Laplace Transformation Convolution Integral

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The discussion revolves around finding the Laplace transformation of a given function, where the user initially mislabels variables and expresses confusion about the transformation process. The derived expression for Y(s) includes terms that can be simplified, prompting a suggestion to combine certain terms for clarity. The correct answer is provided, which includes a convolution integral involving g(τ). Participants emphasize the importance of rechecking calculations to ensure accuracy in the transformation process. Overall, the thread highlights common challenges in applying Laplace transformations and the need for careful algebraic manipulation.
bmb2009
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Homework Statement



I need to find the laplace transformation of the following function (and it's ok to leave it expressed as an integral). After doing the initial steps and algebra I got

Y(s)= g(t)/(s+2)^2 + 7(1/(s+2)^2)+ 2(1/(s+2)^2)

the answer is y(t)=2e^-2t +te^-2t +∫(t-τ)e^-2(t-τ) g(τ) dτ

We are allowed to use laplace transformation tables but what I don't understand is how to factor the terms in the Y(s) equation into a form which correlates in the base transformations. Any help would be great. Thanks



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The Attempt at a Solution

 
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bmb2009 said:

Homework Statement



I need to find the laplace transformation of the following function (and it's ok to leave it expressed as an integral). After doing the initial steps and algebra I got

Y(s)= g(t)/(s+2)^2 + 7(1/(s+2)^2)+ 2(1/(s+2)^2)

the answer is y(t)=2e^-2t +te^-2t +∫(t-τ)e^-2(t-τ) g(τ) dτ

Why is there a ##t## variable in your expression for ##Y(s)##?
 
LCKurtz said:
Why is there a ##t## variable in your expression for ##Y(s)##?

My bad it's G(s) which is not explicitly defined
 
bmb2009 said:
Y(s)= g(t)/(s+2)^2 + 7(1/(s+2)^2)+ 2(1/(s+2)^2)
Is there some reason you didn't combine the last two terms into 9/(s+2)2?

the answer is y(t)=2e^-2t +te^-2t +∫(t-τ)e^-2(t-τ) g(τ) dτ
If this is the answer, you need to recheck your earlier work for errors.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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