Thermodynamics and engines: AQA A‑Level Physics questions

Every AQA A-Level Physics exam question on 3.11.2 Thermodynamics and engines, 2016–2025, with its mark scheme and examiner’s report.

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Q03.1
June 2025 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q03.2
June 2025 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q03.3
June 2025 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q03.4
June 2025 · Paper 3 Engineering physics
3 marks3.11.2 Thermodynamics and engines
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Q03.5
June 2025 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q03.6
June 2025 · Paper 3 Engineering physics
6 marks3.11.2 Thermodynamics and engines
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Q04.1
June 2025 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q04.2
June 2025 · Paper 3 Engineering physics
3 marks3.11.2 Thermodynamics and engines
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Q04.3
June 2025 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q03.1
June 2024 · Paper 3 Engineering physics
5 marks3.11.2 Thermodynamics and engines
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Q03.2
June 2024 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q03.3
June 2024 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q03.4
June 2024 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q04.1
June 2024 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q04.2
June 2024 · Paper 3 Engineering physics
3 marks3.11.2 Thermodynamics and engines
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Q04.3
June 2024 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q04.4
June 2024 · Paper 3 Engineering physics
2 marks3.11.2 Thermodynamics and engines
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Q03.1
June 2023 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q03.2
June 2023 · Paper 3 Engineering physics
1 mark3.11.2 Thermodynamics and engines
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Q03.3
June 2023 · Paper 3 Engineering physics
3 marks3.11.2 Thermodynamics and engines
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All 71 questions on Thermodynamics and engines, as a list

June 2025, Paper 3 Engineering physics, Q03.1 (1 mark): State what is meant by an isothermal change. [1 mark] Figure 6 shows a p–V diagram in which a fixed mass of an ideal gas is taken through a cycle of three proce
June 2025, Paper 3 Engineering physics, Q03.2 (2 marks): Calculate, in mol, the amount of gas. [2 marks] amount of gas = mol
June 2025, Paper 3 Engineering physics, Q03.3 (1 mark): Show that the work done in process C → A is about 100 J. [1 mark]
June 2025, Paper 3 Engineering physics, Q03.4 (3 marks): Complete Table 2 for each process and for the whole cycle. [3 marks] Table 2 Q / J W / J ΔU / J Process A → B −253 Process B → C 473 Process C → A −253 Whole cy
June 2025, Paper 3 Engineering physics, Q03.5 (2 marks): Two criteria for a heat engine to achieve the maximum theoretical efficiency are: 1. the gas must always be at the same temperature as the hot source when energ
June 2025, Paper 3 Engineering physics, Q03.6 (6 marks): The overall efficiency of a heat engine is defined as overall efficiency = net work output in one cycle energy supplied by heat transfer in one cycle An enginee
June 2025, Paper 3 Engineering physics, Q04.1 (1 mark): State what is meant by the coefficient of performance of a heat pump. [1 mark] A jeweller hopes to reduce workshop heating costs by replacing a gas-fired boiler
June 2025, Paper 3 Engineering physics, Q04.2 (3 marks): Comment on the salesperson’s claims. [3 marks]
June 2025, Paper 3 Engineering physics, Q04.3 (1 mark): A heat pump is installed. The average COPhp over the winter period is 7.5 In this period the heat pump delivers 2880 kW h of underfloor heating. What is the ele
June 2024, Paper 3 Engineering physics, Q03.1 (5 marks): The indicator diagram is for a rotational speed of the crankshaft of 120 rev min−1. Determine, using Figure 7, the indicated power of the engine. Assume that th
June 2024, Paper 3 Engineering physics, Q03.2 (2 marks): The following data are taken during the test on the engine: fuel consumption = 6.44 × 10−4 m3 s−1 calorific value of fuel = 18.0 × 106 J m−3 torque at crankshaf
June 2024, Paper 3 Engineering physics, Q03.3 (2 marks): The output power of a four-stroke petrol engine of a similar working volume to that of the Lenoir engine is about 150 kW. Suggest two reasons for the very low o
June 2024, Paper 3 Engineering physics, Q03.4 (1 mark): Which statement is correct? Tick () one box. [1 mark]
June 2024, Paper 3 Engineering physics, Q04.1 (2 marks): The first law of thermodynamics can be expressed by the equation Q = ΔU + W. State the meaning of each term in this equation. [2 marks] Q ΔU W
June 2024, Paper 3 Engineering physics, Q04.2 (3 marks): A system consists of a perfectly insulated room containing only an empty refrigerator. The refrigerator is connected to the mains electricity and the refrigerat
June 2024, Paper 3 Engineering physics, Q04.3 (1 mark): Complete Figure 8 so that the engine obeys the second law of thermodynamics. [1 mark]
June 2024, Paper 3 Engineering physics, Q04.4 (2 marks): Explain why the maximum theoretical efficiency of an ideal heat engine must be less than 100%. [2 marks]
June 2023, Paper 3 Engineering physics, Q03.1 (1 mark): The first law of thermodynamics can be written as: Q = ΔU + W State what Q represents in this equation. [1 mark]
June 2023, Paper 3 Engineering physics, Q03.2 (1 mark): The work done on the air when it is compressed is 10.8 mJ. Which row is correct for this adiabatic compression? Tick () one box. [1 mark] W / mJ Q / mJ ΔU / mJ
June 2023, Paper 3 Engineering physics, Q03.3 (3 marks): The initial conditions for the air are: volume of air = 2.91 × 10−8 m3 pressure of air = 1.05 × 105 Pa temperature of air = 293 K. During sudden braking, the ai
June 2023, Paper 3 Engineering physics, Q03.4 (2 marks): To produce the adiabatic change, the brake lever is pulled very quickly. The cyclist thinks that by applying the brake slowly, the work done to compress the bub
June 2023, Paper 3 Engineering physics, Q04 (6 marks): Figure 7 shows the p–V diagram for a theoretical diesel engine cycle. Figure 8 shows the indicator diagram for a real four-stroke diesel engine working between
June 2023, Paper 3 Engineering physics, Q05.1 (1 mark): Calculate the efficiency of this engine. [1 mark] efficiency =
June 2023, Paper 3 Engineering physics, Q05.2 (3 marks): Figure 10 shows another system operating between the same overall temperatures and with the same input power as the engine in Figure 9. This system consists of
June 2022, Paper 3 Engineering physics, Q03.1 (1 mark): Explain what is meant by an adiabatic change. [1 mark]
June 2022, Paper 3 Engineering physics, Q03.2 (2 marks): Figure 4 shows the p–V diagram for an ideal diesel engine cycle. Figure 4 In this cycle, air is compressed adiabatically from a pressure of 1.0 × 105 Pa and vol
June 2022, Paper 3 Engineering physics, Q03.3 (2 marks): Explain why the compression ratio for a diesel engine must be greater than the compression ratio for a petrol engine. [2 marks]
June 2022, Paper 3 Engineering physics, Q03.4 (2 marks): Draw, on Figure 5, a typical indicator diagram for a real four-stroke diesel engine with the same values of V1 and V2. [2 marks] Figure 5
June 2022, Paper 3 Engineering physics, Q03.5 (1 mark): Mark with an X on your diagram the point where the injection of fuel starts. [1 mark]
June 2022, Paper 3 Engineering physics, Q03.6 (2 marks): Explain two differences between the ideal cycle and the indicator diagram for the real engine. [2 marks] 1 2
June 2022, Paper 3 Engineering physics, Q04.1 (4 marks): It is claimed that the coefficient of performance (COP) of a thermoelectric refrigerator is much less than the COP of an ideal refrigerator. Discuss whether the
June 2022, Paper 3 Engineering physics, Q04.2 (2 marks): Suggest why a small value of the COP might be acceptable for this particular application of a thermoelectric cooling element. [2 marks]
November 2021, Paper 3 Engineering physics, Q03.1 (6 marks): Figure 4 can be used to analyse the performance of the engine. Determine, for the speed at which the engine develops its maximum brake power: • the overall effi
November 2021, Paper 3 Engineering physics, Q03.2 (2 marks): Explain why it is not advisable to run this engine at speeds above 7000 rev min−1. Refer to Figure 4 in your answer. [2 marks]
November 2021, Paper 3 Engineering physics, Q04.1 (5 marks): Figure 6 shows the variation of pressure p with volume V as the gas expands on the right-hand side of the piston when the correct nail is used. Figure 6 The com
November 2021, Paper 3 Engineering physics, Q04.2 (3 marks): After a nail has been used, another nail takes its place automatically. The tool can drive up to 180 nails per minute. Discuss why the expansion cannot be isoth
November 2021, Paper 3 Engineering physics, Q05.1 (1 mark): Which is a correct statement about an ideal heat engine? Tick () one box. [1 mark]
November 2021, Paper 3 Engineering physics, Q05.2 (2 marks): An ideal heat engine has an efficiency of 0.33 The same engine works in reverse as an ideal refrigerator between the same hot and cold spaces. Determine the coe
November 2020, Paper 3 Engineering physics, Q03 (6 marks): Figure 4 shows some of the equipment used to investigate the thermal and mechanical efficiencies of a single-cylinder four-stroke petrol engine. Figure 4 • Petr
November 2020, Paper 3 Engineering physics, Q04.1 (1 mark): Which row in Table 3 shows • Process 1 in which work done is zero, and • Process 2 in which the change in internal energy is zero? Tick () one box. [1 mark] Ta
November 2020, Paper 3 Engineering physics, Q04.2 (3 marks): When irregular particles are packed, air gaps are left between the particles. The true volume of a quantity of irregular particles must be determined using a me
November 2020, Paper 3 Engineering physics, Q04.3 (2 marks): Sketch on Figure 6 the variation of pressure with volume when the plunger is pushed in fully very quickly and then left for several seconds. Assume no leakage p
November 2020, Paper 3 Engineering physics, Q04.4 (2 marks): Explain why the compression of a gas can be considered to be an isothermal change when the gas is compressed very slowly. [2 marks]
November 2020, Paper 3 Engineering physics, Q05.1 (2 marks): Explain how the second law of thermodynamics predicts that a heat engine can never be 100% efficient. [2 marks]
November 2020, Paper 3 Engineering physics, Q05.2 (4 marks): A company plans to build a geothermal power station in a region where there is hot rock deep below the surface. The scheme is shown in Figure 7. Figure 7 In the
June 2019, Paper 3 Engineering physics, Q03.1 (1 mark): Show, by calculation, that the volume at B is 4.1 × 10−2 m3. [1 mark]
June 2019, Paper 3 Engineering physics, Q03.2 (2 marks): The temperature of the air between A and B is 295 K. Show that the temperature of the air at C is about 420 K. [2 marks]
June 2019, Paper 3 Engineering physics, Q03.3 (2 marks): An ideal engine based on this cycle uses a device called an economiser. The economiser stores all the energy transferred in the cooling process D → A and gives
June 2019, Paper 3 Engineering physics, Q03.4 (2 marks): Explain why W is equal to Q in process A → B and in process C → D. [2 marks]
June 2019, Paper 3 Engineering physics, Q03.5 (3 marks): It is claimed that the efficiency of this engine cycle is the same as the maximum theoretical efficiency of a heat engine operating between the same temperature
June 2019, Paper 3 Engineering physics, Q03.6 (2 marks): Discuss one problem that would be faced by an engineer designing a real engine based on this cycle. [2 marks]
June 2019, Paper 3 Engineering physics, Q04.1 (2 marks): A typical conventional tumble-dryer uses about 0.6 kW h per kg of clothes. A heat pump tumble-dryer uses about 0.25 kW h per kg. Explain why the heat pump tumbl
June 2019, Paper 3 Engineering physics, Q04.2 (3 marks): The cold space of the heat pump is the room in which the tumble-dryer is placed. The hot space is the air in the tumble-dryer and is at a temperature of 160 °C.
June 2018, Paper 3 Engineering physics, Q03.1 (1 mark): Which statement about this cycle is true? Tick () the correct answer. [1 mark]
June 2018, Paper 3 Engineering physics, Q03.2 (5 marks): The cycle in Figure 3 may be modified by allowing the air to continue to expand adiabatically from state 4 until it is at atmospheric pressure at state 5. Figur
June 2018, Paper 3 Engineering physics, Q03.3 (2 marks): The first law of thermodynamics can be written as Q = ΔU + W State the meaning of the terms Q and ΔU in this equation. [2 marks] Q ΔU
June 2018, Paper 3 Engineering physics, Q03.4 (2 marks): For the air in process 5 → 1 in Figure 4, ΔU = –374 J Calculate the energy that must be removed by cooling for process 5 → 1. [2 marks] energy removed by coolin
June 2018, Paper 3 Engineering physics, Q03.5 (3 marks): 0.060 mol of air is taken through the cycle. Determine the maximum temperature in the cycle. [3 marks] maximum temperature = K
June 2018, Paper 3 Engineering physics, Q04 (6 marks): The National Grid is supplied mainly from power stations which have overall efficiencies of up to about 40% Table 1 shows the average power requirements of a la
June 2017, Paper 3 Engineering physics, Q03.1 (4 marks): The gas is initially at a pressure of 1.2 × 106 Pa, a volume of 9.0 × 10–5 m3 and a temperature of 290 K. When the lid is closed quickly the gas is compressed r
June 2017, Paper 3 Engineering physics, Q03.2 (2 marks): Explain why the rapid compression of the gas can be assumed to be an adiabatic process. [2 marks]
June 2017, Paper 3 Engineering physics, Q03.3 (3 marks): When the lid is closed slowly, the compression can be assumed to be isothermal. The gas can be compressed either isothermally or adiabatically from the same ini
June 2017, Paper 3 Engineering physics, Q04 (6 marks): Figure 5 shows the p—V diagram for a theoretical petrol engine cycle compared to the indicator diagram for a real four-stroke petrol engine with the same maximu
June 2017, Paper 3 Engineering physics, Q05.1 (1 mark): An ideal heat pump and an ideal refrigerator operate between the same hot and cold spaces. Which statement relating to the coefficient of performance (COP) is c
June 2017, Paper 3 Engineering physics, Q05.2 (3 marks): An ideal refrigerator operates between a cold space at a temperature of ̶ 1 °C and a hot space at a temperature of 70 °C. Calculate the input power to the refri
Specimen, Paper 3 Engineering physics, Q03.1 (3 marks): A single-cylinder air motor running on compressed air has the theoretical indicator diagram shown in Figure 4. • From B to C the high-pressure air pushes a pist
Specimen, Paper 3 Engineering physics, Q03.2 (6 marks): A single-cylinder air motor running on compressed air has the theoretical indicator diagram shown in Figure 4. • From B to C the high-pressure air pushes a pist
Specimen, Paper 3 Engineering physics, Q03.3 (4 marks): A single-cylinder air motor running on compressed air has the theoretical indicator diagram shown in Figure 4. • From B to C the high-pressure air pushes a pist
Specimen, Paper 3 Engineering physics, Q03.4 (1 mark): A single-cylinder air motor running on compressed air has the theoretical indicator diagram shown in Figure 4. • From B to C the high-pressure air pushes a pist
Specimen, Paper 3 Engineering physics, Q04.1: A company claims to be able to provide a combined heat and power plant for a mark garden that requires both electrical power and space heating for greenhouses.
Specimen, Paper 3 Engineering physics, Q04.2 (5 marks): A company claims to be able to provide a combined heat and power plant for a mark garden that requires both electrical power and space heating for greenhouses.

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