Need help with Laplace transformations

In summary, Laplace transformations are mathematical tools used to solve differential equations by converting them from the time domain to the frequency domain. To perform a Laplace transformation, one must take the derivative of the function in the time domain and use a specific formula involving integration. These transformations have benefits such as easier analysis and a more intuitive understanding of complex systems, but also have limitations such as not being applicable to all types of differential equations and requiring complex calculations. They are commonly used in various fields such as engineering, physics, and mathematics for tasks such as analyzing electrical circuits and studying control systems.
  • #1
lucox
1
0
I need help with calculation of several Laplace transformations. I'm not sure about following word expressions, which I'll use, as english is not my mother tongue, but I hope It will be understandable. 1. Find transformation to this object:
[tex]f(t) = 3t\sinh^2t - 4\int_{0}^{t}(e^s \cos hs - s^5e^3s - 1)ds[/tex]
I got this result, but I'm not sure about it
[tex]F(p) = \frac{1}{p} - \frac{6p}{(p^2-1)^4} - 4(\frac{p-1}{(p-1)^2-1} - \frac{5}{(p-3)^6} - \frac{1}{p})[/tex]2. Find transformation to this object:
[tex]f(t) = \int_{0}^{t}(4-6s\cos^23s+8\sin2s\cos2s)ds-3\frac{d}{dt}[te^{-2t}\sin3t+\cos^22t][/tex]3. Find source object f(t) related to this transformation:
[tex]F(p) = \frac{p+1}{p^2-2p+2}[/tex]4. Find source object f(t) related to this transformation:
[tex]F(p) = \frac{5p(1-e^{-\frac{\pi}{2}p})}{(p+1)(p^2+4)}[/tex]5. Find transformation of periodic function f(t), where
[tex]f_T(t)=\left\{\begin{array}{cc}3,&\mbox{ if }
t\epsilon \left\langle0,\frac{\pi}{8}\right)\\\sin4t, & \mbox{ if } t\epsilon \left\langle \frac{\pi}{8},\frac{\pi}{2}\right)\end{array} T=\frac{\pi}{2}[/tex]6. Find source object f(t) related to this transformation:
[tex]F(p) = e^{-\pi p} \frac{8}{p(p^2+4)} - \frac{2p^2-2p+8}{p(p^2+4)}[/tex]
*** do I consider it right, that 1,2,5 are normal Laplace transformations and 3,4,6 are the inversed ones ?

Are they not too wild for homework or is this just my feeling ? I'm quite lost in them. Can you help me calculating and explaining the procedure ? I would appreciate any little effort on this. Is here somebody who could help me with this in next 3 hours ? I need to have it done until tomorrow. hmmm

BIG Thanks in advance

Luana
 
Last edited:
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  • #2
1. Your answer is correct.2. The answer is:F(p) = \frac{4}{p} - \frac{6(p^2-1)}{(p^2-2p+2)^2} + \frac{8(p-1)}{(p^2-2p+2)^2} - \frac{3}{2(p^2+4)} + \frac{6}{(p^2+4)^2}3. The source object f(t) related to the transformation F(p) = \frac{p+1}{p^2-2p+2} is:f(t) = e^{-t}\sin\sqrt{2}t + \sqrt{2}e^{-t}\cos\sqrt{2}t4. The source object f(t) related to the transformation F(p) = \frac{5p(1-e^{-\frac{\pi}{2}p})}{(p+1)(p^2+4)} is:f(t) = 5\cos(\frac{\pi}{2}t) - 5e^{-\frac{\pi}{2}t}\cos(\frac{\pi}{2}t)5. The transformation of the periodic function f(t) is:F(p) = \frac{3}{p} + \frac{8}{(p^2+4)^2}6. The source object f(t) related to the transformation F(p) = e^{-\pi p} \frac{8}{p(p^2+4)} - \frac{2p^2-2p+8}{p(p^2+4)} is:f(t) = 8e^{-\pi t}\cos(\frac{\pi}{2}t) + (2t-1)e^{-\pi t}\sin(\frac{\pi}{2}t)
 

1. What are Laplace transformations and why are they used?

Laplace transformations are mathematical tools that are used to solve differential equations. They are used to convert differential equations from the time domain to the frequency domain, making it easier to analyze and solve them.

2. How do I perform a Laplace transformation?

To perform a Laplace transformation, you first need to take the derivative of the function in the time domain. Then, you use a specific formula to transform the function into the frequency domain. This formula involves integration and can be found in most math or engineering textbooks.

3. What are the benefits of using Laplace transformations?

Laplace transformations allow for easier analysis and solving of differential equations, especially those involving complex systems. They also provide a more intuitive understanding of the behavior of a system, as the frequency domain provides information about the system's response to different input signals.

4. Are there any limitations to using Laplace transformations?

Yes, there are some limitations to using Laplace transformations. They may not be applicable to all types of differential equations, and the inverse Laplace transformation may not always exist. Additionally, the use of Laplace transformations may not be practical for certain real-world systems due to the complexity of the calculations involved.

5. How can I use Laplace transformations in my research or work?

Laplace transformations are commonly used in various fields such as engineering, physics, and mathematics. They can be applied in various scenarios, such as analyzing electrical circuits, solving mechanical problems, and studying control systems. If you are working on a project that involves differential equations, it is likely that Laplace transformations can be useful in your research or work.

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