Physics Help Forum (HELP) How to smash ice or glass with sound

 Aug 20th 2014, 03:49 AM #1 Junior Member   Join Date: Aug 2014 Posts: 1 (HELP) How to smash ice or glass with sound Hi everyone! for a marketing campaign we want to shatter ice or glass using sound - like when in films someone screams and all glass windows break..Is this feasible and how would you go by doing it? Any help would be much appreciated! Thanks
 Aug 20th 2014, 05:07 AM #2 Senior Member     Join Date: Apr 2008 Location: Bedford, England Posts: 668 The key is to hit the correct note, the resonant frequency. This is the frequency that the object naturally vibrates at. For example the note a wine glass rings at if you tap it (or wipe a damp finger round the rim, etc...) If you subject the object to a loud enough noise at this precise frequency it will literally shake itself to bits. Note that, for this to work, the object will need to have a well defined resonant frequency. There are apocryphal tales of opera singers who could break wine glasses in this way, but the only demonstration I have seen used an artificial noise source (sine wave generator through a rock-concert style high powered amplifier and speaker).
 Jul 15th 2017, 09:17 AM #3 Senior Member   Join Date: Aug 2010 Posts: 305 The crucial part here is that ice and glass are crystalline, made up of identical crystals. A crystal has a "natural frequency". As a sound wave, with that same frequency, hits the crystal, the crystal will vibrate itself, breaking the bonds that hold the crystals together and so breaking the glass or ice. Of course, the ice or glass has to be very carefully prepared! Most glass, and even more, most ice is made up of crystals of varying sizes and orientations. In order for this to work the glass (and ice) has to be melted and then resolidified (frozen for water) slowly so that the crystals have the time to align and organize into one huge crystal. Also if there are impurities between the crystals, that will damp out the vibrations and prevent this happening. In fact, the very best glass is called "crystal". Pmb likes this.
 Jul 16th 2017, 01:04 PM #4 Physics Team   Join Date: Apr 2009 Location: Boston's North Shore Posts: 1,460 Very nice explanation HOI. Well done!

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