Need help simplifying equation to find the laplace transform of it

Click For Summary
The discussion centers on simplifying two equations from an electrical circuit with two loops to find the Laplace transform. The equations involve currents I1 and I2, resistances R1 and R2, and a capacitor, with the goal of determining the step response using MATLAB. The user is struggling with the integrals present in the equations and is considering differentiating them to simplify the process. There is a suggestion that taking the Laplace transform first may also be a viable approach. Ultimately, the user seeks confirmation on the setup of their differential equations and guidance on relating the output voltage across R2 to the input.
formulajoe
Messages
177
Reaction score
0
there are two loops in an electrical circuit. I've got two equations and two unknowns.
here are the equations

v(t) = I1*R1 + 1/c*int(I1*dt) - 1/c*int(I2*dt) - first loop
0 = LdI2/dt + R2*I2 - 1/c*int(I1*dt) + 1/c*int(I2*dt) - second loop

the capacitor is in the branch between the two loops.

Im drawing a blank on this. I need to simplify into one equation so I can find the laplace transform of the one equation.
the goal is to find the step response of the system using matlab.
 
Physics news on Phys.org
You'll want to differentiate both equations first, to get rid of those god awful integrals.

I need to simplify into one equation so I can find the laplace transform of the one equation.

There's nothing wrong with taking the Laplace transform first and then simplifying.
 
can i get a confirmation that i set up those differential equations properly? I am having some trouble with this still. if i differentiate, than i get derivative of the input. I am trying to find the output voltage which is across the R2 resistor.
 
im still having trouble with this problem. I've tried multiple methods including differentiation and solving for a variable and plugging it into the first equation but I am still where i started the other day. I am trying to find an equation that relates the output voltage across R2 to the input. I am confident my beginning equations are correct, but i don't know where to go from there.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

Replies
4
Views
1K
Replies
10
Views
3K
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 6 ·
Replies
6
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K