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Homework Help: Resonance problem involving Laplace transformations

  1. Sep 2, 2009 #1
    1. The problem statement, all variables and given/known data

    The sine wave [tex] sin(t) [/tex] will only drive the harmonic oscillator [tex] y'' + \omega ^2 y [/tex] into resonance when [tex] \omega = 1 [/tex]. For what values of [tex] \omega [/tex] will the half- and full-wave rectified sine waves drive the harmonic oscillator into resonance.

    2. Relevant equations

    3. The attempt at a solution

    Starting with the half-wave rectified sine wave;

    Taking the Laplace transform of both sides and rearranging for Y(s);

    [tex] Y(s)= \frac{1+e^{-s\pi}}{(s^2+1)(1-e^{-s2\pi})(s^2+ \omega ^2)} + \frac{sy(0)+y'(0)}{s^2+\omega^2}[/tex]

    From here I think I need to find the poles of Y(s) but I am unsure what to do with the [tex] (1-e^{-s2\pi}) [/tex] in the denominator of the first term. Similar problem when looking at the full-wave rectified sine curve.
  2. jcsd
  3. Sep 3, 2009 #2
    Ok, first of all, this is the math part of the forum, so if you want help solving an ODE, you'll have to actually tell us what it is -- we won't necessarily know what you mean simply by giving a physical description.
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