Transcript Ch 11
Chapter 11
Using Energy
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PowerPoint ® Lectures for College Physics: A Strategic Approach, Second Edition
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Efficiency © 2010 Pearson Education, Inc.
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Reading Quiz 1. A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process?
A.
B.
C.
D.
E.
100% 85% 70% 35% 30% © 2010 Pearson Education, Inc.
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Answer 1. A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process?
A.
B.
C.
D.
E.
100% 85% 70% 35%
30%
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Example Problem Light bulbs are rated by the power that they consume, not the light that they emit. A 100 W incandescent bulb emits approximately 4 W of visible light. What is the efficiency of the bulb?
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The Ideal Gas Model
T
2 3
K
avg
k
B © 2010 Pearson Education, Inc.
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Checking Understanding:Temperature Scales Rank the following temperatures, from highest to lowest.
A.
B.
C.
D.
300 °C > 300 K > 300 °F 300 K > 300 °C > 300 °F 300 °F > 300 °C > 300 K 300 °C > 300 °F > 300 K © 2010 Pearson Education, Inc.
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Answer Rank the following temperatures, from highest to lowest.
A.
B.
C.
D.
300 °C > 300 K > 300 °F 300 K > 300 °C > 300 °F 300 °F > 300 °C > 300 K
300 °C > 300 °F > 300 K
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What is Heat??
Energy transferred between 2 objects at different temperatures.
Always flows from hot to cold Zeroth Law of Thermodynamics: © 2010 Pearson Education, Inc.
How to increase the thermal (internal) energy of the water?
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D U = W + Q Slide 11-23
First Law of Thermodynamics D U = Q + W +Q…heat flows into system -Q…heat flows out of system +W…Work done ON System -W…Work done BY system © 2010 Pearson Education, Inc.
Operation of a Heat Engine © 2010 Pearson Education, Inc.
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The Theoretical Maximum Efficiency of a Heat Engine © 2010 Pearson Education, Inc.
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Operation of a Heat Pump © 2010 Pearson Education, Inc.
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Second Law of Thermodynamics © 2010 Pearson Education, Inc.
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Summary © 2010 Pearson Education, Inc.
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Summary © 2010 Pearson Education, Inc.
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