Laplace transform (translation on the s-axis)

In summary, if you are okay with using only translation in the s-axis, then you can use partial fractions.
  • #1
PhysicsCollegeGirl
6
2

Homework Statement


L-1{[(2s-1)]/[(s^2)(s+1)^3]}

Homework Equations


L{f(t)e^(at)}=F(s-a)

The Attempt at a Solution


I have tried million ways but the different exponents in the denominator are throwing me off.
The other problem is that I cannot use partial fractions, the homework instructions require me to use translation in the s-axis.
But now I am thinking that I have to use partial fractions anyway? Can someone just tell me if there is a way to solve it without using partial fractions, and I will keep at it. If there is not, I can move on with my life in peace. Thank you!
 
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  • #2
PhysicsCollegeGirl said:

Homework Statement


L-1{[(2s-1)]/[(s^2)(s+1)^3]}

Homework Equations


L{f(t)e^(at)}=F(s-a)

The Attempt at a Solution


I have tried million ways but the different exponents in the denominator are throwing me off.
The other problem is that I cannot use partial fractions, the homework instructions require me to use translation in the s-axis.
But now I am thinking that I have to use partial fractions anyway? Can someone just tell me if there is a way to solve it without using partial fractions, and I will keep at it. If there is not, I can move on with my life in peace. Thank you!
I haven't worked it myself, but judging from what the problem looks like, I would write it as$$
\frac{2s-1}{s^2}\cdot \frac 1 {(s+1)^3}$$and use the convolution of the inverses of the two fractions. The second one would give you a chance to use your translation formula.
 
  • #3
PhysicsCollegeGirl said:

Homework Statement


L-1{[(2s-1)]/[(s^2)(s+1)^3]}

Homework Equations


L{f(t)e^(at)}=F(s-a)

The Attempt at a Solution


I have tried million ways but the different exponents in the denominator are throwing me off.
The other problem is that I cannot use partial fractions, the homework instructions require me to use translation in the s-axis.
But now I am thinking that I have to use partial fractions anyway? Can someone just tell me if there is a way to solve it without using partial fractions, and I will keep at it. If there is not, I can move on with my life in peace. Thank you!

I doubt that you have tried more than 10,000 ways. Anyway, if I were doing it I would first expand it into partial fractions, then use the "translation" property on 3 of the 5 terms.

Whether that is OK depends on whether your instructions imply that you must use only the translation property and nothing else, or whether it just requires you to use translation somewhere in the solution. That is something only you can decide.
 
Last edited:

Related to Laplace transform (translation on the s-axis)

1. What is a Laplace transform?

A Laplace transform is a mathematical tool used to analyze signals and systems in the time domain. It converts a function of time into a function of a complex variable, s, which represents frequency. This allows for easier analysis and solving of differential equations.

2. How does translation on the s-axis work in the Laplace transform?

Translation on the s-axis involves shifting the s-domain graph of a function to the left or right by a certain amount. This is done by multiplying the original function by e^-as, where a is the amount of translation. This translation affects the location of poles and zeros on the s-plane and can be used to manipulate the response of a system.

3. What is the significance of translation on the s-axis?

Translation on the s-axis is significant because it allows for the manipulation of a system's response. By shifting the s-domain graph, the location of poles and zeros can be changed, which can affect the stability, frequency response, and other characteristics of a system. This is useful in control systems and signal processing.

4. How is translation on the s-axis related to the inverse Laplace transform?

The inverse Laplace transform is used to convert a function in the s-domain back to the time domain. Translation on the s-axis can affect the shape and location of the s-domain function, which in turn affects the inverse Laplace transform. By understanding the translation on the s-axis, one can better understand the behavior of a function in the time domain.

5. What are some practical applications of translation on the s-axis in engineering and science?

Translation on the s-axis is commonly used in engineering and science for system analysis and control. It is used in the design of filters, control systems, and signal processing algorithms. It is also used in fields such as electrical engineering, mechanical engineering, and physics to analyze and manipulate systems in the frequency domain.

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