ranges within a
day. To which city John should go?
A.
B.
C.
D.
E
F
G
H
24. Which of the following statements is / are correct?
(1)
(2)
(3)
A.
Heat flows from hot objects to cold objects.
When two objects are in thermal equilibrium, they have the same temperature.
When crunched ice is added into a cup of warm water, all ice must melt immediately.
(1) only
B.
C.
D.
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
25. 5 g of ice at 0 °C melts to water at 0 °C. Find the energy absorbed by the ice.
(Given: specific latent heat of fusion of ice = 3.34 × 105 J kg–1)
A
1670 J
B
16 700 J
C
167 000 J
D
1 670 000 J
26. Which of the following quantities should be made use of to find out the energy released as
steam at 100 °C changes to water at 0 °C?
(1) Heat capacity of water
(2) Latent heat of vaporization of water
(3) Latent heat of fusion of ice
A
(1) only.
B
(2) only.
C
(1) and (2) only.
D
(1), (2) and (3).
End of Section A
Page 7
Belilios Public School
Half Yearly Examination, 2015-2016
Physics
Question-Answer Book
Secondary 3
Name: ____________________ (
Time Allowed: 1 hour and 15 minutes
Maximum marks: 100
Date: 13 January 2016
)
Section B: Structured Questions (61 marks)
 Answer ALL questions in this section.
 Write ALL your answers in this Question-Answer book.
 All workings must be shown clearly.
Question No.
1
2
3
4
5
6
7
Total
Max. Marks
5
4
11
11
7
12
11
61
Marks Scored
1
The resistance of the metal in a resistance thermometer is 300 Ω and 1500 Ω at 10 °C and 90 °C
respectively.
(a) What is the temperature when the resistance is 900 Ω?
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(b) What is the resistance of the metal when the temperature is 110 °C?
(1 mark)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(c) What is lowest possible temperature the thermometer can measure?
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
2
A 2-kW heater is completely immersed into a large tank of water. How much energy is
transferred to the water if it is switched on for 30 minutes?
(a) Express your answer in kW h.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(b) Express your answer in J.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 1
3
Kitty uses the apparatus shown below to find the specific heat capacity of a metal.
(a) How can the energy supplied by the heater be measured? Explain your answer with the aid
of a diagram.
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(b) Explain why a few drops of oil should be added into the holes for inserting the heater and
the thermometer.
(1 mark)
_______________________________________________________________________
_______________________________________________________________________
(c) Explain why the heater should not be switched on unless it is inserted into the metal block.
(1 mark)
_______________________________________________________________________
_______________________________________________________________________
Page 2
3
(d) The following data are obtained:
Mass of metal block = 1 kg
Initial temperature = 25 °C
Final temperature = 32 °C
Energy supplied by the heater = 6750 J
Calculate the specific heat capacity of the metal.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(e) The value obtained in (d) is found to be higher than the accepted value of the specific heat
capacity of the metal. Suggest a reason for this and explain your answer briefly. (2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(f) Suggest TWO methods to improve the accuracy of the experiment.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 3
4
Eileen is going to cook some vegetable. If she fries the vegetable, she will use 20 g of olive oil
and heat the oil to about 200 °C before putting the vegetable into the wok. If she boils the
vegetable, she will boil 1 kg of water and then add 10 g of olive oil before adding the vegetable
to the water. The output power of her stove is 2000 W.
(Given: Specific heat capacity of olive oil = 1970 J kg−1 °C−1
Specific heat capacity of water = 4200 J kg−1 °C−1)
(a) Suppose Eileen fries vegetable.
(i)
Find the energy required to heat up the oil from 27 °C to 200 °C.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(ii) If extra 300 kJ is required to cook the vegetable, how long will it take for the whole
cooking process?
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(iii) In practice, will Eileen use a longer time or a shorter time to cook? Why? (2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 4
4
(b) Suppose Eileen boils the vegetable.
(i)
How much energy is required to heat up water and oil from 27 °C to 100 °C?
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(ii) Which cooking method consumes more energy according to the above calculation?
Explain briefly.
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 5
5
In congee shops, there is a kind of beef congee that is the mixture of the hot congee and the fresh
beef. The fresh beef should be kept at a temperature of 2°C while the hot congee is at a
temperature of 99°C. The final temperature of the mixture is 95°C. The masses of the congee and
the beef are 0.4 kg and 0.05 kg respectively.
Given that the specific heat capacity of the congee is 4100 J kg−1 °C−1.
(a) Find the specific heat capacity of the beef.
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(b) Why should the fresh beef be kept at such a low temperature?
(1 mark)
_______________________________________________________________________
_______________________________________________________________________
(c) “If 99°C hot congee is poured onto the skin of a human, it is more dangerous than the hot
water of the same temperature.” Comment on this statement.
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 6
6
The graph shows the temperature (T) and time (t) relation of two objects A and B of the same
material. The masses of A and B are x kg and 2x kg respectively. The graph also shows the curve
of 1 kg of water. They are heated with the same heater for the same period of time. Given that the
specific heat capacity of water is 4 200 J kg–1 °C–1.
(a) From the graph, find the heat capacity of objects A and B.
(4 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(b) If x is 1, what is the specific heat capacity of objects A and B?
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 7
6
(c) Sketch a graph to show the curves of energy absorbed (E) against temperature difference
(∆T) of objects A and B.
(3 marks)
(d) “There is difficulty in comparing the ability of energy absorption of two materials by using
the quantity heat capacity.” Comment on this statement.
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Page 8
7
(a)
When a liquid is freezing, what is the change of the following quantities?
(i)
(4 marks)
The average potential energy of the particles
.
(ii) The average separation between the particles
.
(iii) The average kinetic energy of the particles
.
(iv) The internal energy of the object
.
(b) What is the physical meaning of specific latent heat of fusion of ice?
(3 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(c) A 1500 W immersion heater is used to heat some melting ice. It is found that 700 g of ice
melts after 3 minutes. Assume that no energy is lost to the surroundings. Find the specific
latent heat of fusion of ice.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(d) The literature value of the specific latent heat of fusion of ice is 3.34 × 105 J kg–1. Find the
percentage of energy lost to the surroundings.
(2 marks)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
End of Section B
End of Paper
Page 9
Belilios Public School
Half Yearly Examination, 2015-2016
S3 Physics
(Suggested Answers)
Section A: Multiple Choice (39 marks)
1. C
11. A
21. A
2. D
12. A
22. D
3. D
13. C
23. C
4. B
14. D
24. B
5. B
15. A
25. A
6. D
16. D
26. C
7. D
17. C
8. C
18. A
9. A
19. B
10. D
20. D
Section B: Structured Questions (61 marks)
1
(a)
Let T be the unknown temperature
1500 − 300 900 − 300
=
90 − 10
T − 10
T = 50°C
(b)
1M
1A
Let R be the unknown resistance
1500 − 300 R − 300
=
90 − 10
110 − 10
R = 1800 Ω
(c)
1A
The smallest resistance of the metal is 0 Ω, the corresponding temperature x is
the lowest possible temperature it can measure
1500 − 300 0 − 300
=
90 − 10
x − 10
x = −10°C
1M
(R = 0)
1A
2
(a)
E = (2)(0.5) = 1 kW h
1M+1A
(b)
E = (2000)(30)(60) = 3 600 000 J
1M+1A
-1-
3
(a) Connect the joulemeter, power supply and heater as shown below.
The difference between the initial and final readings of the joulemeter is the
energy supplied by the heater.
1A
joulemeter
immersion
heater
power supply
(Joulemeter/kilowatt-hour meter)
1A
(Heater, joulemeter and power supply connected correctly)
1A
(b) To ensure a good thermal contact between the heater/thermometer and the metal
block.
(c) To prevent damaging the heater due to overheating.
(do not accept “To reduce heat loss to the surroundings”)
(d) Specific heat capacity of the metal =
=
Q
m∆T
1A
1M
6750
1× (32 − 25)
= 964 J kg−1 °C−1
1A
1A
(e) Some energy is lost to the surroundings.
(f)
1A
As a result, the actual amount of energy absorbed by the metal block is less than
the energy supplied by the heater.
1A
Any TWO:
Place the metal block on a polystyrene tile.
1A
Wrap the metal block with cotton wool.
Completely insert the heater into the hole of the metal block
Record the highest temperature reached but not immediately after the power
supply is switched off
1A
1A
1A
4
(a) (i)
By Q = mc∆T,
1M
energy required = 0.02 × 1970 × (200 − 27) = 6820 J
1A
1M
(ii) By Q = Pt,
time for cooking =
Q
6820 + 300 000
=
= 153 s or 2.56 mins
P
2000
-2-
1A
(iii) In practice, Eileen will use a longer time to cook.
This is because energy is lost to the surroundings during cooking. (Or other
reasonable answers)
(b) (i)
1A
1A
By Q = mc∆T,
energy required
= 1 × 4200 × (100 − 27) + 0.01 × 1970 × (100 − 27)
1M
= 308 038 J
1A
(ii) Boiling the vegetable consumes more energy.
1A
This is because the specific heat capacity of water is very high
1A
and the amount/mass of water used in boiling is more than the amount/mass
of the oil used in frying.
1A
5
(a) Energy released by congee = Energy absorbed by beef
(0.4)(4100)(99 − 95) = (0.05)(c)(95 − 2)
∴ c = 1410.8 J kg−1 °C−1
(b) For the reason of hygiene, bacteria will be inhibited in low temperature.
(c) The statement is correct.
The specific heat capacity of the hot congee is slightly lower than that of the hot
water and hence the skin absorbed less energy from the hot congee. However,
since the congee is more viscous, it cannot flow easily from place to place. If it is
poured onto the skin, the small part of the skin absorbs large amount of
energy and it will cause a more harmful effect.
1M
1A
1A
1A
1A
1A
1A
6
(a) From the curve of water, energy supplied by the heater in 420 s
= mc∆T = (1)(4 200)(35 − 25) = 42 000 J
For A,
1A
E = mc∆T
42 000 = (xc)(65 − 25)
heat capacity of A = xc = 1 050 J °C−1
∴
For B,
42 000 = (2xc)(45 − 25)
heat capacity of B = 2xc = 2 100 J °C−1
∴
-3-
1M
1A
1A
(b) If x = 1, specific heat capacity of A and B
=
1M+1A
heat capcity of A
= 1 050 J kg−1 °C−1
x
(c)
1A
(Correct axes)
(2 straight lines passing through origin)
(slope of B larger than that of A)
1A
1A
(d) This statement is true because
heat capacity measures the energy absorbed per unit temperature change only.
It does not give information about the quantity of the mass. Thus in general, we
compare the ability of energy absorption of two materials by using specific heat
capacity.
1A
1A
1A
7
(a)
1A
1A
1A
1A
(i) decreases
(ii) decreases
(iii) remain unchanged
(iv) decreases
(b) Specific latent heat of fusion of ice is the energy needed
to change 1 kg of ice to water
without a change in temperature.
1A
1A
1A
(c) Energy supplied by heater = energy absorbed by ice
Pt = mlf
1M
1500 × 3 × 60 = 0.7 × lf
lf = 385714 J kg−1 or 3.86 × 105 J kg−1
∴ The specific latent heat of fusion of ice is 3.863 × 105 J kg−1.
(d) Actual energy absorbed by ice
E actual = ml f = 0.7 × 3.34 × 10 = 2338000 J
1A
1M
5
Percentage lost =
1500 × 3 × 60 − 233800
× 100% = 13.4 %
1500 × 3 × 60
-4-
1A