Where does natural frequency comes from?

[ramzerimar]

I know everything has a natural frequency that is a intrinsic property to the body in question. For example, a string vibrating has the largest amplitudes when it's vibrating near it's natural frequency, and the same thing happens with other things too (like the Tacoma Bridge).

Natural frequencies also play a important role in control systems. Systems have natural frequencies that you have to take into account when you are designing controllers for them.

While I understand reasonably well how natural frequencies "work", I can't really grasp where do they come from. I mean, is there a reason to why every body has a natural frequency? And why systems have large amplitude oscillations when in resonance?

 

[ZapperZ]

The easiest answer is that they come from the boundary conditions.

Zz.

 

[pixel]

It has to do with what wavelengths fit in the given geometry and give rise to resonance. Using the speed of e.g., sound, in the object, the frequency is determined.

 

[ramzerimar]

Is there any book I could refeer to so as to learn more on the subject?