# WORKSHEET ON THERMAL PHYSICS

```AIS, Male’
Grade 9 | First Term | 2018
Name: ………………………..
Class:……………
WORKSHEET ON THERMAL PHYSICS
1. The table shows the increase in length of four metals when heated through the same
temperature rise. Each metal initially has the same length.
A bimetallic strip is made from two of the metals. When heated, it bends in the direction
shown.
Which metals produce the above effect?
2. Density changes are responsible for which method of thermal energy transfer?
A. Conduction only
B. Convection only
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
3. At regular intervals along a railway line there is a gap between the rail sections.
What is the reason for the gap between the rail sections?
A. to allow for expansion of the rail sections during hot weather
B. to allow for vibrations of the rail sections as the train passes over them
C. to allow rain water to drain from the rail sections
D. to allow rain water to drain from the rail sections
4. The diagrams show a bimetallic strip when it is at room temperature and after it has been
cooled.
The change in shape occurs because
A. brass contracts more than invar.
B. brass expands when it cools down.
C. invar and brass contract by equal amounts.
D. invar contracts more than brass.
5. A person cannot unscrew the lid of a pot of jam. He finds that the lid can be unscrewed after
ithas been held under hot, running water for a
few seconds.
Why is this?
A.
B.
C.
D.
The air pressure in the jar falls.
The glass expands.
The jam melts.
The lid expands.
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
6. An axle is too large to fit into the hole in a wheel that is made of the same metal.
How can the axle be made to fit into the hole?
A. by cooling the axle alone
B. by cooling the wheel alone
C. by cooling both the axle and the wheel
D. by heating both the axle and the wheel
7. The diagrams show four identical cans with their outside surfaces painted either dull black
orpolished silver. Each can contains the same volume of water, initially at 80 °C After five
minutes in a cool room, which can contains the coolest water?
8. A student needs a double-walled glass vessel to contain a hot liquid.
What reduces heat losses by radiation?
A.
B.
C.
D.
a vacuum in the space between the walls
painting surface Q black
painting surface R black
painting surface S silver
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
9. A double-glazed window has two sheets of glass separated by a layer of air.Thermal
energy is conducted and convected through the layer of air. The amount of
conductionand convection varies with the thickness of the layer of air, as shown in the
graph.
Which thickness of air produces the smallest energy transfer, and why?
A.
B.
C.
D.
0.5 cm because there is little convection
1.0 cm because the total thermal energy transfer is least
1.5 cm because the total thermal energy transfer is small and conduction is low
2.0 cm because there is little conduction
10. The heat from the hot water in a metal radiator passes through the metal and then
What are the main processes by which the heat is transferred through the radiator and then
11. What makes a liquid-in-glass thermometer sensitive to a small change of temperature?
A. a bulb with a thin glass wall
B. a shiny liquid in its bore
C. a stem with a thick glass wall
D. a very narrow bore
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AIS, Male’
12.
Grade 9 | First Term | 2018
A thermocouple thermometer is made from two wires connected to a voltmeter.
Which arrangement gives a reading on the voltmeter?
13. A thermocouple thermometer uses a voltmeter to measure the e.m.f. generated between
twojunctions. The junctions are at temperatures t1 and t2. To calibrate the thermometer,
fixed pointsare needed.
What are the values of t1 and t2 when the thermometer is calibrated at the steam
Physics | worksheet thermal physics
point?
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AIS, Male’
Grade 9 | First Term | 2018
14.
The sensitivity of a liquid-in-glass thermometer depends on the volume of liquid used
and thediameter of the bore of the thermometer. Which changes will produce the greatest
increase in sensitivity?
15.
Four mercury-in-glass thermometers are made with different dimensions.
Which will have the greatest sensitivity?
A. 10 cm long and bore 0.75 mm wide
B. 15 cm long and bore 0.50 mm wide
C. 25 cm long and bore 0.10 mm wide
D. 30 cm long and bore 0.25 mm wide
16. In a vacuum flask, which methods of heat transfer are prevented by the vacuum?
A. conduction only
B. convection only
C. conduction and convection only
17. What happens when a metal bar is heated?
A. the distance between the molecules increases, making the bar longer
B. the molecules get larger, making the bar longer
C. the molecules vibrate quickly, making the bar denser
D. the speed of the molecules increases, making the bar thinner
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
18. The filings for a hole in a tooth should be made from a material that
A. expands more than the hole in the tooth
B. expands by the same amount as the hole in the tooth
C. expands less than the hole in the tooth
D. Does not expand when heated.
19. Fibre is used for home insulation in a cold country, as shown in the diagram.
Heat cannot easily escape through the ceiling because the fibre
A. traps air.
B. is warm.
C. is tightly packed.
D. heats the roof space.
Specific heat capacity
1. A 2 kg mass of copper is heated for 40 s by a heater that produces 100 J / s.
The specific heat capacity of copper is 400 J / (kg K).
What is the rise in temperature?
A 5K
B 10 K
C 20 K
D 50 K
2. A pupil adds 37g of ice at 0°C to 100g of water at 30°C. The final temperature of the water
and melted ice is 0°C. No heat is lost to, or gained from, the surroundings.
The specific heat capacity of water is 4.2J /(g°C).
What is the specific latent heat of ice?
A 47J /g
B 341J / g
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C 4700J / g
D 12600J / g
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AIS, Male’
Grade 9 | First Term | 2018
3. The heat capacity of an object, of mass 2.0kg, is C.
The energy needed to
A increase the temperature of the whole object by ∆t is C∆t.
B increase the temperature of unit mass of the object by ∆t is C∆t.
C melt the whole object is C.
D melt unit mass of the object is C.
4. An electric shower takes in cold water at 17°C. The shower gives 6000J of energy every
second to the cold water and heats it to 37°C. The specific heat capacity of water is 4200J
/(kg°C). What is the mass of hot water supplied by the shower in one second?
A 0.035kg
B 0.039kg
C 0.071kg
D 0.084kg
5. What is latent heat of vaporisation?
A the energy required to make molecules expand
B the energy required to make molecules expand and move apart
C the energy required to make molecules move apart
D the energy required to make molecules move faster
6. An insulated beaker contains 300g of water, initially at 30°C. Water at 100°C is added until
the temperature of the mixture reaches 50°C. The specific heat capacity of water is 4.2J
/(g°C). How much water is added?
A 60g
B 120g
C 180g
D 750g
Specific latent heat
1. Thermal energy is transferred to a solid. First it melts and then it boils to produce a gas.
Which statement about the temperature is correct?
A When melting and boiling the temperature does not change.
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AIS, Male’
Grade 9 | First Term | 2018
B When melting and boiling the temperature increases.
C When melting the temperature increases but when boiling the temperature stays the same.
D When melting the temperature stays the same but when boiling the temperature increases.
2. Steam at 100°C is passed into some water in a beaker. All the steam condenses in the water.
The mass of water in the beaker rises from 120.0g to 122.0g. The specific latent heat of
vaporisation of water is 2250J /g.
How much thermal energy is lost by the steam as it condenses?
A 8.9 × 10–4 J
B 1.1 × 103 J
C 4.5 × 103 J
D 2.7 × 105 J
3. Using an electric kettle, 200g of water at 100°C is converted into steam at 100°C in 300
seconds. The specific latent heat of steam is 2250J / g.
What is the average electrical power used?
4. Ice at –10°C is heated until it is water at +10°C. Which graph shows how the temperature
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
changes with time?
5. An ice cube, at a temperature of 0 °C, has a mass of 10 g.
The specific latent heat of fusion of water is 3 × 105 J / kg.
How much heat energy is needed to convert the ice cube into 10g of water at 0 °C?
A 30J
C 3 × 104 J
B 3000J
D 3 × 106 J
6. An ice-cube has of mass of 7.50g. The ice-cube is at 0°C. Heat from the surroundings reaches
the ice-cube at an average rate of 1.25J / s. How long does it take for all of the ice to melt?
(specific latent heat of fusion of ice = 333J / g)
A 35.5s
B 55.5s
C 2000s
D 3120s
THEORY QUESTIONS
1. Fig. below shows equipment placed on top of a house that uses solar energy to produce
hotwater
(a) Explain why the solar collector has a black base.
(b) State and explain why the hot water in the solar collector travels to the hot-water tank.
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AIS, Male’
Grade 9 | First Term | 2018
(c) Fig. above does not show any insulation.
(i) Explain why it is important to insulate the hot-water tank.
(ii) Explain how the hot-water tank is insulated.
2. Fig. below shows a metal pan containing water on a cooker. The hotplate heats the water.
(a) (i) State the method of heat transfer through the metal pan.
(ii) Describe how the molecules transfer heat through the metal pan.
(iii)At point X draw an arrow to show the direction of movement of molecules. Explain
Physics | worksheet thermal physics
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AIS, Male’
Grade 9 | First Term | 2018
3. A beaker contains 60 g of a hot substance, initially in the liquid state. Fig. 4.1 shows how the
temperature of the substance changes with time t as it cools in a laboratory.
(a) Use Fig. 4.1 to determine the melting point of the substance.
..............................................................................................................................................
(b) The specific heat capacity of the liquid is 1.7 J / (g °C). Calculate the loss of thermal
energy (heat) from the liquid between t = 0 and t = 20 s.
loss of thermal energy = .........................................
(c) Between points A and B on Fig. 4.1, the temperature is constant as the substance
changes from liquid to solid.
(i) Explain why the temperature stays constant, even though thermal energy is lost by
the substance.
..........................................................................................................................................
.........................................................................................................................................
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AIS, Male’
Grade 9 | First Term | 2018
(ii) Describe the change in the arrangement of the molecules as the substance changes
from a liquid to a solid.
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4. (a) In an experiment to measure the specific heat capacity of water, an electric heater heats
water in a glass beaker. The temperature of the water is measured at regular intervals of
time.
Fig. 5.1 shows how the temperature varies with time t.
(i) Use Fig. 11.1 to determine the change in temperature between
t = 0 and t = 100 s,
change = .................................................................
t = 100 s and t = 200 s.
change = .................................................................
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AIS, Male’
Grade 9 | First Term | 2018
(ii) State and explain why the values in (i) are different.
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(iii) Describe and explain what happens to the water if the heating is continued.
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(b) (i) The experiment in (a) is repeated using 72 g of water. The heater supplies 7400 J of
thermal energy (heat) to the water and the temperature rise of the water is 23 °C.
Calculate the specific heat capacity of water.
specific heat capacity = ..........................................
(ii) A bullet of mass 72 g is fired from a gun at a speed of 450 m / s.
Calculate the kinetic energy of the bullet.
energy = .................................................................
(iii) The amount of internal energy gained by the water and the amount of kinetic
energy gained by the bullet are approximately equal.
Describe the change in the motion of the molecules of the water and of the
molecules of the bullet that this addition of energy has caused.
water:
................................................................................................................................
........................................................................................................................................
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AIS, Male’
Grade 9 | First Term | 2018
bullet:
.......................................................................................................................................
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(c) A thermocouple is used in the experiment in (a). In the space below, draw a labelled
diagram of a thermocouple thermometer. Show clearly the part of the thermocouple
that is placed in the water in this experiment.
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