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Homework Help: Very fundamental qn on waves

  1. Sep 1, 2005 #1

    Wen

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    2 sinusiodal waves are defined

    y1=2sin(20x-32t)
    y2=2sin(25x-40t)

    what is the phase difference between this two waves at point x=5 and t=2s. all length in cm.

    I sketch the graph y/x and y/t and both have their max amplitude at x=3.2 , and t=3.125s.

    so what is the different in phase? Arn't them in phase?
     
  2. jcsd
  3. Sep 1, 2005 #2

    Galileo

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    The phase is simply the argument of the sinusoid wave. For y1 and y2 at x=5 and t=2 you get: y1=2sin(36) and y2=2sin(45). So the phase differerence is 45-36=9.

    More generally, their phase difference at a certain point x is (25x-40t)-(20x-32t)=5x-8t.
     
  4. Sep 1, 2005 #3

    Wen

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    but the answer is 156 degree?
     
  5. Sep 1, 2005 #4

    mukundpa

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    Taht's why one should always use Proper units. The phase difference is in radiuns.
    9 radiuns = 9*180/pi = 515.66 deg. = (360 + 155.66) deg
     
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