复旦大学《大学物理》课件（英文）-第10章 Angular momentum(1).pdfVIP免费

Chapter10Angularmomentum10-1Angularmomentumofaparticle1.DefinitionConsideraparticleofmassmandlinearmomentumatapositionrelativetotheoriginoofaninertialframewedefinethe“angularmomentum”oftheparticlewithrespecttotheoriginotobe(10-1)→P→r→L→→→=PrLxzym→P→rItsmagnitudeis(10-2)whereisthesmalleranglebetweenand,wealsocanwriteitasNotethat,forconvenienceandareinxyplane.sinrpL=⊥⊥==rpprL→P→r→P→r2.TherelationbetweentorqueandangularmomentumDifferentiatingEq(10-1)weobtain(10-6)Here,the→→→→→→→→==+=FrdtPdrPdtrddtLd→→=vdtrd0==→→→→PvPdtrdandEq(10-6)statesthat“thenettorqueactingonaparticleisequaltothetimerateofchangeofitsang...