Engineering Laplace Transform on RC circuit

AI Thread Summary
The discussion centers on solving a Laplace transform problem for an RC circuit, specifically finding the voltage v(t) across a capacitor after a switch is closed. Participants express confusion about the initial conditions, particularly V(0'), which is suggested to be assumed as zero despite the lack of explicit information in the problem statement. The need for partial fraction expansion to simplify the equation is emphasized, with suggestions to reference inverse Laplace tables for guidance. Participants discuss algebraic steps to isolate variables A and B using specific values for s to facilitate solving the equation. The conversation highlights the importance of clear problem statements in physics homework.
CoolDude420
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Homework Statement


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Homework Equations

The Attempt at a Solution


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I'm kind of lost now, how do I go about getting this into the right form for partial fraction exapnsion. And also what do I do with the V(0'). There was no information given about it.
 

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What is the problem statement? It is not clear from what you supplied. Also, why do you have an initial charge on the capacitor when the switch was initially open?
 
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The problem is to find v(t) for t>0. The diagram is a series combination of a voltage source E, resistor R and capcitance C. Where v(t) is the voltage across the capacitor. The step function diagram is for E not v(t)
 

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CoolDude420 said:
I'm kind of lost now, how do I go about getting this into the right form for partial fraction exapnsion.
Algebra.
And also what do I do with the V(0'). There was no information given about it.
It's reasonable to assume it's equal to 0, though the problem statement really should have included information about it.
 
vela said:
Algebra.

It's reasonable to assume it's equal to 0, though the problem statement really should have included information about it.

Any idea on what next "algebra" step to take?
 
take a look at any inverse laplace table. You need to find a way to get your system into one of those forms.
So...

E/C / [ S * (Rs+1/C) ] = A1 + [A2 / S] + [A3 / (Rs+1/C)]

Solve for A and B. How do you do that. Try setting s=0 and s= -1/(RC), which will cancel out the values
 

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