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# Physics/Can sound waves implode or crush objects?

Question
QUESTION: Hi. I am genuinely curious and am doing research on this. You can explode objects using sound waves-  bombarding objects with sound waves with the same frequency as the resonant frequency of the object. Can you use sound waves to implode or crush objects? Would these sound waves have to have the same frequency as the object's resonant frequency to make this happen? Please help- thank you.

ANSWER: Well, a couple of things first, since it's more complex and more simple than that all at the same time.  Some objects don't really have a strong resonant frequency (by strong, I mean that they don't resonate very well at all), some objects have a large number of them.  That frequency may depend on how you're bombarding it with sound, as well, it's not necessarily symmetric.

The simple answer to your question, however, is that sound can crush objects without being at some resonant frequency.  The perfect example is the crushing of very hard kidney stones without harming the body around them using sonic shock waves.  http://www.webmd.com/kidney-stones/extracorporeal-shock-wave-lithotripsy-eswl-fo  Sound wave lithotripsy is common and has been done for a long time.  If you're doing research on this topic, I would start there...that research is extremely mature and advanced.

---------- FOLLOW-UP ----------

QUESTION: Interesting, and thank you for the quick response.

I know you can explode an object with sound waves externally, as when opera singers break wine glasses. The sound waves emitted have the same frequency and the resonant frequency of the glass and the glass shatters and explodes.

Can sound waves crush or implode an object if the sound is affecting the object externally?

How do they generate sound shock waves on such a small scale? Usually when people think of sonic shock waves they think of sonic booms, and sonic booms are usually massive.

How do you modify sound waves to impact a segmented object?
I know that segmented objects don't resonate well and and the sound waves just overlap, amass inside the segmented object and dissipate. How can the sound waves be modified so that the segmented object will be impacted by it, so it will shatter and explode, or implode?

Also, if you want to explode or implode a curved object, how can you affect a curved object with sound waves? Like a U-shaped joint? I don't know if curved objects resonate very well, at all.

ANSWER: I think the first one of these is the most informative, but it's long:

I would have assumed the machine works with a piezoelectric transducer to emit the sound, they're quite powerful, but the youtube video says that the shock wave is actually generated by sparks.  I'm not a sound engineer, so the design of waveguides and such are probably industrial secrets.  The design of such machines is mathematically complex.  Shock waves are generated in nature by many things, including animals like the mantis shrimp (which uses them as a weapon to crush shells of its prey).

Shock waves are not quite like normal oscillatory sound waves.  They're concentrated energy fronts, which can move very fast compared to normal sound waves if the energy involved is very high (nuclear weapons, etc).  This has now gotten into a very specific subdiscipline that is pretty far out of my area of expertise.  You're better off asking a sound engineer about shock waves.  It's a vast field of research, that encompasses everything from sonic booms to ultrasonic jewelry cleaners, you'll need to make your questions more specific or take some pretty advanced engineering classes to go further in a general sense of understanding.  Specific questions might be answerable by me or someone with less sound-specific experience.  General understanding will require a muuuuch more intense grounding in formal engineering.

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QUESTION: Okay, I'll look at those links. Do the other questions I asked have to do with sonic shock waves? The ones about using and modifying sound waves to impact a segmented object and a curved object? Or could you use normal sound waves for this? Please let me know- thank you.

You can "impact" an object with sound waves, sure...but what are you trying to do with it?  If you focus a sound wave towards an object, you can hit it.  If you're trying to apply forces to do something to it, that's much more specific, and probably involves shock waves.  Again, you'll need a more specific question, the question is too general.  And in order to ask a more specific question, you'll probably need a more specific expert whose area is sound wave propagation.

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#### Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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