# LAPLACE TRANSFORM HELP (COUPLED SPRING SYSTEM)

Discussion in 'Math' started by Adanovinivici, Jul 14, 2015.

Sep 5, 2014
58
0
Hello All,

Thank you for reading this request. I've come across a laplace transform that I cannot for the life of me correctly take the inverse of. This laplace transform is the solution for the distance of equilibrium of the first mass in an undamped coupled spring system. I'm supposed to obtain a periodic function, but I keep obtaining a hyperbolic cosine. Here is the equation:

F(s)=s*(s^2+2)/(s^4+3*s^2+1)

Please help me understand how I should do this, so I don't go insane. I checked this function with the inverse laplace calculator on wolfram alpha and by some miracle obtained the correct function, so I know this equation is correct but I don't understand why I can't obtain the periodic functions by hand.

Best,

Last edited: Jul 15, 2015
2. ### Jack OwwO New Member

Jun 18, 2015
6
2
It's just a dumb mistake, when you put back the root of your denominator you forgot the minus sign, $(s^2 - u_1)(s^2 - u_2)$
Hope you didn't lost too much time on that. rofl.

Sep 5, 2014
58
0
You don't have to be a jerk. You were right, so thanks for that much.

4. ### Jack OwwO New Member

Jun 18, 2015
6
2
Why was I a jerk ?

5. ### Lool Member

May 8, 2013
117
12
LOL, he interpreted you literally, and does not understand the usual meaning when we say we "made a dumb mistake".

Either that, or he is using reverse language back at you as a joke. hehehe