physics 1 fundamentals module 3 oscillations amp; waves text

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1、PHYS1002Physics1FUNDAMENTALSModule3OSCILLATIONS&WAVESTextPhysicsbyHechtChapter11WAVESMechanicalWavesSections:11.111.211.311.411.5Examples:11.111.211.311.5CHECKLIST•Mechanicalwaves,progressivewaves,travellingwave,medium•Longitudinalandtransversewaves-1•Wavefunctionψ(x±vt),wavespeedv(m.s)-1•peri

2、odT(s),frequencyf(Hz),angularfrequencyω(rad.s),wavelengthλ-1(m),angularwavenumberorpropagationconstantk(rad.m)T=1/fω=2πfk=2π/λv=fλ=λ/T=ω/k•Harmonicwavewavefunctiony(x,t)amplitudeAphaseφtravelingwave2πyxt(,)=±Asin(xvt)=±Asin2(/[]πxλωtT/)=Asin(kx±t)λ(-)wavetraveling+Xdirection,(+)wavetrave

3、ling–Xdirection(Eq.11.3)phasevelocityv=fλ(Eq.11.1)2Energy∝Aa03p1waveswaves110105.doc9:34AM1•Transversewavesonstrings-1wavespeedv(m.s)stringtensionFT(N)lineardensityµ=∆m/∆lFTv=(noderivation)(Eq.11.4)µSpeedofamechanicalwaveisdeterminedbytheinertialandelasticpropertiesofthemediumandnotinanyway

4、bythemotionofthesource.•Reflection,AbsorptionandTransmissionreflectionatafixedandfreeends(Figs.11.3,11.14)transmissionandrefractionNOTESWAVES(λ,f)ANDPARTICLES(p,E)twogreatconceptsofclassicalphysics•Particles&Waves⇒transferofinformationandenergy.•Particle-“tiny”concentrationofmattercapableoftra

5、nsferringkineticenergy.•Waves-LeonardodaVinci-waterwaves-“itoftenhappensthatthewavefleestheplaceofitscreation,whilethewaterdoesnot”.•Wave-broaddistributionofenergyfillingthespacethroughwhichitpasseswithoutthetransferof"material".TYPESOFWAVES•Mechanical(governedbyNewton’sLaws-travelthroughamedi

6、um)-sound,water,onstrings,seismic.•Electromagnetic-electromagneticspectrum:self-propagating.8-1Invacuumc=λf=3.00×10m.sincreasingfrequency(energy)anddecreasingwavelength•Matterwaves-“particles”showwavecharacteristics-interferenceλ=h/pf=E/ha03p1waveswaves110105.doc9:34AM2CLASSIFICATIONOFWAVES

7、Aprogressiveortravelingwaveisaself-sustainingdisturbanceofamediumthatpropagatesfromoneregiontoanother,carryingenergyandmomentum.Thedisturbanceadvances,butnotthemedium.Transversewaves-electromagnetic,wavesonstrings,seismic-vibrationatrig