N1 Engineering Science|The Easy Way! 81 Exercise 4.2 1. Mention three ways in which heat transfer can take place.


2. Give one example of each method of heat transfer mentioned in question 1 above. 3. Describe, with the aid of a sketch, an experiment to prove heat propagation by conduction.


4. Describe with the aid of a neat, labelled sketch, an experiment to illustrate convection.


5. Can heat be reflected? Give an example. 6. Make a neat, labelled sketch of an apparatus which is designed to radiate heat energy.


7. Mention four effects that can take place when heat is added to a substance. 8. Does the temperature of a substance always rise when heat is added to it? 9. Give two examples where the addition of heat does not cause a rise in temperature.


10. What will happen if two lengths of wiremade of copper and steel are joined together at their ends, with their ends maintained at different temperatures.


11. What kind of instrument operates on the principle of question 10 above. 12. Make a diagrammatical sketch of a thermocouple. 13. Give two practical examples of where thermocouples can be used.


Exercise 4.3


1. Consider two gas burners with equal flames. One kg of copper is placed on the one and 1 kg of water on the other. Tey were both at the same temperature when placed on the flames for the same amount of time, e.g. 2 minutes. Assume that no heat is lost during the process. 1.1 Which one will have the highest temperature after 2 minutes? 1.2 Which one will have absorbed themost heat energy? 1.3 Why is there a difference in temperature between the two?


2. Explain what is meant by specific heat capacity.


3. What does the symbol 3t represent, and how can it be calculated? 4. In what unit is specific heat capacitymeasured?


5. Write down the equation used to determine specific heat capacity. Give the unit of each symbol.


6. If the specific heat capacity of water is given as 4,2 kJ/kg °C and it is to be used in a calculation, what is important to bear in mind?


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