1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Laplace Transform - Step Functions

  1. Jun 24, 2008 #1
    1. The problem statement, all variables and given/known data
    Please help by explaining in detail how to find the Laplace transform of the function

    f(t) = { 2 0 <= t < 3
    { -2 t >= 3.

    2. Relevant equations

    3. The attempt at a solution
    For the most part I know that U(t-3)(t-3).

    I want to account for the amplitude of 2 like this but I think that I am wrong.

    2-2U(t-3)*-2(t-3). I feel that I'm on the right track but might have set up the problem incorrectly. if I have it set up correctly I think I can go from there but would like directional help please.

    Thank You,

    Lady Ann.
  2. jcsd
  3. Jun 24, 2008 #2


    User Avatar
    Homework Helper

    No I don't think that is correct.

    In general, if

    [tex]f(t)= g(t) \ \mbox{for} \ a\leq t \leq b[/tex] and is zero everywhere else, then

    [tex]f(t) = g(t)[u(t-a) - u(t-b)][/tex].
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook