PHY2048 - GENERAL PHYSICS I
REVISION QUESTIONS FOR CHAPTER 20

Below you will find a set of 5 conceptual and numerical revision questions selected randomly from lots of questions I have put together covering the material in Chapter 20, "The Second Law of Thermodynamics". This includes questions on the Second Law, heat engines, refrigerators and heat pumps. When you have finished the quiz, click on the "Submit Quiz" button at the bottom and within seconds it will be automatically graded and the results returned to you!

To select a new set of questions click on the "Reload" or "Refresh" button on your browser. You may find some of the questions duplicated but that's the nature of a random selection. Try it a few times ... it's not fattening and you may learn something!

Many thanks to Mark Wood for producing the quiz-maker code.


Q1: A heat engine absorbs 70 kcal of heat from a hot reservoir and exhausts 50 kcal to a cold reservoir each cycle. What is its efficiency?

20%
24%
29%
33%
37%

Q2: A container holding 1.2 kg of water at 20°C is placed in a freezer which is kept at -20°C. The water freezes and comes into thermal equilibrium with the interior of the freezer. How much heat is extracted from the water in this process?

48 kJ
100 kJ
400 kJ
549 kJ
348 kJ

Q3: The efficiency of a Carnot engine operating between 300°C and 250°C is about

83%
17%
57%
43%
9%

Q4: You can alter the efficiency of a Carnot engine by varying the temperature of the cold reservoir while maintaining the hot reservoir at constant temperature.

Which one of the curves above best represents the efficiency of such an engine as a function of the temperature of the cold reservoir?

1
2
3
4
5


Q5: What is the maximum possible coefficient of performance of a heat pump that is capable of maintaining the interior of a house at +20°C when the temperature outside is -40°C?

2.0
5.2
12
4.9
3.9

Click on the Submit Quiz button below to have your quiz automatically graded.

Please note that you may be able to use the "Back" and "Forward" buttons on your browser to check the answers with the questions.