potential)机械能(动能和位能)

1EnergyByYeungChungKuen(05996130)(12/03/2006)RevisedbyMak21.WhatisEnergy?2.BasicDefinitions.3.FormsofEnergy.4.AShortHistoryofEnergy.5.DangerousnessofEnergy.6.RenewableEnergy.7.ResourcesRelatedtoEnergy.Outline3Whatisenergy?Energymakeschange;itdoesthingsforus.Itmovescarsalongtheroadandboatsoverthewater.Itbakesacakeintheovenandkeepsicefrozeninthefreezer.Itplaysourfavoritesongsontheradioandlightsourhomes.Itmakesourbodiesgrowandallowsourmindstothink.…….4BasicDefinitionsAverygooddefinitionofenergyis:Energyistheabilitytodowork.Incommonsense,workisgetthingsdone.Inphysics,‘work’isforcexdisplacement,W=Fs.5FormsofEnergy1.Mechanical(Kineticandpotential)機械能(動能和位能)2.Chemical化學能3.Heat熱能4.Electric電能5.Light光能6.Sound聲能7.Nuclear核能Peoplehavelearnedhowtochangeenergyfromoneformtoanothersothatwecandoworkmoreeasilyandlivemorecomfortably.6PotentialEnergyKineticenergy7MechanicalEnergy(槓鈴)Aweightlifterexertsaforcetoliftabarbell.Thekineticenergyofthebarbellchangestothepotentialenergyofthebarbell.8Workdonebymachine=changesinmechanicalenergyoftheload.9ChemicalEnergy10ChemicalHeat+LightEnergy1112Light/HeatEnergy13Electric/Light/SoundEnergy14LightEnergy15Sound/Light/Heat/MechanicalEnergy16NuclearEnergybyFissionNuclearpowerplantsNuclearfission:Alargenucleussplitsintoseveralsmallnucleiwhenbumpedbyaneutronandenergyisreleasedinthisprocess.Sources:(工業革命),ourenergyneedsweremodest(適度的).20ExamplesForheat,wereliedonthesun--andburnedwood,straw,anddrieddung(糞肥)whenthesunfailedus.Fortransportation,themuscleofhorsesandthepowerofthewindinoursailstookustoeverycorneroftheworld.Forwork,weusedanimalstodojobsthatwecouldn'tdowithourownlabor.Waterandwinddrovethesimplemachinesthatgroundourgrainandpumpedourwater.21B.C.500,000-300,000UseoffireManstartedtousefireahalfmillionyearsago.Ancientpeopleknewthefirethroughlightning,forest-fire,explosionofvolcanoandsoon.Firecanprotectthemfromdangerousanimals,warmtheminacoldnight,lightenthedarknessandhardenearthenware(陶器).Theywantedtomaintainconvenientfiretouseitanytime.Atfirsttheykeptthefirewhichwasoccurredbyforestfirebytransferringtowoodpieces.22ForestFire23Butitwasdifficulttocontrolfirebythismethod.Awisemanthought.Producingfirebyourselvesisthebetterway!“LuxuryisthemotherofinventionManhasinventedthemethodstoproduceandcontrolfiremoreeasily.Useoffire24B.C.5000?Inventionofcartwithwheels.Maninventedanddevelopedtoolscontinuously.But,tocarrytoolsandthematerialswastoughjob.Maninventedcartwithwheelsinordertocarryloadseasily.Thiswasthefirststeptomechanicalenergy“whichdevelopedcivilization(文明)rapidly.25B.C.-3000Traditionalboatwasimprovedtosailboatinordertoutilizewindanddriveboatfaster.Thiswasagreatturningpointinthemeaningthatmanutilizedwindasmotionenergy,aswellaswindmill(風車)whichisusedinsomeareanowadays.26B.C.2000?-WarusingarmsAftermanestablishedcivilizationandmadecity,eachcityhadtheirownarmytoguardtheirpeoplefromenemies.Inthewar,theyusearmssuchasastonebow(弓).Manbegantouseenergyfordestroying.27B.C.600DiscoveryofelectricityMandiscoveredelectricity2500yearsago.Amber(琥珀)whichwasrubbedgeneratedstaticelectricitywhichattractedlightmaterials.Electricenergy“whichismostfamiliartousinthehistoryofenergywasdiscoveredatthattime.Howevermoderntechnologyforcontrollingelectricenergywasestablishedatamuchlatertime,sayuntilVoltainventedtheVoltaiccellat1799.Butmancontinuedtodevelopthetechniquesofutilizingenergynotbeingsatisfied.287thCenturyInventionofwindmill(風車)WindmillisoneofveryimportantinventionsintheMedievalAges(中世紀).Windmillbroughttheimprovementinefficiencyofjobandthespreadoftechnologytooperatesomemachinesatthesametimebyusingcranksandgears.(曲柄)(齒輪)Thedevelopmentofmechanicalenergy“wasacceleratedhereinafter.2916thcentury-TheIndustrialRevolutionandfurtherdevelopment1.Steamengine(蒸汽機)30Thedevelopmentofutilizingtechnologyofmechanicalenergywasacceleratedatthespeedwhichmankindhadneverexperiencedbytheinventionofsteamengine.Steamenginebroughtpeoplerailways,powerplant(發電廠),modernmanufacturingplantsandsoon.Steamengine31Thedevelopmentofshipbuildingtechnology,telegraphiccommunication(電報Marconi1874-1937),railwaytechnology,andtheinventionofairplaneinthefirsthalfof19thcenturymadepeopletocommunicateworldwide2.Birthofinternationalnetwork32Endof19thcentury:BirthofpowerplantInventionofelectriclightbulb(Edison1847-1931)isamilestoneofmodernizationin19thcentury.Electriclightwasrapidlyspreadintheindustrialcountriesaroundtheworldwithincreasingnumberofpowerplants,andtheageofelectricenergyhadcome.33A.D.1914-1918WorldWar1TheFirstWorldWarinwhich32countriesparticipatedwasawarusingtechnologicalarmamentsuchassubmarine,aircraft,carrier,poisongas,machinegun.Manylivesweresacrificedinthewar,showingthedarksideofenergyandtechnology.34A.D.1939-1945WorldWar2TheWorldWar2isaveryimportantmilestoneintheutilizataionofenergy,becausenucleararmswereusedforthefirsttimeinthewar.Itshowsthatenergyandtechnologycandestroythecivilizat