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1、OBJECTIVESModel the simple harmonic wave with a mathematical equation;Understand the physical meaning of wave equations;Calculate the phase difference,wave speed.6-3 Wave equationsCollege Physics II平台标位置预留For a source of SH oscillation with w,the traveling in+x direction with v&oscillating/y,no abso
2、rption in the medium(A for all elements).Maths expression of traveling wavesCollege Physics II平台标位置预留The motion equation at point P:College Physics II平台标位置预留Approach I:phase differenceApproach IICollege Physics II平台标位置预留Point P repeats the oscillation of the wave source.The time the oscillation stat
3、e at point O travels to point P:The oscillation at P at time t=x/vThe oscillation at O at time t=0The oscillation at P at time tThe oscillation at O at time t-x/vNeglecting the subscript P,we have equivalent expressions for SH wave:andCollege Physics II平台标位置预留Wave equationsThe physical meaning of wa
4、ve equation:Time period TT(1)Fixed x,corresponding to the oscillating curve of medium element at position x,i.e.y(t,xo).(2)Fixed t,corresponding to the y-x curve at to.Space period College Physics II平台标位置预留At t0,the phase of element x2 is behind that of x1:Wave-path differenceCollege Physics II平台标位置
5、预留The origin O can be arbitrary(may not be the wave source).For different O,the expression for same wave is different.(3)If the wave moves along-x axis,thenNote:College Physics II平台标位置预留+:The waves travels to x direction;:The wave travels to+x direction.The wave speed vTo ensure the wave form retaining,the phase must remain a constant:Wave speed is the phase speed distance of an oscillatory state propagating in a unit-time or one wavelength per period.College Physics II平台标位置预留wave pattern at twave pattern at t+tv
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