(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I need to find the steady state displacement amplitude for a driven harmonic system.

2. Relevant equations

mass (m) = .5kg

stiffness (s) = 100 N/m

mechanical resistance (Rm) = 1.4 kg/s

force (f) = 2cos5t

3. The attempt at a solution

What I know:

angular freq (w) = 5 rad/sec

magnitude of force (F) = 2N

necessary diff. eq.: m[itex]\ddot{x}[/itex] + Rm[itex]\dot{x}[/itex] + sx = Fexp(iwt)

complex displacement: x=[itex]\frac{1}{iw}[/itex][itex]\frac{Fexp(iwt)}{Rm + j(wm-s/w)}[/itex]

I can ignore exp(iwt) because |exp(iwt)|=1.

So I need to find the magnitude of the complex displacement (while ignoring exp(iwt)) but I just don't remember how to deal with complex numbers. I've basically got all the values for what's in the complex equation I just don't know what to do with it!

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# Homework Help: Driven Harmonic Sys. Displacement Amp.

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