I've looked across the internet for an answer to why changing the water level in a wineglass affects the frequency measured when the rim of the glass is rubbed. Here's what I've found so far:
- Adding water to the glass causes the inertia of the glass to increase which causes the frequency of oscillation of the wine glass to decrease, therefore decreasing the frequency at which the air is displaced. This results in a lower-pitched sound.
However, I've seen some people say the standing wave of the air column inside the glass decreases in frequency since the length of it decreases as water is added. As a result, since the oscillations of the air column standing wave are transferred to the wine glass (and to the air), this is what causes the frequency of the sound to decrease. (https://physics.stackexchange.com/a/312048/254292).
I'm not sure which explanation is the primary factor that affects the frequency heard, or if they are in fact related to each other in some way. I'd like to have a single explanation that incorporates both of these concepts.