The volume of water in a glass can indeed affect the frequency of sound it produces when struck or rubbed, as demonstrated in the musical phenomenon of wineglass music.
When a glass is struck or rubbed, it starts vibrating, and these vibrations create sound waves. The pitch or frequency of the sound produced is determined by the speed at which the glass vibrates. In the case of a wineglass, the main factor influencing the speed of vibrations is the volume of water.
As water is added or removed from the glass, the resonant frequency of the glass changes. Resonance occurs when an object vibrates at its natural frequency, which depends on its physical characteristics. When the volume of water is adjusted, it affects the overall mass and shape of the glass, altering its resonant frequency.
As the water level increases, the pitch of the sound produced by the glass decreases. This is because the added water increases the mass of the glass, making it vibrate at a slower rate and producing a lower frequency sound. Conversely, removing water from the glass decreases its mass, causing it to vibrate faster and produce a higher pitch.
By filling multiple glasses with varying amounts of water, it is possible to create a series of glasses that produce different pitches, thus allowing for the creation of a musical scale. By lightly rubbing the rims of the glasses or tapping them with a utensil, one can produce musical notes corresponding to the different water levels in the glasses.