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Homework Help: Inverse Laplace

  1. Mar 11, 2009 #1
    1. The problem statement, all variables and given/known data

    This isn't a homework, I'm just trying to recap for a mid-term. Anyways, it's about inverse Laplace transformation and this crap is starting to piss me off! How the heck are you supposed to go from [tex] \frac{ \frac{-U}{s}}{R+sL+ \frac{1}{sC}}[/tex] to [tex]- \frac{2 \sqrt{10}}{ \sqrt{15}}e^{-125t}sin(125 \sqrt{15})[/tex]?

    2. Relevant equations

    The values are: [tex]U= \sqrt{10}, R=1, L=4*10^{-3}, C=1*10^{-3}[/tex]

    3. The attempt at a solution

    My best attempt so far has gotten me to [tex] \frac{-U}{s^2+s(R/L)+(1/LC)}=\frac{- \sqrt{10}}{125 \sqrt{15}} \frac{125 \sqrt{15}}{(s+125)^2+(125 \sqrt{15})^2}[/tex]. I know this is pretty close but not close enough...
  2. jcsd
  3. Mar 11, 2009 #2
    I found it out myself. Instead of [tex] \frac{-U}{s^2+s(R/L)+(1/LC)}[/tex] I should have had [tex] \frac{-U/LC}{s^2+s(R/L)+(1/LC)}[/tex]. This gives me the right answer.
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