John,
I think about these things:
Your omission of the reasonable logic which undermines your suppositions.
Your denial (through lack of acknowledgment) of things you clearly have written in this thread and later contradict.
Your avoidance of conventional wisdom for the sake of continuing a discussion based on things you post but cannot support.
I've thought about it. I find no support for your claims. You have provided none. You make a mockery of logic, thought and conventional wisdom upon which productive debate can be based.
We aren't playing from the same sheet of music, why would we change the beat?
From that I conclude there is no reason to continue.
I think about these things:
Your omission of the reasonable logic which undermines your suppositions.
Your denial (through lack of acknowledgment) of things you clearly have written in this thread and later contradict.
Your avoidance of conventional wisdom for the sake of continuing a discussion based on things you post but cannot support.
I've thought about it. I find no support for your claims. You have provided none. You make a mockery of logic, thought and conventional wisdom upon which productive debate can be based.
We aren't playing from the same sheet of music, why would we change the beat?
From that I conclude there is no reason to continue.
Ed LaFontaine said:
Sound is what we hear and for the majority of example it travels through air before we hear it. It's no big deal to compress air.
Through this all, no one has come forth with any document, website, or text that says definitively that sound waves actually compress water. Not one.
Show me where it is written, without reference to "particle theory", that water is indeed compressed by the passage of sound energy through it.
Wow, this is still going on?!!
I seem to recall several, and I'd guess there have been more since I exited the premisis, but just for grins, here's one more: http://smub.st-andrews.ac.uk/seismic/pdfs/3.pdf
Oops, I didn't see that qualifier. I guess we have to throw out the atomic theory of matter too, atoms being particles and all. But wait; haven't you used the term atom in this discussion?
And regarding "passage of sound energy": You don't by any chance mean waves do you? Or is that concept also in question now?
You have taken denial to new heights. Where were you when Bill Clinton could have used some help? Politicians around the globe would sell their souls (if they still had them) to have a fraction of your contortionist skills and perseverance in defending a position in the presence of overwhelming evidence to the contrary.
Somewhat off topic: I've seen positions taken in many different arenas that appear at the outset rational, based on the some given (and presumably testable) assumption. Irrationality becomes clear when the discussion gets down to numbers and measures. The scientific process requires putting hypothesis to the test, which invariably means measurements. The refusal to commit to verifiable and repeatable numbers and measures exposes the difference between a position based on rational inquiry and one based on belief alone.
Sheldon
MJL21193 said:
I seem to recall several, and I'd guess there have been more since I exited the premisis, but just for grins, here's one more: http://smub.st-andrews.ac.uk/seismic/pdfs/3.pdf
MJL21193 said:
Oops, I didn't see that qualifier. I guess we have to throw out the atomic theory of matter too, atoms being particles and all. But wait; haven't you used the term atom in this discussion?
And regarding "passage of sound energy": You don't by any chance mean waves do you? Or is that concept also in question now?
You have taken denial to new heights. Where were you when Bill Clinton could have used some help? Politicians around the globe would sell their souls (if they still had them) to have a fraction of your contortionist skills and perseverance in defending a position in the presence of overwhelming evidence to the contrary.
Somewhat off topic: I've seen positions taken in many different arenas that appear at the outset rational, based on the some given (and presumably testable) assumption. Irrationality becomes clear when the discussion gets down to numbers and measures. The scientific process requires putting hypothesis to the test, which invariably means measurements. The refusal to commit to verifiable and repeatable numbers and measures exposes the difference between a position based on rational inquiry and one based on belief alone.
Sheldon
MJL21193 said:
Um, yeah. I did note those passages. That's why I cited it.
"Compressional waves","pressure fluxuations", "at the location where particles are shown close together, one will find the maximum pressure of the sound wave".
What is it that is not clear about this referring to the compression of water as the mode of sound wave transmission? You may not want to believe what the author says, but you want to dispute the meaning of common words?
"Depends on what "is" means."
Are we present in the same universe? Can the meaning of words change anytime and for any purpose you want them to?
Sheldon
The "nonsense" that Auplater refers to, is not the passage from Munson, et. al.. Everything stated there is correct. It states there in unequivocal terms the compressibility of water, and provides the values necessary to compute it. Then it says that "liquids can be considered incompressible..." Wait, both can't be correct can they? Well, John, read on. "...for most practical engineering applications". For "most" practical engineering applications, i.e., ordinary (low precision) hydraulic systems one can ignore the small amount of compression that occurs.
Well, "most", and "in all cases" are not the same thing. Assuming that they are equivalent is what is nonsense. In the case of sound transmission in water, the compressibility cannot be ignored. In fact, in precision hydraulics it can't be ignored either. A compression of 1% at 3000 psi means a positional error of at least 1%, depending on the leverage ratio of the actuator. You can ignore that on your skip loader - you'd best not do it on your rocket ship.
Sheld0n
Well, "most", and "in all cases" are not the same thing. Assuming that they are equivalent is what is nonsense. In the case of sound transmission in water, the compressibility cannot be ignored. In fact, in precision hydraulics it can't be ignored either. A compression of 1% at 3000 psi means a positional error of at least 1%, depending on the leverage ratio of the actuator. You can ignore that on your skip loader - you'd best not do it on your rocket ship.
Sheld0n
Sheldon said:
It says "pressure" not "compression" and in reference to the "particle theory" model, the particles are "shown" close together. I have said that as sound moves through water it forms regions of high and low pressure. Once again, pressure is not the same as compression.
I asked for a black and white, it is written this way, reference that says: "sound waves compress water" as the primary means of sound propagation through the medium.
Sheldon said:
Well, I'm not going to take auplater's comment to heart - he did say stress is a force, after all.
His contribution here is an irritant at best.
Did you skip over the part where it's written that it takes "a large pressure change to create a small change in volume"? Where is this large pressure coming from? How can you stand by the idea that the primary means for sound energy travel through water is by compression? Sound energy transfer through water is by displacement - this takes very little energy. This is logic, for God's sake!
MJL21193 said:
You can't have adjacent regions of high and low pressure without compression.
As regards black and white; you've been given citations that say, if not exactly that, then the logical equivalent. If you don't understand how to make simple extensions of logical statements, then it's hopeless.
MJL21193 said:
Nope, I didn't skip it. "Large" and "small" are meaningless terms out of context. Things are only large or small relative to other things. The amount of compression, as a percentage of starting volume, is much less than 1% for typical sound waves propagated in water, so the amount of force required is much less than 3000 psi. So? No one has claimed otherwise. Does this mean you are ready to talk numbers?
Sheldon
compresion of H20
MJL21193, what are we really trying to explain, does water compress? Do sound waves compress water as they propagate?
Part of me thinks I understand your logic, correct me if i am wrong, you believe that there is no compression of water via sound due to the lack of overall density increase/ decrease?
FACT 1000Kg per square centimeter water compresses by 2.5% at 50 degree C, therefor if you apply a sound wave of 1000Kg per square centimeter of force you will compress water by 2.5% or am I missing something???
H2O behaves in a very unique fashion, by 4 degrees C water molecules energy has dropped enough that they are very close to one another, so each H2O molecule forms a stable hydrogen bond with up to four fellow molecules at 0 degrees C, forming an open hexagonal shape they are held rigidly apart, hence why water expands when frozen, but at tempratures above freezing water behaves normally.
The same known laws of physics apply to water as any other compound, element ect.
I think you are confusing pressure waves in fluid dynamics with compression even when they both amount to the same thing. Sound will create pressure waves in water period.........
MJL21193, what are we really trying to explain, does water compress? Do sound waves compress water as they propagate?
Part of me thinks I understand your logic, correct me if i am wrong, you believe that there is no compression of water via sound due to the lack of overall density increase/ decrease?
FACT 1000Kg per square centimeter water compresses by 2.5% at 50 degree C, therefor if you apply a sound wave of 1000Kg per square centimeter of force you will compress water by 2.5% or am I missing something???
H2O behaves in a very unique fashion, by 4 degrees C water molecules energy has dropped enough that they are very close to one another, so each H2O molecule forms a stable hydrogen bond with up to four fellow molecules at 0 degrees C, forming an open hexagonal shape they are held rigidly apart, hence why water expands when frozen, but at tempratures above freezing water behaves normally.
The same known laws of physics apply to water as any other compound, element ect.
I think you are confusing pressure waves in fluid dynamics with compression even when they both amount to the same thing. Sound will create pressure waves in water period.........
Re: compresion of H20
Who says?
Look at it this way, to put it in relative terms: You drive your car into the ditch while daydreaming about this subject. A couple of strong men stop and push your POS car out of the ditch and back on the road. You drive off, without a word of thanks, because you are angry about the small dent one of the helpful gentlemen put in your trunk lid while pushing your car back to usability.
Look at the small detail, blind to the full picture.
What you and everyone else seems to be missing is that in order to compress something, it can't be free to move. You can apply 1000000000000Kg per square centimeter and all it will do is push it away. To compress, the medium must be constrained or the compressing force needs to be exerted from all directions.
Try to crush a pop can against air - it will not happen, because the pop can is free to move. Crush that same can against the floor with your foot and you will be successful.
I'll correct you on your assumption that I meant overall compression - I didn't. There is no local compression either.
Overall, density will decrease (I've only said that about 10000 times) Whenever you introduce energy, work is done and heat is produced and the medium expands in volume.
BTW, good luck getting that kind of pressure from a sound wave. Typical measure in the micro Pascal range.
Sheldon said:
Who says?
Sheldon said:
Look at it this way, to put it in relative terms: You drive your car into the ditch while daydreaming about this subject. A couple of strong men stop and push your POS car out of the ditch and back on the road. You drive off, without a word of thanks, because you are angry about the small dent one of the helpful gentlemen put in your trunk lid while pushing your car back to usability.
Look at the small detail, blind to the full picture.
tiltedhalo said:
What you and everyone else seems to be missing is that in order to compress something, it can't be free to move. You can apply 1000000000000Kg per square centimeter and all it will do is push it away. To compress, the medium must be constrained or the compressing force needs to be exerted from all directions.
Try to crush a pop can against air - it will not happen, because the pop can is free to move. Crush that same can against the floor with your foot and you will be successful.
I'll correct you on your assumption that I meant overall compression - I didn't. There is no local compression either.
Overall, density will decrease (I've only said that about 10000 times) Whenever you introduce energy, work is done and heat is produced and the medium expands in volume.
BTW, good luck getting that kind of pressure from a sound wave. Typical measure in the micro Pascal range.
H20
For realistic purposes you apply sound waves to water they propagate creating high and low points of pressure what some people are calling "compression", but that does not change the overall volume of water it is neither a state change or actual compression, just pressure waves that will travel to the end of the conducting media i.e. water. Apply those sound waves to an enclosed media and apply enough sound energy you can compress H20, but that's allot of sound energy.
Does an underwater earthquake compress the surrounding water? No the energy travels to the end of the conducting media in pressure waves of high static to low static energy but do not compress anything.
For realistic purposes you apply sound waves to water they propagate creating high and low points of pressure what some people are calling "compression", but that does not change the overall volume of water it is neither a state change or actual compression, just pressure waves that will travel to the end of the conducting media i.e. water. Apply those sound waves to an enclosed media and apply enough sound energy you can compress H20, but that's allot of sound energy.
Does an underwater earthquake compress the surrounding water? No the energy travels to the end of the conducting media in pressure waves of high static to low static energy but do not compress anything.
Any mention of volume change is a red herring, this has nothing to do with making a volume of water smaller or larger or how much sound energy that would take. All you seem to be arguing now is that your "pressure wave" shouldn't be called a compression wave by everyone in the world. You are not in control of the english language, like it or not this is what it is called. Nobody has ever claimed sound is going to make a bathtub full of water less full yet you keep trying to use that obviously illogical idea as "proof" that a water molecule never moves closer to it's neighbors.
Your theory predicts that sound would not be able to propagate through water that was enclosed in an infinitely stiff container and conveniently this is untestable because such a thing does not exist, but the speed of sound in water can be measured and your model can not account for it. If a water molecule didn't spend time traveling over closer to it's neighbor before bumping it and transferring it's energy then the speed of sound would be infinite. This has always been fatal to your theory but you pretend it's not by some hand waving about "loss of transfer efficiency". Explain the mechanism that accounts for the speed of sound in water in your model and how to calculate that speed.
Your theory predicts that sound would not be able to propagate through water that was enclosed in an infinitely stiff container and conveniently this is untestable because such a thing does not exist, but the speed of sound in water can be measured and your model can not account for it. If a water molecule didn't spend time traveling over closer to it's neighbor before bumping it and transferring it's energy then the speed of sound would be infinite. This has always been fatal to your theory but you pretend it's not by some hand waving about "loss of transfer efficiency". Explain the mechanism that accounts for the speed of sound in water in your model and how to calculate that speed.
poptart said:
Elasticity. Water lacks it.
I have explained this before. You just read what you want a disregard the rest.
Water doesn't have a neat crystalline structure like metal, where the molecules are all the same size and in line with each other. The energy transfer will not be directly to a neighboring molecule, but could be to 2 or more "glancing blows". (picture a cue ball hitting another ball at an angle - both balls are redirected).
Due to waters low elasticity, the molecules, once moved, may not return to their original place. These conditions reduce the transfer efficiency through the medium, thereby reducing the speed that sound can travel through the medium.
I made an analogy dealing with this with a layer of sand on a table top as an example above, but I guess you skipped that too.
Hello again John, good to see you have some well deserved free time. You asked for a reference which describes the method of sound propagation in a fluid (specifically water).
I reference the text Fundamentals of Acoustics by Kinsler, Frey, Coppens, and Sanders. From page one of the Fourth Edition:
From Chapter 5.1, pg. 113:
s = (p-po)/po
where;
p = instantaneous density at (x, y, z)
p[I/] = equilibrium density at (x, y, z)
s = condensation at (x, y, z)
The existence of this equation implies that yes; a small change in fluid density is required as the fluid is compressed during the pressure wave propagation.
The text explains further on pg. 114:
The word "displaced" will no doubt catch your attention. It is exactly this word which lets me know that intuitively you are on the right track. Displacement is necessary to produce sound waves. On that I think we agree. But displacement alone is not enough to explain acoustic propagation of non-infinite velocities. The thought exercises I previously proposed explained [hopefully] why there must be some finite time of propagation. This propagation of the initial displacement occurs in the form of traveling pressure waves, each wave pushing and pulling the adjacent molecules to propagate the wave through the medium.
To summarize:
A displacement (oscillating in the case of acoustic sources) causes a compression or rarefaction of adjacent fluid molecules. This compression or rarefaction (local change in fluid density) results in a local increase or decrease in pressure, which expands to or contracts inward from the adjacent fluid (which is at a lower or higher equilibrium pressure). The elastic nature (at the molecular force level) of the compressible fluid provides the restoring force of the fluid back towards equilibrium.
And yes it is possible to have longitudinal vibrations (compression waves) in a solid metal bar, that's chapter 3 in the book.
Best Regards,
David Malphurs
I reference the text Fundamentals of Acoustics by Kinsler, Frey, Coppens, and Sanders. From page one of the Fourth Edition:
From Chapter 5.1, pg. 113:
At this point in the text there are some equations listed which define the equilibrium position, particle displacement, particle velocity, condensation (or compression), and acoustic pressure of a region of particles. Of particular interest is the equation for condensation (compression) of the fluid, which is defined as:
s = (p-po)/po
where;
p = instantaneous density at (x, y, z)
p[I/] = equilibrium density at (x, y, z)
s = condensation at (x, y, z)
The existence of this equation implies that yes; a small change in fluid density is required as the fluid is compressed during the pressure wave propagation.
The text explains further on pg. 114:
The word "displaced" will no doubt catch your attention. It is exactly this word which lets me know that intuitively you are on the right track. Displacement is necessary to produce sound waves. On that I think we agree. But displacement alone is not enough to explain acoustic propagation of non-infinite velocities. The thought exercises I previously proposed explained [hopefully] why there must be some finite time of propagation. This propagation of the initial displacement occurs in the form of traveling pressure waves, each wave pushing and pulling the adjacent molecules to propagate the wave through the medium.
To summarize:
A displacement (oscillating in the case of acoustic sources) causes a compression or rarefaction of adjacent fluid molecules. This compression or rarefaction (local change in fluid density) results in a local increase or decrease in pressure, which expands to or contracts inward from the adjacent fluid (which is at a lower or higher equilibrium pressure). The elastic nature (at the molecular force level) of the compressible fluid provides the restoring force of the fluid back towards equilibrium.
And yes it is possible to have longitudinal vibrations (compression waves) in a solid metal bar, that's chapter 3 in the book.
Best Regards,
David Malphurs
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