Judah Levine, 3070L3 1http://physics.colorado.edu/phys3070http://physics.colorado.edu/phys3070Judah LevineJudah LevineJILA SJILA [email protected]@colorado.edu303 492303 492--7785 (27785 (2--7785)7785)M,F 11M,F 11--Noon, W 1Noon, W 1--3 pm3 pmalso by appointmentalso by appointmentJudah Levine, 3070L3 2The story of Baby Doe, Horace Tabor,and the Matchless mine in LeadvilleJudah Levine, 3070L3 3Homework for next weekHomework for next weekQQProject Project RulisonRulison––What was its purpose?What was its purpose?––Did it succeed?Did it succeed?QQEE--mail by next Monday, 10 ammail by next Monday, 10 am––1 paragraph min, 1 page max working 1 paragraph min, 1 page max working alonealone––1 page min, 2 pages max working with a 1 page min, 2 pages max working with a partnerpartnerJudah Levine, 3070L3 4Types of Energy Types of Energy ----11QQKinetic Energy Kinetic Energy ––the the energy of motionenergy of motionjoulesmvKE 905.180212122=××==m in kilograms, v in m/senergy in joulescannot use m in poundsJudah Levine, 3070L3 5Temperature and energyTemperature and energyQQMacroscopic vs. microscopic Macroscopic vs. microscopic parametersparametersQQTemperature as measure of kinetic Temperature as measure of kinetic energyenergy––TT∼∼KEKEQQ““AbsoluteAbsolute””temperature scaletemperature scale––T(Kelvin)= C + 273T(Kelvin)= C + 273––Not too coldNot too cold••Assume Assume ““ideal gasideal gas””behaviorbehaviorJudah Levine, 3070L3 6Clicker QuestionClicker QuestionQQThe speed of a molecule of air is about The speed of a molecule of air is about 300 300 m/sm/sat room temperature (300 K). at room temperature (300 K). The speed at 1200 K would be aboutThe speed at 1200 K would be aboutA: 600 A: 600 m/sm/sB: 1200 B: 1200 m/sm/sC: 150 C: 150 m/sm/sD: 75 D: 75 m/sm/sE: None of these valuesE: None of these valuesJudah Levine, 3070L3 7Clicker QuestionClicker QuestionQQThe speed of a molecule of air is about The speed of a molecule of air is about 300 300 m/sm/sat room temperature (300 K). at room temperature (300 K). The speed at 1200 K would be aboutThe speed at 1200 K would be aboutA: 600 A: 600 m/sm/sTemperature increases by factor of 4, Temperature increases by factor of 4, so KE increases by same factorso KE increases by same factorKinetic energy proportional to vKinetic energy proportional to v22, so , so doubling v multiplies KE by 4doubling v multiplies KE by 4Judah Levine, 3070L3 8Types of Energy Types of Energy ----22Gravitational potential energy:WW in pounds, h in feet, potential energy in ft-lbshWJudah Levine, 3070L3 9Types of Energy Types of Energy ----22Gravitational potential energy:MgM in kilograms, h in meterspotential energy in joulesg= 9.8 m/s2hMgJudah Levine, 3070L3 10Types of Energy Types of Energy ----33Electrical potential energy:⎯+eforceCurrent in external circuitJudah Levine, 3070L3 11Types of Energy Types of Energy ----44Chemical potential energy:C + O2CO2+ EnergyEnergy comes from re-arrangement of orbitalelectrons – nuclei of atoms are not involvedJudah Levine, 3070L3 12Types of Energy Types of Energy ----44Chemical potential energy:C + O2CO2+ EnergyEnergy appears as KE of the product(s)Products are “hot”Energy transferred by collisionsJudah Levine, 3070L3 13Types of Energy Types of Energy ----44Chemical potential energy:C + O2CO2+ Energy10-18joule for each atom of carbonLump of coal has about 1025atoms10-18×1025=107joules=7×106ft-lbsRaise 3000 lb car by 2300 ft.(Assuming 100% efficiency)Judah Levine, 3070L3 14Types of Energy Types of Energy ----44Chemical potential energy:1 Jelly donut (250 Calories)CO2+ H2O + Energy250 Calories × 4000 joules/Calorie = 106joulesConverted to potential energy=MghM=60 kg, g=9.8 m/s2H= 106/600= 1600 m = about 5000 ftBiological mechanism needed for efficiencyJudah Levine, 3070L3 15Types of Energy Types of Energy ----55Energy – mass equivalence:E= mc29×1016m in kilograms, c in m/sE in joulesJudah Levine, 3070L3 16Types of Energy Types of Energy ----66Electromagnetic energyEnergy carried in electric and magnetic fieldstravels through vacuumconsidered primarily as a transport
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