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Homework Help: Actual displacement of a wave particle

  1. Dec 12, 2013 #1
    1. The problem statement, all variables and given/known data
    The end of a stretched string is forced to vibrate with a transverse displacement with A= 0.30 m and ω = 9.0 rad s-1. If the tension of the string is T = 4.0 N, and the mass per unit length is µ= 1.250 g m-1, calculate

    (a) the wave velocity,

    (b) the frequency of oscillation,

    (c) the wavelength, and

    (d) the displacement of the string at x = 2.0 m from the source at the time t = 100 ms after the oscillation commences.
    Assume that the wave is travelling from left to right.

    The attempt at a solution
    a.) v=√(T/μ) giving me a wavespeed of 56.6 ms-1
    b.)ω=2∏f giving me a frequency of 1.43 Hz
    c.)v=fλ giving me a wavelength of 39.6 m
    d.)This is where I'm stuck :( I would think of using the equation vertical displacement,
    y=Asin(kx-ωt) except I don't know how to find k
    Any help appreciated.
  2. jcsd
  3. Dec 12, 2013 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    If you put t=0, then you have y=Asin(kx)
    ... then when x=0, y=0 right?
    ... when x=λ, what is y equal to (hint: definition of wavelength)?
    ... therefore what is kλ equal to?
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