Vibrations Problem

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loudog

P.E.
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I never took vibrations, and can't seem to find where the attached problem solution comes from. It's from the NCEES 2001 sample test.

Any advice as to where to look is appreciated. I couldn't come up with the answer from the MERM, Mark's, or Shigley (not saying they're not there).

Thanks for any help,

LP

Problem.jpg

Solution.jpg

 
I never took vibrations, and can't seem to find where the attached problem solution comes from. It's from the NCEES 2001 sample test.

Any advice as to where to look is appreciated. I couldn't come up with the answer from the MERM, Mark's, or Shigley (not saying they're not there).

Thanks for any help,

LP
I don't know much about vibrations either. I'll check with my wife.

 
Ok. Here it is:

This is a damped, free vibrations problem

General solution x(t) = e^-nt(c1 cos wt + c2 sin wt)

This w is the damped frequency, not equal to the natural frequency.

Damped frequency = ((natural frequency)^2 - n^2)^0.5

In your problem damped frequency and n = 3.3

Plug chug

Source MERM

 
Last edited by a moderator:
Nice, thanks so much Power.

I'll look into that and report back! I appreciate your effort.

LP

 
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