Transfer of Thermal Energy (Cambridge (CIE) IGCSE Physics)

Exam Questions

3 hours38 questions
1a1 mark

A student is investigating the rate of cooling of water under different conditions. A greater rate of cooling occurs if there is a greater change in the temperature during the same period of time.

  Fig. 3.1 shows some of the apparatus.

p2-3a

The thermometer in Fig.3.2 shows the room temperature θR at the beginning of the experiment. Record θR in °C.

p2-2aii

θR = ........................................................ 

1b4 marks

The student pours 200 cm3 of hot water into the beaker.

  She records the temperature θ of the hot water at time t = 0. She immediately starts a stopclock.

  She continues recording the time and the temperature readings every 30 s. The readings are shown in Table 3.1.

 

Table 3.1

Beaker 

t

θ

0

94

30

93

60

92

90

91

120

90

150

89

 

Table 3.2

Can

t / 

θ / 

0

93

30

91

60

90

90

89

120

88

150

87

 

The student repeats the procedure using a metal can, painted matt black, in place of the beaker.

The readings are shown in Table 3.2.

(i) Complete the column headings in Table 3.1 and in Table 3.2.

[1]

 

(ii) Look carefully at the readings in Table 3.1 and in Table 3.2.

Tick the box to show your conclusion from the readings.

square The water in the beaker has a greater rate of cooling than the water in the can.

square The water in the beaker has a smaller rate of cooling than the water in the can.

square There is no significant difference between the rates of cooling of the water in the beaker and the can.

[1]

(iii) Justify your conclusion by reference to the readings.

[2]

1c4 marks

A student in another school carries out the experiment and reports that the rate of cooling of the water in the can is different from the rate of cooling of the water in the beaker. He plans a change to the experiment to find out whether this difference in the rates of cooling is caused by 

  • the matt black surface of the can being a better radiator of thermal energy than the shiny surface of the beaker

  • the metal of the can being a better conductor of thermal energy than the material of the beaker.

(i) Suggest two suitable changes to the apparatus that the student could make.

[2]

(ii) Suggest two variables that should be controlled in order to make the experiment a fair test.

[2]

1d1 mark

State one precaution that you would take in order to record accurate temperature readings.

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27 marks

A student is investigating ways of slowing the rate of cooling of hot liquids in a container. The student knows that a lid will reduce the rate of cooling. He wants to find out if the thickness of the lid makes any difference to the rate of cooling.

  Plan an experiment which will enable him to compare the effects of lids of different thicknesses.

In your plan, you should:

  • list the apparatus needed

  • explain briefly how you would carry out the investigation, including the measurements to be taken

  • state any key variables that would need to be kept the same

  • draw a suitable table or tables, with column headings, to show how the readings would be displayed (you are not required to enter any readings in the table)

  • explain how you would use your readings to reach a conclusion.

You may draw a diagram if it helps to explain your plan.

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3a1 mark

Students are investigating the cooling of hot water in a beaker.

They are using the apparatus shown in Fig. 2.1.

q2-a

Record room temperature θR in °C shown on the thermometer in Fig. 2.1.

θR = ........................................................ 

3b2 marks

A volume of 150 cm3 of hot water is poured into the beaker and the initial temperature θ is recorded in Table 2.1.

The temperature of the water is recorded every 30 s. The values are shown in Table 2.1.

(i) Complete the headings in Table 2.1.

[1]

Table 2.1

t/

θ/

0

95.0

30

89.0

60

83.5

90

79.0

120

75.0

150

71.5

180

68.5

210

66.0

240

64.0

270

62.5

(ii) Describe one precaution that you would take to ensure that the temperature readings in the experiment are as accurate as possible.

[1]

3c3 marks

(i) Calculate the average cooling rate x1 during the first 90s of the experiment. Use the readings from Table 2.1 and the equation

x subscript 1 equals fraction numerator theta subscript 0 minus theta subscript 90 over denominator T end fraction 

where T = 90 s and θ0 and θ90 are the temperatures at t = 0 and t = 90 s.

Include the unit for the cooling rate.

 x1 = ........................................................ [1]

 

(ii) Calculate the average cooling rate x2 during the middle 90 s of the experiment. Use the readings from Table 2.1 and the equation

x subscript 2 equals fraction numerator theta subscript 90 minus theta subscript 180 over denominator T end fraction

 where T = 90 s and θ90 and θ180 are the temperatures at t = 90 and t = 180 s.

x2 = ........................................................ [1]

 

(iii) Calculate the average cooling rate x3 during the last 90 s of the experiment. Use the readings from Table 2.1 and the equation

x subscript 3 equals fraction numerator theta subscript 180 minus theta subscript 270 over denominator T end fraction

where T = 90 s and θ180 and θ270 are the temperatures at t = 180 and t = 270 s.

 x3 = ........................................................ [1]

3d2 marks

(i) The temperature of the water falls as time passes. Use the results from (c) to describe the pattern of the rate of cooling of the water during the experiment.

Justify your answer by reference to the results.

[1]

(ii) Give an estimate of the probable final temperature θF of the water if left to cool for many hours.

 

θF = ........................................................ [1]

3e3 marks

(i) A student in another school carries out a similar experiment.

She starts with the hot water at a lower initial temperature.

Suggest how her cooling rates are likely to compare with those calculated in (c).

Use the results to explain your answer.

[2]

 

(ii) State one variable, other than the initial temperature, which the student should control.

[1]

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4a1 mark

Students are investigating how the use of a lid or insulation affects the rate of cooling of hot water in a beaker. They use the apparatus shown in Fig. 2.1.

p3-2a

Record the room temperature θR in °C shown on the thermometer in Fig. 2.1.

 

θR = ........................................................ 

4b2 marks
  • 100 cm3 of hot water is poured into beaker A and the initial temperature θ is recorded in Table 2.1.

  • The temperature θ of the water at times t = 30 s, 60 s, 90 s, 120 s, 150 s and 180 s are shown in Table 2.1.

  • This process is repeated for beaker B.

Complete the headings and the time column in Table 2.1.

Table 2.1

beaker A with insulation

beaker B with a lid

t/

θ/

θ/

0

83.0

86.0

79.0

84.0

75.5

82.5

73.0

81.0

71.0

80.0

69.5

79.0

68.5

78.5

4c2 marks

Write a conclusion stating whether the insulation or the lid is more effective in reducing the cooling rate of the water in the beakers in this experiment.

 

Justify your answer by reference to the results.

4d2 marks

One student thinks that the experiment does not show how effective insulation is on its own or how effective a lid is on its own.

  Suggest an additional experiment which could be used to show how effective a lid or insulation is.

  Explain how the additional results could be used.

4e4 marks

(i) Calculate xA, the average cooling rate for beaker A over the whole experiment. Use the readings for beaker A from Table 2.1 and the equation

 x subscript straight A space equals space fraction numerator theta subscript 0 space minus space theta subscript 180 over denominator T end fraction

where T = 180 s and θ0 and θ180 are the temperatures at time t = 0 and time t = 180 s. Include the unit for the cooling rate.

 

 

xA = ........................................................ [2]

 

(ii) Students in another school are carrying out this experiment using identical equipment.

 State why they should make the initial temperature of the water the same as in this experiment if they are to obtain average cooling rates that are the same as in Table 2.1. Assume that the room temperature is the same in each case.

Use the results from beaker A to explain why this factor should be controlled.

[2]

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57 marks

A student investigates the effect of the colour of the surface of a metal container on the rate of loss of heat from the container. She knows that black surfaces are better radiators of thermal energy than white surfaces and wants to investigate the effect of other colours.

The following apparatus is available:

metal containers each with the outer surface painted a different colour

a thermometer

a stop-watch

a supply of hot water.

She can also use other apparatus and materials that are usually available in a school laboratory.

Plan an experiment to investigate the effect of the colour of the surface of a metal container on the rate of loss of heat from the container.

You should:

  • draw a diagram of the apparatus used

  • explain briefly how you would carry out the investigation

  • state the key variables to be kept constant

  • draw a table, or tables, with column headings, to show how you would display your readings (you are not required to enter any readings in the table)

  • explain how you would use your readings to reach a conclusion.

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6a3 marks

Some students are investigating how the volume of water affects the rate at which water in a beaker cools.

 

atp-3

They are using the apparatus shown in Fig. 2.1. 

(i) 200 cm3 of hot water is poured into beaker A and the initial temperature rises to the value shown on thermometer A in Fig. 2.1.

 In the first row of Table 2.1, record this temperature θA for time t = 0.

 100 cm3 of hot water is poured into beaker B. The temperature rises to the value shown on thermometer B in Fig. 2.1.

 In the first row of the table, record this temperature θB for time t = 0.

[1]

(ii) The temperatures θA and θB of the water in each experiment at times t = 30 s, 60 s, 90 s, 120 s, 150 s and 180 s are shown in the table.

Complete the headings and the time column in the table.

[2]

Table 2.1

 

beaker A with 200 cm3 of water

beaker B with 100 cm3 of water

t/

θA/

θB/

0

 

 

 

85.0

86.0

 

83.0

83.0

 

81.5

80.5

 

80.0

78.0

 

78.5

76.0

 

77.5

74.5

6b1 mark

Describe one precaution which should be taken to ensure that the temperature readings in the experiment are as accurate as possible.

6c2 marks

Write a conclusion stating how the volume of water in the beaker affects the rate of cooling of the water. Justify your answer by reference to the results.

6d2 marks

(i) Using the results for 100 cm3 of water, calculate the average rate of cooling x1 for the first 90 s of the experiment. Use the readings from the table and the equation

x subscript 1 space equals space fraction numerator theta subscript 0 space – space theta subscript 90 over denominator t end fraction

 where t = 90 s and θ0 and θ90 are the temperatures at time 0 and at time 90 s. Include the unit for the rate of cooling.

 

x1 = ...........................................................[1]

(ii) Using the results for 100 cm3 of water, calculate the average rate of cooling x2 in the last 90 s of the experiment. Use the readings from the table and the equation

 x subscript 2 space equals space fraction numerator theta subscript 90 space – space theta subscript 180 over denominator t end fraction

where t = 90 s and θ90 and θ180 are the temperatures at time 90 s and at time 180 s. Include the unit for the rate of cooling.

 

 

x2 = ............................................................[1]

6e1 mark

A student suggests that it is important that the experiments with the two volumes of water should have the same starting temperatures.

 State whether your values for x1 and x2 support this suggestion. Justify your statement with reference to your results.

6f2 marks

Another student plans to investigate whether more thermal energy is lost from the water surface than from the sides of the beakers.

 Describe an experiment that could be done to investigate this.

 You may draw a diagram to help your description.

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