- #1
mcelgiraffe
- 10
- 0
Homework Statement
The problem is given as a piece-wise function f(t)={1, 0≤t<4; 0, 4≤t<5; 1, t≥5}. I am asked to write the function in terms of unit step functions and then find the Laplace Transform of the function. I can do the Laplace if I could ever get the unit step function.
Homework Equations
For a function of the type f(t) = {0, 0≤t<a; g(t), a≤t<b; 0, t≥b}
f(t) can be written as: f(t) = g(t)[U(t-a) - U(t-b)]
The Attempt at a Solution
So, if I follow the given equation, then g(t) would be zero.
f(t) = 0[U(t-4) - U(t-5)] = 0 (for any value of t). This doesn't seem correct.
Then I thought maybe I could re-write it as f(t)={0, 0≤t<4; 1, 4≤t<5; 0, t≥5} and subtract the result from 1 giving:
f(t) = 1 - 1[U(t-4) - U(t-5)]. Evaluating this at t=0, would give 1-[0-1]=2. Wrong again.
I have struggled with what should be a simple problem for way to long. I think I am simply approaching the problem all wrong and have a fundamental lack of understanding. Can anyone nudge me in the right direction and give me an alternate way to approach the problem. I have looked at various sites online, but they only confused me more. Any help at all would be appreciated.