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# lecture_2 - Physics 140 Lecture 2 Blackbody Radiation Jan....

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Physics 140 Lecture 2 Blackbody Radiation Jan. 23, 2012 1 Sunday, January 29, 12

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Announcements 2 1) By midnight tonight the frst homework assignment will be posted on the course web site: http://physics.rutgers.edu/ugrad/140/ 2) The lectures notes are now on the course web site. 3) By now you should have read: Dire Predictions -- pp. 14-15, 22-31 Beyond Smoke and Mirrors -- pp. 1-15 Sunday, January 29, 12
Forms of Energy 3 Kinetic energy (energy of motion) Gravitational energy Electrical energy Chemical energy Light energy Spring (elastic) energy Nuclear energy Mass energy ( E = mc 2 ) Thermal energy Sunday, January 29, 12

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Amounts of Energy 4 1 Calorie = 4000 Joules bullet 40 J 0.01 Cal 1 pound of TNT 1,000,000 J 250 Cal 1 pound of chocolate chip cookies 8,000,000 J 2000 Cal person running at 10 miles per hour 600 J 0.15 Cal car traveling at 60 miles per hour 600,000 J 150 Cal energy used in US in one year 10 20 J 2 x 10 16 Cal Sunday, January 29, 12
Conservation of Energy 5 Energy is conserved The total amount of energy in the universe remains constant Why do we have to worry about energy then? One of the most fundamental laws in physics Energy may change from one form to another but if we add up all of the forms of energy the total is constant Sunday, January 29, 12

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Thermal Energy 6 Thermal energy is the kinetic energy of molecules. It is hidden because you can’t see molecules. They are too small. Friction changes macroscopic kinetic energy into thermal energy. Thermal energy is not useful energy Everything that we do increases thermal (non useful) energy Sunday, January 29, 12
Power 7 Power is the rate at which energy is used or produced Power = Energy / Time Power is measured in Watts (W) 1 Watt = 1 Joule per second Horsepower (hp) is another measure of power 1 hp = 1 kW 1 hp is the power expended in raising 330 pounds by 100 feet in one minute What is a kiloWatt hour (kWh)? 3.6 MJ Sunday, January 29, 12

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Power Consumption 8 What is the average power consumption of the US?
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## This note was uploaded on 02/06/2012 for the course PHYSICS 140 taught by Professor Staff during the Spring '08 term at Rutgers.

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lecture_2 - Physics 140 Lecture 2 Blackbody Radiation Jan....

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