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Differential equation with laplace transform and springs

  1. Dec 2, 2014 #1
    1. The problem statement, all variables and given/known data
    I do not know how to find f(t) with the given Ampliture 40 and a=pi
    Untitled.png
    2. Relevant equations


    3. The attempt at a solution
    I have the solution above.

    my set up was 1/2y''+y'+5=f(t)

    1/2S^2* Y(s) + Y(s)+5=f(t)
     
  2. jcsd
  3. Dec 2, 2014 #2

    SteamKing

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    Have you studied periodic functions? Do you know how to obtain the Laplace transform of a periodic function?

    Here is a brief article discussing how:

    http://academic.udayton.edu/LynneYengulalp/Solutions219/LaplacePeriodicSolutions.pdf [Broken]
     
    Last edited by a moderator: May 7, 2017
  4. Dec 2, 2014 #3

    LCKurtz

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    You want the LaPlace transform of f(t) on the right of that last equation. To see how to get the transform of a periodic function, look here:
    http://www.intmath.com/laplace-transformation/5-transform-periodic-function.php
     
  5. Dec 2, 2014 #4
    From the looks of this does amplitude not matter , only the period?
     
    Last edited by a moderator: May 7, 2017
  6. Dec 2, 2014 #5

    LCKurtz

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    Wrong. There is an ##f(t)## in the formula for the transform, so everything about ##f(t)## matters.
     
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