Solving Laplace Transform Homework: y''+y = f(t)

In summary, a Laplace Transform is a mathematical operation that transforms a function of time into a function of complex frequency, making it useful for solving differential equations. To solve a differential equation using Laplace Transforms, the first step is to take the Laplace Transform of both sides of the equation and then use algebraic techniques to solve for the unknown function. When solving y''+y = f(t) using Laplace Transforms, it is important to consider special cases such as step or periodic functions and initial conditions. Tips for making the process easier include keeping track of Laplace Transforms, using tables or software, and carefully considering initial conditions and special cases.
  • #1
myusernameis
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Homework Statement



y''+y = f(t)

y(0) = 0; y'(0)=1

f(t) = 1, 0<=t<pi/2
0, pi/2<=t


The Attempt at a Solution


so far, i have


(s^2+1)*L{y} = [tex]\frac{s-e^(-pi/2s)}{s}[/tex] +1

what is next ?
 
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  • #2
myusernameis said:
so far, i have (s^2+1)*L{y} = [tex]\frac{s-e^(-pi/2s)}{s}[/tex] +1

what is next ?

That doesn't look quite right; the Laplace Transform of [itex]f(t)[/itex] is not [tex]\frac{s-e^{-\pi s/2}}{s}[/tex] (although it's close). Double check that calculation.

Once you correct your expression, solve for [itex]\mathcal{L}[y(t)][/itex] and then take the inverse Laplace transform to get [itex]y(t)[/itex]
 

1. What is a Laplace Transform?

A Laplace Transform is a mathematical operation that transforms a function of time into a function of complex frequency. It is particularly useful in solving differential equations in the time domain.

2. How do I solve a differential equation using Laplace Transforms?

To solve a differential equation using Laplace Transforms, you first take the Laplace Transform of both sides of the equation. This will transform the differential equation into an algebraic equation. Then, you can use algebraic techniques to solve for the unknown function.

3. What is the process for solving y''+y = f(t) using Laplace Transforms?

The first step is to take the Laplace Transform of both sides of the equation. This will result in an equation in terms of the Laplace Transform of y. Then, you can use algebraic techniques to solve for the Laplace Transform of y. Finally, you can take the inverse Laplace Transform to find the solution for y.

4. Are there any special cases or conditions to consider when solving this type of equation using Laplace Transforms?

Yes, there are a few special cases to consider. If the function f(t) is a step function, the Laplace Transform will involve the unit step function, u(t). If the function f(t) is a periodic function, the Laplace Transform will involve the Dirac comb function. It is also important to consider the initial conditions of the differential equation.

5. Are there any tips or tricks for making the process of solving y''+y = f(t) using Laplace Transforms easier?

One tip is to make sure to keep track of the Laplace Transform of each term in the equation. This will help simplify the algebraic steps. It can also be helpful to use tables or software to look up the Laplace Transform of common functions. Additionally, it is important to carefully consider the initial conditions and any special cases that may arise.

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