# Second order circuit - zero imput response

Discussion in 'Homework Help' started by omar-rodriguez, Mar 8, 2016.

1. ### omar-rodriguez Thread Starter Member

Jun 24, 2015
51
2
Hello, I have spent a lot of time trying to understand why I can't do this exercise by two different ways and find the same result.

I have to find Vc1(t) t ≥ 0 by two ways

1. first find the differential equation and then apply laplace transformation
2. second analyzing the circuit directly in the frequency domain

Solution:
1. find the differential equation and then apply laplace transformation

2. analyzing the circuit directly in the frequency domain

as you can see both answers are different and this this makes no sense..... I really don't know why HELP!!!

2. ### anhnha Active Member

Apr 19, 2012
776
48
First, for the integral, you should take limits into account. By the way, why don't you Laplace and solve for I(s) in method 1?

3. ### omar-rodriguez Thread Starter Member

Jun 24, 2015
51
2
I put the initial conditions after transform the differential equation

4. ### anhnha Active Member

Apr 19, 2012
776
48
Here is my result when solve for V1(t):

omar-rodriguez likes this.
5. ### omar-rodriguez Thread Starter Member

Jun 24, 2015
51
2
Great!!, finally I undestood my mistake thank you