Finding ZIR given a diff eq

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In summary, the task is to calculate the zero-input response (ZIR) for a system described by the differential equation 2y' + 3y = 2x' + x(t-1), with an initial condition of y(0-) = 5. The approach involves laplace-transforming the equation, finding the transfer function H(s), and then inverting back to the time domain. However, there may be a mistake in the initial transform or in the overall method. The complete response is the sum of the zero-state response and the zero-input response.
  • #1
MooseBoys
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Homework Statement


Calculate ZIR(t) for the system described for the following differential equation, where the initial condition is y(0-) = 5:


Homework Equations


2y' + 3y = 2x' + x(t-1)


The Attempt at a Solution


I'm pretty sure we're supposed to laplace-transform it, then find Y/X = H(s) then inverse back to time domain.
2*(s*Y - 5) + 4*Y = 2*(s*X) + X*exp(-s)
cannot be solved for Y/X, which makes me think I somehow messeed up the initial transform, or perhaps the method altogether
 
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  • #2
MooseBoys said:

Homework Statement


Calculate ZIR(t) for the system described for the following differential equation, where the initial condition is y(0-) = 5:


Homework Equations


2y' + 3y = 2x' + x(t-1)


The Attempt at a Solution


I'm pretty sure we're supposed to laplace-transform it, then find Y/X = H(s) then inverse back to time domain.
2*(s*Y - 5) + 4*Y = 2*(s*X) + X*exp(-s)
cannot be solved for Y/X, which makes me think I somehow messeed up the initial transform, or perhaps the method altogether
For the ZIR you must have no imput. So, you must solve
2y´ + 3 y = 0 with y(0) = 5
For the zero state response you solve
2y´ + 3y = 2x´+ x(t-1)
The complete response is the sum of the two.
 
  • #3


I would first commend the student for their attempt at solving the problem using Laplace transforms. This is a valid approach and shows a good understanding of the concept. However, I would suggest checking the initial conditions and making sure the Laplace transform was done correctly. It is also important to double check the algebra when solving for Y/X. If the problem persists, I would recommend seeking assistance from a teacher or classmate to ensure accuracy in the solution. Additionally, it may be helpful to review the Laplace transform method and practice more problems to gain a better understanding of the concept.
 

1. What is a "diff eq"?

A "diff eq" or differential equation is a mathematical equation that describes how a quantity changes over time or in relation to other variables. It includes both the dependent variable, which is being studied, and the independent variable, which is used to predict the behavior of the dependent variable.

2. How do you find ZIR using a diff eq?

To find ZIR (zero input response) using a diff eq, you need to first set the right side of the equation to 0, indicating that there is no input. Then, solve the equation for the dependent variable to determine its behavior over time without any external influences.

3. What information is needed to use a diff eq to find ZIR?

In order to use a diff eq to find ZIR, you will need the initial conditions of the system, such as the starting value of the dependent variable and any known values of the independent variable. You will also need to know the form of the differential equation, which can be determined based on the system being studied.

4. What is the importance of finding ZIR using a diff eq?

Finding ZIR using a diff eq allows us to better understand the behavior of a system without any external influences. This information can be useful in various fields such as physics, engineering, and economics, as it helps to predict the long-term behavior of a system.

5. Are there any limitations to using a diff eq to find ZIR?

Yes, there are some limitations to using a diff eq to find ZIR. These equations are based on certain assumptions and may not accurately represent all systems. Additionally, complex systems may require more advanced mathematical techniques to accurately find ZIR.

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