Ch11 Energy and Thermo - University Of...
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Forms of Energy Mechanical Energy U g U s K Thermal Energy E th Other forms include E chem E nuclear Slide 10-10
Transcript of Ch11 Energy and Thermo - University Of...
Forms of EnergyMechanical Energy
Ug UsK
ThermalEnergy
Eth
Other forms include
Echem
Enuclear
Slide 10-10
Forces of Nature - Gravitational
Efficiency
Slide 11-8
Reading Quiz1. A machine uses 1000 J of electric energy to raise a heavy
mass, increasing its potential energy by 300 J. What is theefficiency of this process?
A. 100%B. 85%C. 70%D. 35%E. 30%
Slide 11-6
Example ProblemLight bulbs are rated by the power that they consume, not thelight that they emit. A 100 W incandescent bulb emitsapproximately 4 W of visible light. What is the efficiency of thebulb?
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Forces of Nature - Electromagnetic
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Helium Nucleus
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Forces of Nature - Nuclear
Short range
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Forces of Nature - Nuclear
Uranium~ 238
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Nuclear Quakes
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Energy from nuclear physics
fission
fusion
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Fusion Fire Powers the Sun
Stars – Fusion Reactors"Every time you lookup at the sky, everyone of those pointsof light is a reminderthat fusion power isextractable fromhydrogen ….,and it is an everydayreality throughoutthe Milky WayGalaxy."
--- Carl Sagan,Spitzer Lecture,October 1991
Forces of Nature - Electromagnetic
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Chemical Compactification
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Energy UnitsEnergy Units
•• Joule = Joule = 1 kg m1 kg m22/s/s22
•• calorie = calorie = energy to raise temperature of 1 g of water by oneenergy to raise temperature of 1 g of water by onedegree Cdegree C
•• 1 calorie = 4.186 J 1 calorie = 4.186 J
•• CCalorie (food) = 1 kcal = 1,000 alorie (food) = 1 kcal = 1,000 ccaloriesalories
•• 1 Calorie = 100W light bulb on for about 7 minutes1 Calorie = 100W light bulb on for about 7 minutes
Efficiency
What you get:Change in potentialenergy, 1800 J
What you had to pay:Energy used by thebody, 7200 J
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End
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