1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Piecewise continuous - step function

  1. Dec 6, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider the following initial value problem:

    y''+4y = 9t, 0<=t<2
    ............0, t>=2

    Find the equation you get by taking the Laplace transform of the differential equation and solve for Y(s)

    2. Relevant equations



    3. The attempt at a solution
    I am just having trouble with the step function:

    Say g(t)= 9t, 0<=t<2
    ...............0, t>=2

    g(t)= (1-u(t-2))9t ???
    = 9t-u(t-2)9t

    So, Laplace{g(t)} = (9-9e-2s)/(s2)

    SO, s2Y(s) + 4Y(s) = (9-9e-2s)/(s2)

    And, Y(s) = (9-9e-2s)/((s2)(s2+4))

    There is something wrong with this. If anyone could help me out that would be much appreciated!! Thanks!
     
    Last edited: Dec 6, 2009
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?