Ch11 Energy and Thermo - University Of Marylandterpconnect.umd.edu/~hassam/121/notes/Powerpoints/Ch11 Energy … · Ch11 Energy and Thermo.ppt Author: adil hassam Created Date: 4/15/2012

Forms of EnergyMechanical Energy

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ThermalEnergy

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Other forms include

Echem

Enuclear

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Forces of Nature - Gravitational

Efficiency

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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%

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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

Quakescompactify

Energy from nuclear physics

fission

fusion

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

cloud

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PE

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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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