Physics 1215 Reading Questions
Assignment #3

Chapter 15.0 - 15.12

Reading Questions should be submitted electronically using this form. They are due by 8:00 a.m. on Wednesday, January 30, 2008.
Any Reading Questions arriving late will receive no credit.
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Answer the Reading Questions below. Please answer each question.

1. State in your own words, what the second law of thermodynamics says.

2. Is it possible to build a real Carnot engine? Why or why not?

3. You are running an engine with an input temperature of 1000 K and an output temperature of 500 K. What is the maximum efficiency this engine could possibly have?

4. Suppose your refrigerator is not working too well and you want to do something to make it more efficient. Assuming you have an ideal refrigerator operating like a Carnot heat pump, is it better to move it to a room that is five degrees cooler, to raise the temperature inside the refrigerator by five degrees, or does either have the same effect? Explain.

5. Define entropy.

6. Does entropy have to be calculated using the equation dS = dQ/T? Why or why not?

7. Water is heated on a stove. Rank the entropy change of the water, from least to greatest, as its temperature rises from (a) 20-30 C, (b) 30-35 C, (c) 80-85 C.

(a), (b), (c)
(a), (c), (b)
(b), (a), (c)
(b), (c), (a)
(c), (a), (b)
(c), (b), (a)

8. How would you make an engine that is 100% efficient? Is this possible? Why or why not?

9. How does the change in entropy relate to a direction for time?

10. How does entropy relate to probability?

Final Question: (This question must be answered to receive any credit). What is one thing from the chapter that you didn't understand or need clarified?

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