how can a high pitch sound shatter glass but low pitch sounds cannot?
In: Physics
It’s all about vibrations/waves.
Higher pitch means faster vibrations which causes the glass to crack.
Low pitch means slow vibrations and therefore more difficult to crack glass.
If you flick the rim of a wine glass it will ring at a certain pitch. That is the frequency of sound it will most easily break at. If the glass was much bigger it would have a lower resonant frequency and you’d be able to use a lower pitch sound to break it.
It’s about resonance. The frequency has to match the natural resonance of the glass.
It’s a little bit like how getting pushed on a swing makes you swing higher but you have to push at the right time.
A wine glass, despite being pretty rigid, does flex like a spring. The first sound wave arrives at the glass and gives it a tiny nudge. It bends back a little bit in response then springs back. If the next sound wave arrives at just the right moment it pushes it again. This time it flexes a little more and springs back. And again the next sound wave gives it another nudge. Just like with a swing set each push at the right moment adds energy.
Keep the sound at the right frequency and with enough volume and eventually the vibration if the glass exceeds it’s structural integrity and it shatters.
It’s not about high vs low pitch, it’s about matching the resonance of the object.
Not all glass gets shattered the way you are thinking (I’m assuming a glass made of glass), depending of it’s actually composition it behaves differently. But in general a glass that breaks because of a sounds is due to the sound having a frequency tyat “matches” the dimension of the glass and thus makes the glass resonate (similar effect than this famous video of a bridge going full buble gun because it resonates with the wind)
Also an aircraft breaking the wall of sound creates a sound wave so powerful (and in all frequencies) that it basically breaks anything if it’s close enough.
The high pitch sounds vibrate the glass at the resonant frequency which will break the glass most easily. Lower pitch frequencies can absolutely break the glass, they will just have to be much louder.
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