Physics of Metal?

[Tetra]

I don't understand why, when you tap a metal pot lid, it has a really high pitch as well as resonates.

 

I understand (or I think) that if you hit something, it will vibrate, and since a pot lid is a circular membrane, it will cause resonance, but I'm not sure why.

 

And is the pitch just because of the material itself? Or is there some other reason? Does it create longitudinal waves or transverse? So confused. @_@

[swansont]

I don't understand why, when you tap a metal pot lid, it has a really high pitch as well as resonates.

 

I understand (or I think) that if you hit something, it will vibrate, and since a pot lid is a circular membrane, it will cause resonance, but I'm not sure why.

 

And is the pitch just because of the material itself? Or is there some other reason? Does it create longitudinal waves or transverse? So confused. @_@

 

It vibrates because you've perturbed it, and it is not damped particularly strongly. The pitch depends on the composition, size and shape. Sound waves are longitudinal.

[Tetra]

Yes, but why does it keep on echoing? Say if I were tap a metal pot on the edge, or the rim of a (plastic( bucket, the echo woulnd't last as long. Is it reverberation? Or the shape of the object?

 

Maybe using a pot was a bad example. How about a cymbal? I'm guessing the concepts behind them are similar.

[swansont]

It's the damping present in the structure of the material. If all the mechanical vibrations are at the same frequency, you efficiently add the energy into the system, and it has no place to go but emit sound. Sound doesn't have much energy in it, so the vibration lasts a while. If the energy can go someplace else, the vibrations will dissipate.

[Tetra]

Ohh I see. Yeah, I thought it was something really complicated. I didn't think about dampening before, but now that I do, it makes sense. Thanks.