[time-nuts] "Q for dummies"

[ed breya]

If you have a mechanical tuning fork handy, just ding it and note the 
gradual decay. Then wrap a small wad of paper towel on one or both arms, 
with some tape outside (not touching the arms - don't want adhesive 
residue left on there) to keep in place, and repeat. For using a wine 
glass or such, stuff some paper toweling inside for loss. The point is 
to use the same resonator for all examples, and represent the loss with 
something added.

Oops - after I wrote this I looked back at the OP and see that it may 
not be for a live presentation, so no props. If so, the audience may be 
encouraged to try it themselves with the wine glass analogy - easy to do.

Ed