Discussion in 'Homework Help' started by Amanda_Riley, Apr 2, 2011.

1. ### Amanda_Riley Thread Starter New Member

May 12, 2010
22
0
I have two 1st order transfer functions of:

5/s+5 and 10/s+10

when they are cascaded you get 50/(s+5)(s+10) if an impulse function of 1 is input.

How is the output 10e^-5t - 10e^-10t?

2. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
By cascaded you mean connected in series? If yes, then the Transfer Function that occurs is independent of the input of the system.

I really messed up this one. The correct answer is given by the method explained by the post next to mine.

Last edited: Apr 2, 2011
3. ### dewasiuk New Member

Feb 14, 2011
24
0
If you use partial fraction expansion, you can easily take the inverse laplace transform to transform your terms to the time domain.

50/(s+5)(s+10) = a/(s+5) + b/(s+5)

Solve for both a and b, and then you can then easily apply laplace techniques, if you've already learned them.

My solution: http://img864.imageshack.us/i/laplace.jpg/

Table of transforms: http://www.intmath.com/Laplace-transformation/Table-laplace-transforms.php

Last edited: Apr 2, 2011
4. ### Amanda_Riley Thread Starter New Member

May 12, 2010
22
0
Thank you for this x