WavesPAL #5 Damped SHMSlide 3Test Next FridayWhat is a Wave?Transverse and LongitudinalTransverse WaveLongitudinal WaveWaves and MediumWave PropertiesAnnotated Wave EquationWavelength and NumberPeriod and FrequencyWave SpeedSpeed of a WaveVelocityWavesPhysics 202Professor Lee CarknerLecture 6PAL #5 Damped SHMYour view compared to face-on viewMax xMin vMin xMax vWhere v is transverse velocityReal x and v are constant (= xmax and vmax)PAL #5 Damped SHMWhat is r if vmax = 13600 m/s and T = 3.6 days? = 2/T = 2/(3.6)(24)(60)(60) = 2.02 X 10-5 rad/sec What is mass of planet?Gravitational force = centripetal force M = v2r/G = 1.9 X 1027 kgTest Next FridayAbout 15 multiple choiceMostly concept questionsAbout 4 problemsLike PALs or homeworkBring calculator and pencilFormulas and constants provided (but not labeled)Worth 15% of gradeWhat is a Wave? Example: transmitting energy, A sound wave can also transmit energy but the original packet of air undergoes no net displacementTransverse and LongitudinalTransverse waves are waves where the oscillations are perpendicular to the direction of travel Longitudinal waves are waves where the oscillations are parallel to the direction of travel Transverse WaveLongitudinal WaveWaves and Medium The wave has a net displacement but the medium does not This only holds true for mechanical wavesPhotons, electrons and other particles can travel as a wave with no medium (see Chapter 33)Wave Properties The y position is a function of both time and x position and can be represented as:y(x,t) = ym sin (kx-t)Where:ym = k = =Annotated Wave EquationWavelength and Number One wavelength must include a maximum and a minimum and cross the x-axis twice k= 2Period and FrequencyPeriod Frequency We will again use the angular frequency,The quantity (kx-t) is called the phase of the waveWave SpeedSpeed of a Wave y(x,t) = ym sin (kx- t)But we want to know how fast the waveform moves along the x axis:v=dx/dt If we wish to discuss the wave form (not the medium) then y = constant and: e.g. the peak of the wave is when (kx-t) = /2VelocityWe can take the derivative of this expression w.r.t time (t): (dx/dt) = /k = vSince = 2f and k = 2 v = fThus, the speed of the wave is the number of wavelengths per second times the length of
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