Mookie Riffic

This is going to be a new segment, hopefully daily. But daily is a kind of iffy thing with me. Heh. But anyway, pretty much I'll answer a random science question. I'll answer one that someone’s emailed me (mookie -at- mookieriffic.mu.nu) or I'll grab one of my "Handy Answer Science Books" and pick a random page and question. If its an Emailed question, you might want to take the answer with a grain of salt. But with out further ado:

Crystal wine glasses can shatter when resonating, but can they make music?
If the energy of a resonant standing wave is large enough, a crystal wineglass can shatter quite easily, but when the amplitude is smaller, the wineglass can produce a sound instead. Take, for example, a person rubbing his finger around the moist lip of a crystal wineglass. The glass seems to sing or hum. The humming is caused by the work the finger does on the glass: the rubbing of the glass causes it to achieve a standing wave pattern and perhaps resonate. The resonating molecules in the glass generate enough energy to vibrate the surrounding air and create a steady humming sound.

The frequency of the sound can be adjusted the same way that the frequency in an organ pipe can be adjusted--by changing the height of the air column, or in the case of the wine glass, by adding to taking away some of the liquid inside the glass.