Lesson 6



Name:ETP Section:t3 Start Time:17:8:17 Instructor:pattersonet Course:421




1. Why don't we ordinarily see heat flow from cooler systems to hotter systems? (Consider this question on a couple of different levels -- e.g., ordinary words and mathematical expressions.) How can this notion of unidirectional heat flow be reconciled with the fact that the physics equations of motion are reversible in time?

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2. Suppose we have 20 moles of gas in a hot container (like our classroom!) and 20 moles of gas in a cool container. We extract 1200 J of energy from the hot gas and put that energy into the cooler gas. Estimate the approximate change in the total conventional entropy S because of this energy transfer. To what change in the (fundamental) entropy s does this correspond?

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3. As oscillating pengulum eventually comes to rest because of friction at the pivot point and collisions with air molecules. Its original mechanical energy is converted to thermal energy. The reverse of this scenario never occurs. Which of the laws of thermodynamics explains/describes this?

Check the correct answer:
a) Zeroth Law
b) First Law
c) Second Law
d) Third Law

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