Transfer of Thermal Energy

Physics, SSC-Punjab Class 10. This chapter is split into 34 topics and has 785 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Numericals: heat leak through insulation 24 questions
2. Greenhouse effect and temperature regulation in a greenhouse 22 questions
3. Heat transfer and thermal equilibrium 23 questions
4. Radiation: heat transfer without a medium 24 questions
5. Effect of surface colour and texture on infrared radiation 24 questions
6. Infrared thermometer 22 questions
7. Thermal insulation: the thermos flask 23 questions
8. Exercise-style reasoning: radiation, convection and equilibrium 21 questions
9. Numericals: hot water drawn from a tank and mixing 24 questions
10. Comparing absorption of radiation by different surfaces 23 questions
11. Surface temperature and surface area in radiation 21 questions
12. Why objects cool or warm over time 24 questions
13. Comparing conduction, convection and radiation 25 questions
14. Convection currents in air and their applications 22 questions
15. Thermal conduction in metals, free electrons and conductors 22 questions
16. Convection experiment with potassium permanganate 22 questions
17. Gliders, birds and thermals 23 questions
18. Numericals: electric storage tank water heater 24 questions
19. Identifying the mode of heat transfer in everyday situations 26 questions
20. Heating objects: kitchen pans 22 questions
21. Leslie's cube: emission and absorption of radiation 25 questions
22. Convection in liquids and gases 23 questions
23. Land breeze and sea breeze 23 questions
24. Numericals: warming the air of a room 24 questions
25. Heating rooms and household hot-water systems 23 questions
26. Reducing thermal energy transfer in buildings 23 questions
27. Numericals: radiant energy melting ice and heating water 24 questions
28. Greenhouse effect on Earth and global warming 22 questions
29. Radiation from a fireplace 22 questions
30. Convection in seawater and marine life 22 questions
31. Numericals: energy received from the Sun by radiation 24 questions
32. Numericals: cooling of a hot drink and the thermos flask 24 questions
33. Conduction: heat transfer by direct contact 21 questions
34. Exercise-style multiple choice: transfer of thermal energy 24 questions

Sample questions: Transfer of Thermal Energy

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. A student says heat 'rises'. Which statement best describes what really happens?

• A. Heat can only move upward in solids
• B. Heat is a substance that always moves upward
• C. Cold is a substance that always moves downward
• D. Hot fluids rise(correct answer)

Answer: D.Hot fluids become less dense and rise in convection, but heat transfer in general depends only on the temperature difference.

Q2. Conduction is the transfer of heat through

• A. the evaporation of a liquid surface
• B. direct contact between particles in a material(correct answer)
• C. the movement of fluids in a closed loop
• D. electromagnetic waves across empty space

Answer: B.Conduction passes thermal energy from particle to particle without any movement of the material as a whole.

Q3. 10 kg of hot water at 60 °C from a tank is mixed with 30 kg of cold water at 20 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 20 °C
• B. 15 °C
• C. 40 °C
• D. 30 °C(correct answer)

Answer: D.Heat lost by hot water = heat gained by cold water: 10(60 − T) = 30(T − 20). So T = (10 × 60 + 30 × 20) / 40 = 30 °C.

Q4. 5 kg of hot water at 55 °C from a tank is mixed with 10 kg of cold water at 25 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 35 °C(correct answer)
• B. 40 °C
• C. 45 °C
• D. 18.33 °C

Answer: A.Heat lost by hot water = heat gained by cold water: 5(55 − T) = 10(T − 25). So T = (5 × 55 + 10 × 25) / 15 = 35 °C.

Q5. 20 kg of hot water at 60 °C from a tank is mixed with 40 kg of cold water at 15 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 30 °C(correct answer)
• B. 37.5 °C
• C. 40 °C
• D. 20 °C

Answer: A.Heat lost by hot water = heat gained by cold water: 20(60 − T) = 40(T − 15). So T = (20 × 60 + 40 × 15) / 60 = 30 °C.

Q6. 14 kg of hot water at 55 °C from a tank is mixed with 28 kg of cold water at 20 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 31.67 °C(correct answer)
• B. 21.67 °C
• C. 41.67 °C
• D. 18.33 °C

Answer: A.Heat lost by hot water = heat gained by cold water: 14(55 − T) = 28(T − 20). So T = (14 × 55 + 28 × 20) / 42 = 31.67 °C.

Q7. 16 kg of hot water at 70 °C from a tank is mixed with 32 kg of cold water at 20 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 46.67 °C
• B. 36.67 °C(correct answer)
• C. 26.67 °C
• D. 45 °C

Answer: B.Heat lost by hot water = heat gained by cold water: 16(70 − T) = 32(T − 20). So T = (16 × 70 + 32 × 20) / 48 = 36.67 °C.

Q8. 13 kg of hot water at 75 °C from a tank is mixed with 26 kg of cold water at 25 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 41.67 °C(correct answer)
• B. 51.67 °C
• C. 25 °C
• D. 50 °C

Answer: A.Heat lost by hot water = heat gained by cold water: 13(75 − T) = 26(T − 25). So T = (13 × 75 + 26 × 25) / 39 = 41.67 °C.

Q9. 10 kg of hot water at 58 °C from a tank is mixed with 25 kg of cold water at 18 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 29.43 °C(correct answer)
• B. 19.43 °C
• C. 16.57 °C
• D. 38 °C

Answer: A.Heat lost by hot water = heat gained by cold water: 10(58 − T) = 25(T − 18). So T = (10 × 58 + 25 × 18) / 35 = 29.43 °C.

Q10. 9 kg of hot water at 64 °C from a tank is mixed with 18 kg of cold water at 14 °C in a bucket. Ignoring heat losses, what is the final temperature of the mixture?

• A. 40.67 °C
• B. 20.67 °C
• C. 21.33 °C
• D. 30.67 °C(correct answer)

Answer: D.Heat lost by hot water = heat gained by cold water: 9(64 − T) = 18(T − 14). So T = (9 × 64 + 18 × 14) / 27 = 30.67 °C.