4 ms·

In theory but the energy requirements would probably make that infeasible.

• papreclip 7y ago
  >In theory I don't think so. My understanding is that there's a limit to sound wave amplitude (decibels) beyond which you enter the domain of the shockwave. a shockwave is an irreversible process which couldn't be used to maintain some state the way a standing wave can. Without enough concentrated power, you can't lift an arbitrarily heavy(dense) object If you raise the pressure of the medium, the decibel limit goes up, but air at atmospheric pressure is probably going to fall well short of what you'd need to hover a car
  • adrianmonk 7y ago
    It might just be possible. First of all, if you look at static pressure, obviously hovercraft exist and work. And tornadoes can lift cars off the ground. Even strong winds can. Doing some numbers, my car appears to have a horizontal area of about 7.5 m^2 and a mass of about 1500 kg. With earth's gravity, that means 14700 N spread over 7.5 m^2, which means average pressure of 1960 Pa. Wikipedia says (https://en.wikipedia.org/wiki/Sound_pressure#Examples_of_sound_pressure https://en.wikipedia.org/wiki/Sound_pressure#Examples_of_sou...) that a shock wave happens at 101,000 Pa. So the pressure needed to lift my car would be about 2% of the strongest pressure that can exist in a sound wave. Presumably it's a little more complex than that because sound waves oscillate and can't exert constant pressure. So some factor has to be added for that. But seems like there's about 50X to play with before hitting the limit of shock waves. It's going to be crazy loud, though. Like a gun going off continuously.