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Homework Help: Finding the wavespeed

  1. Apr 25, 2008 #1
    1. The problem statement, all variables and given/known data
    A transverse wave is represented by the function y = 2.3 sin (1.90 x - 25.0t) meters where y, x and t are in meters, meters and seconds respectively. Determine the wave speed in m/s.


    2. Relevant equations
    x = A_0 sin (kx - vt)


    3. The attempt at a solution
    If it's asking for the wave speed, and according to the formula, the wave speed should be 25 m/s and yet the answer is not that. I don't understand what exactly I'm not getting or how I should proceed from here. Any help would be appreciated, thanks.
     
  2. jcsd
  3. Apr 25, 2008 #2

    alphysicist

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    Homework Helper

    HI Hibiscus,

    The equation that you have in section 2 does not look right. Here are two forms for the wave equation:

    [tex]
    y = A \sin(k x -\omega t)
    [/tex]

    [tex]
    y = A \sin[ k (x-vt)]
    [/tex]

    The equation they give matches the first form, so 25 is the angular frequency.
     
  4. Apr 25, 2008 #3
    Ah. I guess I put it wrong. In the answer sheet, the form you gave is the way in which it appears. It says, y = A_o sin (k (x - vt) and then it says to equate the terms. And I still don't understand how.
     
  5. Apr 25, 2008 #4

    alphysicist

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    So you're given y=2.3 sin (1.90 x - 25.0t)

    Rewrite it so it fits the form y = A sin[ k (x - v t) ]

    So what do you have to do to (1.9 x - 25.0 t) to get it in the form

    k ( x - v t)


    (Or since you know [itex]\omega[/itex] you can find how v and [itex]\omega[/itex] are related. It's really the same thing either way you solve it.)
     
  6. Apr 25, 2008 #5
    Ah! Got it! Thank you! =D
     
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