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 [DPRG] Measuring Speed of sound in a liquid Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: [DPRG] Measuring Speed of sound in a liquid Next message: [DPRG] Measuring Speed of sound in a liquid Subject: [DPRG] Measuring Speed of sound in a liquid From: Ken Comer me at kencomer.com Date: Fri Sep 3 15:50:53 CDT 2004 ```> >Why measure speed > >Are you looking to id what the liquid is or the purity or something? > >Or do you just need to measure the presence of liquid? > >A u-shaped fiber optic will give you a "distressed Liquid" > >sensor with some accuracy or transmittance, and somewhat > >inert to acids, etc.! > >Could you measure light to get the results, and use glass > >or crystal windowed pvc fittings? > >Brain storming. Let me preface this with a clear warning that I only have two semesters of college physics, that it was 20 years ago, and that my interests were less to do with mechanics at a macro scale that wasn't at least hundreds of light-seconds worth of "macro" than the dark-haired woman in the third row. I remember as much about her as I do about physics, and I can't even recall her name. YHBW. That being said, how's this for a brainstorm: when all's said and done, a "sound wave" is nothing but a bunch of compression waves back-to-back. In its basic form, just one oscillation has the same properties as a sound wave. It seems to me that you could have a chamber with a fixed end and an end that can could move, and a blade that chop down. The blade goes spl-thunk, the liquid goes sloosh, then the movable end moves a finite amount of time later. The distance from the blade and the initial position of the movable end is known. Measure the amount of time that it takes for the movable end to move, divide by distance; et voilá, the quotient is the speed of sound. All of the pieces involved in this method are pretty minimalist and can be as durable as you like without sacrificing precision. The shape of the tank and initial stillness might throw slop into the measurement, but a little more sophistication in tank and wave-generator can help dampen errors and increase accuracy. The reason this might be better than measuring real sounds is that the waveforms for sound are necessarily going to be more complex and, to get the maximum gross movement to match my "single wave" method in a sound pulse, the energy of my single wave would have to be the highest energy in a waveform that rose from zero energy a rapid to/fro sequence with a net energy near zero. As previously noted, I am not a physics guru and the two books that I would resort to in hopes of getting further inspiration are in storage. If you have access to a copy of _The Way Things Work_, there is almost certainly at least two designs that would meet your needs, and the things in TWTW are always concrete, they've-been-built-and-tested-in-non-laboratory conditions. Another good general reference to check for ideas on this stuff is Van Nostrand's Scientific Encyclopedia, and if you have the option, look first for a copy that is pre-'85. They stopped using English around then. -- The UN, the CDC and the WHO all say in blunt, unequivocal terms, "A flu pandemic is inevitable." Maybe not to your town and maybe not this year; but history shows us to expect three per century. The important hallmarks have already appeared this summer. Get a disaster kit. Twenty-first century cultures are highly mobile and Avian/Swine/Human flu hybrids kill even young, healthy people. Get masks, gloves, no-cook food for 3 days, and easily prepared food for 3 weeks. Do it today. The worst that can happen is you end up with spare groceries. The life you save will be someone you kiss, someone you hug, or someone you see every day. (If your life is so bad you hate all the people you see every day, then pray for plague.) ``` Previous message: [DPRG] Measuring Speed of sound in a liquid Next message: [DPRG] Measuring Speed of sound in a liquid Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list