Anonymous

# How can a certain note sung by a singer cause a crystal glass to shatter?

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Covered by a recent episode of Mythbusters.

Sound waves at the right frequency push the sides of the glass at the resonance frequency until so much motion accumulates it breaks.

It's like pushing someone on a swing, you shove at the right times and the person swings higher and higher. The timing of shoves that causes the swing is like a resonance frequency.

This is due to resonance.

If a vibrating force is applied on an object and removed (the object is left free), then the object will vibrate with a frequency known as natural frequency.

An object can have more than one natural frequency.

If a vibrating force is applied continuously on the object (the object is not left free), then the object will vibrate with the frequency of the force that vibrates it.

This is called forced vibration.

If the frequency of the forced vibration is equal to the natural frequency of the object then the latter begins to vibrate with high amplitude of vibration.

This is called resonant vibration.

In the example, one of the natural frequencies of the glass happened to be equal to the sound frequency and hence resonance is set up and glass begins to vibrate enough to break itself.

Yes it can, if the note sung by the singer is at the frequency of the glass and the amplitude is high enough.

Good Luck!

• Mark G
Lv 7

Its called sympothetic harmonics, and how it works is everything has a harmonic frequency that if that frequency is projected (for example sung) at it the object will start vibrating at the same frequency, if you can force the frequency long and hard enough the object will break from due to imprefections and cracks preventing it from generating the frequency any longer.