HKCEE / Phy I / Heat / P. 1
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Figure 1
Figure 1 shows an apparatus for investigating the relation between volume and
temperature of a gas under constant pressure. A fixed mass of nitrogen was trapped in a
graduated capillary tube of uniform bore by a small pellet of mercury. The temperature
of the liquid A can be adjusted by means of the electric heater or by the addition of
cooling mixture.
Figure 2
The length of the nitrogen column was measured at different temperature and the
readings obtained are indicated by the point shown in figure 2.
Using figure 2, obtain a value for the absolute zero of temperature. (1 mark)
(b) What conclusion can you draw on the relation between absolute temperature and
the volume of a fixed mass of the gas at constant pressure ?
(a)
(c)
(1 mark)
Would you choose a thick-walled or a thin-walled capillary tube for this
experiment ? Explain briefly.
(2 marks)
(d) Using your answer to (a), calculate the volume of nitrogen at 360 oC if it occupies
a volume of 1.5 cm3 when the temperature is 20oC, the pressure being constant.
(3 marks)
(e)
The atmospheric pressure was 760 mm Hg throughout the above experiment.
Obtain from figure 8 the length of the nitrogen column at 0 oC. What would this
length be if the atmospheric pressure during the time of the experiment was 750
mm Hg ?
(3 marks)
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(a)
Figure 2
Figure 2 shows the apparatus for investigating the relation between the pressure
and the volume of a gas at constant temperature. The initial readings of the syringe
and the Bourdon Gauge are respectively 15 ml and 10 5 N m-2.
(i)
If the syringe reading is reduced to 5 ml by applying force to the piston,
calculate the corresponding reading in the Bourdon Gauge.
Figure 1
(ii) The calculated reading of the Bourdon Gauge will be different from the
Figure 1 shows a mechanical model for the kinetic theory of a gas. As the ball
bearings are in motion, the mean separation between the piston and the base is h.
State how the value of h may be affected by
(i)
(ii) adding weights to the piston.
(b)
(iii) Explain in terms of the kinetic theory of matter, why at constant volume, a
change in the temperature of a gas causes a change in its pressure. (3 marks)
increasing the frequency of vibration of the base.
(iii) reducing the number of ball bearings.
observed reading. Suggest one reason to account for the difference. (4 marks)
(3 marks)
HKCEE / Phy I / Heat / P. 3
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Ice is add to a flask of water and the mixture well stirred. The temperature of the
mixture remain steady at 0oC and the masses of ice and water inside the flask are found
to be 0.3 kg and 1.2 kg respectively.
(a)
A burner is now used to heat the flask. If the mixture absorbs heat at a constant
rate, and the time required to melt the ice completely is T, what will be the
temperature of the mixture after another length of time T ?
(6 marks)
(b)
(i)
About 15 g of salt is then added to the water and the solution is boiled. What
can you say about the temperature of the mixture when about half the solution
has boiled away ?
(ii) Suppose salt were added to the water together with ice at the beginning of the
whole experiment (before any heating takes place). What effect would it have
on the steady temperature of the mixture of ice and water ?
(c)
(4 marks)
While the liquid in (b) (i) is still boiling, the burner is removed and the flask
immediately connected to a vacuum pump. Explain briefly what will happen to the
liquid a short time after the pump has started operating.
(5 marks)
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Figure 11 shows a simple solar heater.
Figure 11
(a)
(i)
Why should the inner wall of the heater and the surface of the pipe be
blackened ?
(ii) The heater is covered by a sheet of glass. Give one reason for this.
(iii) Suggest one material suitable for the lagging.
(4 marks)
(b) When water flows through the pipe in the solar heater at a rate of 0.01 kg s -1, its
temperature rises by 7oC.
(Specific heat capacity of water = 4200 J kg-1 K-1)
(i)
Find the power supply by the heater.
(ii) If the rate of flow were reduced to 0.04 kg s-1, find the increase in
temperature. Briefly comment on your answer.
(c)
(7 marks)
Draw a simple diagram to show a device different from that described in (a),
making use of solar energy and explain briefly how it works.
(4 marks)
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The following table represents data from an experiment showing the relationship of the
pressure and temperature of a fixed mass of a gas :
Temperature / oC
30
40
50
60
70
80
Pressure / kPa
97
100
103
106
109
112
(1 kPa = 105 N m-2)
(a)
Plot the pressure-temperature graph for temperature ranging from - 300 oC to 120
o
C and pressure ranging form 0 kPa. (You are recommended to use a scale of 1 cm
to represent 20oC and 1 cm represent 10 kPa.)
(b) What is the intercept of your graph on the temperature axis ?
(c)
(4 marks)
(2 marks)
If the Celsius temperature (oC) is converted to a temperature in a new scale by
adding the absolute value of the intercept to your obtained in (b), find the relation
between pressure and the new temperature from your graph.
(2 marks)
(d) If the pressure of the gas in the experiment were increased to 150 kPa, what would
be the temperature of the gas on the temperature scale you constructed in (c) ?
(2 marks)
(e)
Draw a diagram to show the experimental set-up you would use to obtain the
above data. State TWO precautions that should be taken in this experiment.
(5 marks)
HKCEE / Phy I / Heat / P. 6
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heater. The energy transferred through the heater is measured by a joulemeter. The
heater is switched on for 330 s and then switched off.
The variation of the temperature
of the liquid X with time is plotted in a graph shown in figure 6.
(a)
After the heater is switched off, the temperature of the liquid continues to rise for a
while and then falls again. Explain why.
(b)
(3 marks)
What is the maximum increase in temperature of liquid X in this experiment ?
(2 marks)
(c)
The initial and final readings of the joulemeter are 74050 J and 83770 J
respectively.
The mass of the liquid X is 0.2 kg . What is the specific heat
capacity of the liquid, as found from this experiment ? (Assume that the heat
capacity of the apparatus and the heat lost to the surroundings are negligible.)
Figure 5
(4 marks)
(d) Although the plastic cup is made of poor conducting material, some energy is still
lost to the surroundings. Should the result obtained in (c) be higher or lower than
the true value of the specific heat capacity of the liquid X ? Explain briefly.
(3 marks)
(e)
If a student forgets to cover the plastic cup with the lid, would he expect the
maximum increase in temperature to be higher than, equal to or lower than the
value obtained in (b) ? Explain briefly.
Figure 6
Figure 5 shows an experimental set-up to find the specific heat capacity of a liquid. The
liquid X, contained in the plastic cup, is heated from room temperature by an immersion
(3 marks)
HKCEE / Phy I / Heat / P. 7
8506
to or lower than the result you obtain in (c), if the experiment were repeated
Figure 7 shows an experiment set-up to determine the specific latent heat of fusion of
(i)
ice. The ice used is crushed and melting. In the left hand side, A, the electrical energy
(ii) using ice at -5oC ?
consumed by the heater is measured by a joulemeter. The water from the melted ice was
Explain briefly in each case.
collected in a beaker. In the right hand side, B, shows a control experiment of A set up
without electricity supply to the heater.
(a)
What is the purpose of the control experiment in B ?
(2 marks)
(b) Why should the ice used in the experiments be
(i)
crushed, and
(ii) melting ?
(4 marks)
Figure 7
(c)
Calculate the specific latent heat of fusion of ice from the following experimental
data :
Initial joulemeter reading
= 39 428 J
Final joulemeter reading = 50 328 J
Mass of water collected in A
= 0.04 kg
Mass of water collected in B
= 0.01 kg
(5 marks)
(d) Would you expect the latent heat of fusion of ice obtained to be higher than, equal
neglecting the control experiment ?
(4 marks)
HKCEE / Phy I / Heat / P. 8
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Figure 3
Figure 3 shows the apparatus which may be used to measure the specific heat capacity
of water.
(a)
Draw a simple diagram to show how the apparatus can be set up for the experiment.
(3 marks)
(b) The following are readings taken in the experiment :
(i)
The rating of the heater
= 12 V
40 W
Mass of water used
= 200 g
Initial temperature
= 25.1 oC
Final temperature
= 53.2 oC
Time taken to heat up the water
= 10 minutes
Given that the water is well-stirred throughout the experiment, calculate the
specific heat capacity of water as measured from the experiment.
(ii) Give two reason why a polystyrene cup should be used in the experiment.
(iii) Why should the water be stirred throughout the experiment ?
(c)
(7 marks)
Describe, with the aid of a diagram, a method to check whether the power output
of the heater is 40 W. Show how the actual power output of the heater can be
calculated.
(5 marks)
HKCEE / Phy I / Heat / P. 9
8704
Figure 1
A mercury thread is trapped in a uniform bored capillary tube which is used in an
experiment to verify Charles' law (see Figure 1.). The following data are recorded :
Temperature
20
30
40
50
60
70
80
136
140
146
152
156
160
166
 / oC
Length of air column
L / mm
(a)
Draw a diagram to show an experiment set-up and describe briefly the procedure
to obtain the above date.
(b) Name any TWO precautions in this experiment.
(c)
Plot a graph of L against  with  ranging from - 360oC to 110oC.
(d) What is the “absolute zero” as obtained from this experiment ?
(4 marks)
(2 marks)
(3 marks)
(2 marks)
(e)
What is the relationship among L,  and the "absolute zero" in (d) ?
(f)
How does the pressure of the trapped air in the tube change with temperature ?
(2 marks)
(2 marks)
HKCEE / Phy I / Heat / P. 10
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The specific heat capacity of water is 4 200 J kg-1 K-1
(a)
What does this statement mean ?
(2 marks)
(b) Describe briefly, with the aid of a diagram, an experiments to measure the specific
heat capacity of water.
(c)
(5 marks)
A kettle with 1.6 kg of water is placed on top of an electric heater at 1000 W. It
takes 14 minutes for the temperature of the water to increase from 20oC to 100oC.
Find
(i)
the energy released by the heater, and
(ii) the energy absorbed by the water
during that time.
Give TWO reasons to account for the difference of the value you obtained in (i)
and (ii).
(6 marks)
(d) It is known that the specific heat capacity of water is higher than most of the other
liquids. Name TWO practical importance of this in daily life.
(2 marks)
HKCEE / Phy I / Heat / P. 11
8804
Figure 4
Figure 4 shows a mechanical model of a gas. A large number of ball bearings are set in
motion by a vibrating platform. The ball bearings represent gas molecules.
(a)
Which property of the gas (pressure, volume or temperature) would
(i)
the weight of the disc
(ii) the voltage of the d.c. supply
represent in this model
(3 marks)
(b) For a fixed amount of gas, when temperature is kept constant, its pressure
increases as the volume decreases. Describe how this behavior of gas can be
demonstrated using the model. Describe the change in the average speed of the ball
bearings and the frequency of bombardment on the walls in this demonstration.
(6 marks)
(c)
In a real situation, gas molecules could keep on moving by themselves without an
external energy supply but in this model energy has to be supplied to the ball
bearings continuously by the vibrating platform. Briefly explain this difference.
(3 marks)
(d) A large polystyrene ball is now placed into the cylinder. Briefly describe and
explain the motion of the polystyrene ball.
(3 marks)
HKCEE / Phy I / Heat / P. 12
8904
Figure 5
Figure 5 shows an experiment done by a student to find the variation of pressure of air
inside a flask with temperature. The pressure Y and the temperature t are measured by
Bourdon Gauge and a thermometer respectively.
(a)
The following data are recorded in the experiment :
t / oC
20
35
45
60
78
90
100
Y /kN m-2
107
112.5
116
121.5
128
132.5
136
Using a scale that 4 cm represents 10 kN m-2 and 2 cm represents 10oC, plot a
graph of Y against t ranging from 0oC to 100oC.
(5 marks)
(b) Find the equation relating the pressure and temperature from the graph in (a).
(2 marks)
(c)
The flask is then transferred into a trough of oil and the gauge reading is 118 kN
m-2. What is the temperature of the oil ?
(2 marks)
(d) Give THREE suggestions to improve the experimental set up as shown in figure.
(3 marks)
(e)
Base on the kinetic theory of gases, explain briefly why the pressure increases as
the temperature does.
(3 marks)
HKCEE / Phy I / Heat / P. 13
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Figure 5
Figure 5 shows the cooling curve of a substance changing from liquid to solid state.
(a)
Given a boiling tube half filled with this substance in its solid state, describe, with
the help of diagram, an experiment to obtain the cooling curve of the substance.
(5 marks)
(b) Read from the above cooling curve the melting point of the substance.
(c)
(1 mark)
Explain why the temperature remains constant as the substance solidifies at its
melting point, even though heat is lost to the surroundings.
(2 marks)
(d) If the mass of substance used is 0.05 kg and the rate of heat loss to the
surroundings at its melting point is 25 W, find the specific latent heat of fusion of
the substance.
(3 marks)
(e)
Describe the arrangement and motion of the molecules of the substance in the
(i)
solid state, and
(ii) liquid state.
(4 marks)
HKCEE / Phy I / Heat / P. 14
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(ii) Suggest two methods to reduce the amount of carbon dioxide in the
atmosphere.
Figure 7
Figure 7 shows the apparatus of an experiment to study the absorption of solar energy
by gases. Identical flasks A and B are filled with carbon dioxide and air respectively.
They are placed under sunlight and their temperate are taken at 3-minutes intervals. The
results are as follows :
Time / minutes
0
3
6
9
12
15
18
Temperature in A / oC
28.0
38.4
44.0
46.2
47.8
48.8
48.8
Temperature in B / oC
28.0
37.8
41.8
43.7
45.2
46.0
46.0
(a)
Using a scale that 2 cm represents 5oC and 2 cm represents 3 minutes, plot the
temperature-time graphs for carbon dioxide and air on the same graph paper.
(5 marks)
(b) Why does each of the gases reach a steady temperature ?
(c)
(2 marks)
The mass of carbon dioxide in flask A is 0.00196 kg and the mass of air in flask B
is 0.00125 kg. The specific heat capacities of carbon dioxide and air are 640 J kg -1
K-1 and 740 J kg-1 K-1 respectively. Which flask of gas gains more energy to reach
its steady temperature ? Show your calculations.
(5 marks)
(d) Each year the amount of carbon dioxide in the atmosphere is increased by billions
of tons.
(i)
Suggest a possible effect on the mean temperature of the earth.
(3 marks)
HKCEE / Phy I / Heat / P. 15
9294
Figure 6
A student uses the experimental set-up shown in Figure 6 to find the specific heat
capacity of a metal. The cylindrical metal block is heated by an immersion heater of
unknown power. The following results are obtained :
(a)
Mass of metal block
= 1 kg
Initial temperature of metal block
= 29 oC
Final temperature of metal block
= 41 oC
Energy supplied by the heater
= 12300
Describe, with the help of a diagram, a method to measure the energy supplied by
the heater.
(b) Calculate the specific heat capacity of the metal.
(c)
J
(4 marks)
(2 marks)
The value obtained in (b) is found to be higher than the actual specific heat
capacity of the metal. Suggest a reason for this and explain your answer briefly.
(3 marks)
(d) Suggest TWO improvements on the set-up to increase the accuracy of the
experiment.
(e)
(3 marks)
Is the above method suitable for finding the specific heat capacity of wood ?
Explain briefly.
(3 marks)
HKCEE / Phy I / Heat / P. 16
9304
be affected ? Explain briefly.
(e)
Suggest TWO improvements on the set-up to increase the accuracy of the
experiment.
Figure 5
A student performs an experiment to find the specific latent heat of vaporization of
water. A beaker containing water is placed on an electronic balance. the water is heated
by a 100 W immersion heater, which is immersed in the water such that it does not
touch the beaker, as shown in Figure 5.
(a)
It is found that there is a slight decrease in the mass of water in the beaker before
the water boils. Explain briefly in terms of molecular motion.
(3 marks)
(b) When the water boils, the reading of the balance is taken. After 240 s, the reading
of the balance is taken again. The following results are obtained:
Initial reading of the balance = 525.4 g
Final reading of the balance = 515.2 g
Calculate
(i)
the energy supplied by the heater in 240 s,
(ii) the specific latent heat of vaporization of water.
(4 marks)
(iii) The value obtained in (b) (ii) is found to be higher than the actual specific
latent heat of vaporization of water. Suggest a reason for this and explain
briefly.
(3 marks)
(d) If the student covers the beaker with a lid, how would the result of the experiment
(3 marks)
(2 marks)
HKCEE / Phy I / Heat / P. 17
9404
Figure 7
Figure 8
A student uses the set-up shown in Figure 7 to study the relationship between the
pressure and volume of a fixed mass of gas at constant temperature. The piston is
pushed in or pulled out to vary the volume of gas and the corresponding pressure is
measured by the Bourdon gauge.
(a)
Volume V / m3
2.6×10
100
-4
Plot a graph of P against
and
2.10×10
120
-4
1.75 ×10
140
-4
1.50×10
160
-4
1.31×10-4
1
on graph paper, with P ranging from 0 to 160 kPa
V
1
ranging from 0 to 1000 m-3.
V
(5 marks)
(b) Should the rubber tubing be long or short ? Explain briefly.
State TWO other precautions that should be taken to improve the accuracy of the
experiment.
(4 marks)
Explain in terms of the kinetic theory of gases, the increase in the pressure of the
gas whet he volume decreases at a constant temperature.
(d)
kPa respectively. The piston is then completely pushed in and the reading of the gauge
the container.
What physical law is the student attempting to verify ?
(c)
a container. Initially the readings of the syringe and the gauge are 1.8×10-4 m3 and 100
becomes 210 kPa. Assume that temperature remains unchanged, calculate the volume of
The following results are obtained in the experiment :
Pressure P / kPa 80
The student uses another set of apparatus as shown in Figure 8 to measure the volume of
(3 marks)
(3 marks)
HKCEE / Phy I / Heat / P. 18
9506
Figure 1
Figure 1 shows a water heating system. The tank contains 15 kg of water. The heater is
switched on when the contacts are covered by water and the temperature of the water is
below 45oC.
(a)
The heater takes 5 minutes to raise the temperature of the water from 20oC to 45oC.
The specific heat capacity of water is 4200 J kg-1 K-1. Find
(i)
the energy used to heat up the water,
(ii) the output power of the heater.
(2 marks)
(2 marks)
HKCEE / Phy I / Heat / P. 19
(d) A teacher comments that the result of this’ experiment is not accurate. She points
9704
out that a control experiment is required in order to improve the accuracy of the
experiment.
*(i) Describe how the control experiment can be set up and explain its function.
(5 marks)
(e) After setting up the control experiment, the student repeats the above experiment.
Would you expect the specific latent heat of fusion obtained to be higher or lower
than that obtained in (b)? Explain your answer.
A student uses the apparatus shown in Figure 5 to perform an experiment to measure the
specific latent heat of fusion of ice. He uses a joulemeter to measure the energy required
to melt a certain amount of ice.
(a)
Draw a diagram to show how the apparatus can be set up for the experiment.
(3 marks)
(b) The following data are obtained in the experiment :
Initial joulemeter reading
Final joulemeter reading
= 28 000 J
= 40 400 J
Mass of water collected in the beaker
= 0.045 kg.
Calculate the specific latent heat of fusion of ice.
(3 marks)
(c)
(2 marks)
Why should the ice used in the experiment be crushed ?
(2 marks)
HKCEE / Phy I / Heat / P. 20
9902.
0.1 kg of melting ice is added to 0.5 kg water at 30 oC in a foam cup. Find the final
temperature of the mixture.
(Given :
Specific heat capacity of water = 4200 J kg-1 oC-1,
Specific latent heat of fusion of ice = 3.4 ×105 J kg-1)
HKCEE / Phy I / Heat / P. 21
9909.
(e)
David uses a larger flask B to replaced flask A and repeated the experiment.
The volume
of flask B is twice that of A. Assume the masses of the gas in
both flasks are the same.
(i)
Estimate the gas pressure in flask B at 0oC.
(2 marks)
(ii) On the same graph in (a), draw the graph of P against  you expect to
obtain in this experiment.
David uses the set-up shown in Figure 10 to study the relationship between the
pressure P and temperature  of a fixed mass of gas inside a flask A. The following
results are obtained :
Temperature  / oC
20
36
50
64
80
98
Pressure P / k Pa
102
109
111
115
124
129
(a)
Using a scale of 1 cm to 10 kPa and 1 cm to 10 oC, plot a graph of P against 
on graph paper, with P ranging from 0 to 200 kPa and  ranging from 0 to
100oC..
(4 marks)
(b) From the graph in (a), David concludes that
The pressure (in kPa) of the gas is directly proportional to its temperature (in
o
C).
Comment on David’s conclusion.
(c)
(2 marks)
State two precautions that should be taken to improve the accuracy of the
experiment.
(2 marks)
(d) Based on the kinetic theory, explain why the pressure of the gas increases
with temperature at a constant volume.
(4 marks)
(1 marks)