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1、第五章热力学基础Chapter5thethermodynamicbasis§5-1thefirstlawofthermodynamicsanditsapplicationAsingle,Internalenergy:allmoleculesinanobjecthavenoregularkinetickineticenergypluspotentialenergy(molecularvibrationalpotentialenergy,mutualactingpotentialenergy)・Int
2、ernalenergyRealgas:(twoofthemareindependent)Idealgas:Note:(1)isthesinglevaluefunctionofstate,isdecidedby(a)(only2intheindependentvariable),asthestatefunction,thebeginningandendoftheincrementwithonlytwostates,andhasnothingtodowiththeprocess・Theidealgas
3、isasinglevalueaddedfunctionoftemperature・TheequivaleneeofworkandheatJouleusedexperimentsshow:suchaswaytomakethesystemworkandheattransfertemperaturephaseatthesametime,thetransferofheatandtheworkdonethereisalwaysacertainproportionrelations,namely1calori
4、e二4.18joulesofworkSo,workisequivalenttoheat・Youknowbymechanics・Theworkdonetothesystemistotransferenergytothesystem,andsincetheworkisequivalenttoheattransfer,theheattransfertothesystemalsomeansthetransmissionofenergytothesystem・Conclusion:twowaysoftran
5、sferringenergyaredoneHeattransferNote:althoughthereisanequivalentaspectofworkandheattransfer,thereisadifference・Thedifferenceisdone:themacroscopicdisplacementisachievedthroughtheobject・Theeffectisthetransitionbetweenmechanicalmotionandthenon-regularmo
6、tionofthemoleculesinthesystem・Thatchangestheinternalenergy.Heattransfer:throughmolecularinteraction.Thefunctionisthetransitionbetweenthenon-regularthermalmotionoftheexternalmoleculesandthenon-regularthermalmotionofthesystem・Thatchangestheinternalenerg
7、y.ThefirstlawofthermodynamicsIngeneral,whenthestateofthesystemchanges,theworkandheattransferisoftenatthesametime・There，sasystemthat*sgoingtoheatthesystemtomakeitpossibleforthesystemtobe.Andthesystemisdoingworkfortheoutsideworld,sousingthemathematicalr
8、epresentationoftheprocess,thereare:(6-1)Ontypeisthemathematicalexpressionofthefirstlawofthermodynamics,itshowsthatthesystemabsorbsheatandpartisusedtoincreasetheinternalenergy,parttoworkabroad・:theprocessofsmall(6-2)Thefirstlawofthermodynamicsi
