Laplace Transform of an equation with more than one variable

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SUMMARY

The discussion focuses on finding the Laplace transform of the equation du/dt = -0.0291*u + 0.0629*w - 32*theta + (0.2/m)*deltaT, where u and w are independent variables. The user struggles with the application of the Laplace transform to this equation, particularly in handling multiple variables. It is established that to solve for both u and w, two equations are necessary to derive their respective Laplace transforms. The response emphasizes the importance of treating theta and deltaT as constants during the transformation process.

PREREQUISITES
  • Understanding of Laplace transforms and their properties
  • Familiarity with differential equations
  • Knowledge of transfer functions in control systems
  • Basic concepts of independent and dependent variables in mathematical modeling
NEXT STEPS
  • Study the derivation of Laplace transforms for systems of equations
  • Learn about transfer functions and their applications in Simulink
  • Explore the implications of treating constants in Laplace transforms
  • Investigate methods for solving coupled differential equations
USEFUL FOR

Students and professionals in engineering, particularly those working with control systems, differential equations, and mathematical modeling. This discussion is beneficial for anyone needing to apply Laplace transforms to equations involving multiple variables.

Aeana
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Hey guys, I'm really struggling with an equation that I have to use for a piece of coursework. I think I'm missing something really basic but I can't seem to get past it and wondered if somebody else could help.

I want to know if it's possible to find the Laplace transform of the following:

du/dt=-0.0291*u+0.0629*w-32*theta+(0.2/m)*deltaT

I've tried everything I can think of including taking the Laplace transform of each variable and then adding them together at the end which I don't think works. I've searched everywhere I can think of for an answer to my problem but I've found nothing.

Can somebody please help me?
 
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Are you saying that u and w are independent variables? Then one equation is simply not enough to determine two variables. If you had two equations, then you could take the Laplace transform of both sides of both equations to get two algebraic equations in the Laplace transforms of u and w.

Assuming that the theta and deltaT are constants, taking the Laplace transform of both sides of this equation, and writing U(s) and W(s) for the transforms of u(t) and w(t), respectively,
sU(x)- u(0)= -0.0291U(s)+ 0.0629W(s)+ ((0.2/m)deltaT- 32theta)/s
 
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Thanks for replying HallsofIvy. u and w are independent variables yes, they are derived from other equations which are computed in simulink. However to be able to compute the values for u,w,etc. I must know the transfer function for the equation mentioned previously. It's very messy.
 

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