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Homework Help: Analyzing a wave

  1. Sep 2, 2007 #1
    1. The problem statement, all variables and given/known data

    http://photo.ringo.com/230/230997145O975467146.jpg [Broken]

    http://photo.ringo.com/230/230997145O975467146.jpg [Broken]

    2. Relevant equations

    V(string) = √(Tension of string/μ), where μ = denisty

    D(x,t) = A sin (kx - ωt + Φ)

    3. The attempt at a solution

    I found the maximum displacement as 2, found from the given equation

    The third part seemed to be the next simplest, so using v=ω/k, I calculated 638/12.57 as the speed, which was incorrect

    To my knowledge, this speed is needed to calculate the tension of part 1
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Sep 2, 2007 #2


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  4. Sep 2, 2007 #3
    i guess it is possible, but that is the exact question copied word-for-word
  5. Sep 2, 2007 #4
    what does d(D(x,y))/dt means?
  6. Sep 23, 2007 #5
    I just realized that the third part is not required to complete the first part,

    using v=ω/k, and plugging this v into

    V(string) = √(Tension of string/μ), where μ = denisty;

    I get an answer of 12880.7, which is essentially 12.9 *103....the answer however is simply 12.9....

    where am i going wrong?

  7. Sep 23, 2007 #6
    I thought it had to do with the amplitude being in centimeters, so I divided by 100, but that still is 129 not 12.9...
  8. Sep 23, 2007 #7


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    Make sure all units are consistent. The linear mass density is 5 g/ m as opposed to 0.05 g /cm or 0.005 kg/m. Perhaps that is where one is off by 3 or 1 order of magnitude depending on the values one uses. Tension should be in Newtons (for SI/mks).
    Last edited: Sep 23, 2007
  9. Sep 23, 2007 #8
    thanks!, makes sense
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