I did not leave, I have been reading this diatribe and as a result have wasted dozens of hours getting involved in trying to understand your viewpoint and trying to help extract the truth.
But, you come back with ridiculous statements that you have not bothered to research carefully because the premise does not fit your interpretation of the world. Ostriches come to mind.
But, you come back with ridiculous statements that you have not bothered to research carefully because the premise does not fit your interpretation of the world. Ostriches come to mind.
despotic931 said:
But don't you see what you are saying? What determines the temperature of an object? How much the molecules are moving. It is the heat produced by the friction of the molecules moving that determines its temperature. Every object has moving molecules (above absolute zero). These molecules are converting energy to heat. Where does the energy come from? The surrounding environment, an outside source. Take away the energy source and eventually the molecules will stop moving as they use up the remaining energy.
What determines the volume an unconstrained object will occupy? Temperature and the surrounding pressure. Change the temperature while maintaining the pressure equates to a volume change.
When you use energy to increase molecules motion this directly results in a volume change. It is not a "byproduct" but a direct result.
There has been constant denial of the importance (and even the existence by a couple of well respected members) of this. It is more relevant than compression.
BTW, quoting my original post is fine. The context is missing as this thread originated elsewhere.
I have come to some more specific conclusion since then and I have Incorporated them into the mix. The end result is still the same: the primary mechanism for sound transfer through a medium is displacement, not compression.
SY said:
That figures.
I am left to find my way to the correct understanding without your help.
AndrewT said:
Andrew, I have said a couple of things that are blatantly false but not everything I have written here is a "ridiculous statement".
I challenge you to be specific. You can start here:
I have said compression does happen but it is not the primary mechanism for sound transmission through a medium. I say it is displacement (as in the volume of the medium expands to accommodate this added motion.)
I liken this to moving an object in the physical world where the force exerted overcomes inertia and friction to reposition the object. If the object were to be dented (compression) slightly at the point where the force is brought to bear, this is but a tiny part of the bigger picture; the bigger picture being that the object has been moved.
SY said:
Really? Read here .
I'll quote for those who can't be bothered to click the link:
" Heat, Temperature, and the Particle Theory
What actually is the difference between water at 20ºC and water at 50ºC? What is the difference between heat and temperature? How are these questions related? Can any one hypothesis answer both questions?
The Particle Theory
Scientists now use the kinetic molecular theory, or particle theory, to explain heat and temperature and the difference between, say, 20ºC and 50ºC. The particle theory is based on a model that suggests that all matter is made up of tiny particles too small to be seen. According to this model, these particles are always moving- they have energy. The more energy they have, the faster they move. So far, all the evidence is made up of moving particles. That is why we call the particle model for matter a theory.
Heat and Temperature
So what is the difference between heat and temperature? According to the particle theory, heat is energy, and it is transferred from hotter substances to colder ones. Temperature is a measure of the average energy level of the particles in a substance.
Both hot and cold water are made up of moving particles, some moving quickly, and some moving slowly. But on average, the particles move faster in hot water than in cold water.
Expanding and Contracting
The particle theory is a useful model to explain why substances expand when they are heated and contract when they are cooled. At high temperatures, particles have more energy, move more quickly, and have more collisions. As a result, they take up more space, and the substance expands. At lower temperatures, particles have less energy, move more slowly, and have fewer collisions. They take up less space, and the substance contracts."
SY said:
Now, who is demonstrating lack of basic understanding?
The quoted reference was gibberish too? It's right there in plain English for anyone to read and it completely agrees with what I said in my post.
If this as helpful as you can be, keep it. I'll suffer in my "ignorance" rather than subscribe to your view of the world.
Ooops....
As water warms, it expands.*
* This is not true for water between 32° F and 39.2° F.
Ok so by the new theory sound will not propagate at these temperatures, or will it propagate losslessly, or backwards, or what??
Edit, I think there's a critical temperature (easily producible in the home) where you would have "rectification" as the sound wave passes.
As water warms, it expands.*
* This is not true for water between 32° F and 39.2° F.
Ok so by the new theory sound will not propagate at these temperatures, or will it propagate losslessly, or backwards, or what??
Edit, I think there's a critical temperature (easily producible in the home) where you would have "rectification" as the sound wave passes.
gtforme00 said:
Yes.
scott wurcer said:
As water freezes, it aligns it's molecules in a crystalline structure (similar to metal). This reduces density (that's why water expands while freezing). With this deduction in density, the "room" for movement already exists in the medium. Ice is almost 10% less dense than water.
Yeah, I know you thought this was a Eureka! moment. Sorry to burst that bubble.
John, it might help to read an actual textbook and work problems; this will help you to understand when what you're reading is applicable. General low-level educational sites like that are fine for high school kids doing a homework assignment, but you're trying to get in deeper than that.
Scott gave you an excellent specialized reference. At a more introductory level, kinetic theory is well-explained in old standbys like Halliday and Resnick and at a more profound and interesting level in the Feynman Lectures (vol 1). French's Vibrations and Waves will clear up your fundamental non-understanding of basic wave theory and the meaning of simple terms like displacement and compressional waves.
Specific application to understanding density (and compression) fluctuations in water is well treated in Kinsler's Fundamentals of Acoustics. What you seek can be pulled out of chapter 5. I gave a qualitative explanation quite a few pages back, but there's nothing like going through it yourself with some rigor.
Scott gave you an excellent specialized reference. At a more introductory level, kinetic theory is well-explained in old standbys like Halliday and Resnick and at a more profound and interesting level in the Feynman Lectures (vol 1). French's Vibrations and Waves will clear up your fundamental non-understanding of basic wave theory and the meaning of simple terms like displacement and compressional waves.
Specific application to understanding density (and compression) fluctuations in water is well treated in Kinsler's Fundamentals of Acoustics. What you seek can be pulled out of chapter 5. I gave a qualitative explanation quite a few pages back, but there's nothing like going through it yourself with some rigor.
MJL21193 said:
What is the purpose of this comment? It's only likely to inspire anger, and I believe that that is its intent.
How disappointing for you in that case.
This is a mere insult. If you believe it to be true it displays a serious lack of imagination on your part.
I'm not unhappy to see it, however, as it betrays the fact that you yourself do not have confidence in your own argument.
As I said before, blood in the water.
You're holed below the waterline.
w
Drip, drip, drip.
Interesting point Scott. A side note is that not only does water not propagate losslessly at those temperatures, it actually exceeds the losses that the classical absorption model predicts. The explanation of this is beyond the scope of this discussion, but the keyword to search for is "structural relaxation".
There are three major ways in which energy is absorbed by the medium during acoustic propagation. I should first note that the energy absorbed by the water itself during acoustic propagation is very small. Most of the absorption is due to absorption from the bottom of the body of water or suspended objects in the water (life forms or entrained air).
The first (and in liquids the dominant) absorption method is absorption is from viscosity. This is basically the friction loss so often mentioned in this thread.
The second method is heat conduction loss. These losses are due to the conduction of thermal energy from the higher pressure (and higher temperature) part of the wave to the lower pressure part of the wave.
The third method is absorption from molecular processes. This includes changes in molecular structure, rotation, and ionization.
-David
There are three major ways in which energy is absorbed by the medium during acoustic propagation. I should first note that the energy absorbed by the water itself during acoustic propagation is very small. Most of the absorption is due to absorption from the bottom of the body of water or suspended objects in the water (life forms or entrained air).
The first (and in liquids the dominant) absorption method is absorption is from viscosity. This is basically the friction loss so often mentioned in this thread.
The second method is heat conduction loss. These losses are due to the conduction of thermal energy from the higher pressure (and higher temperature) part of the wave to the lower pressure part of the wave.
The third method is absorption from molecular processes. This includes changes in molecular structure, rotation, and ionization.
-David
underwater HT
So.. if I want to setup an underwater home theatre in my pool, what are some of the considerations I need to take into account?
Maybe a drysuit if I'm listening and watching between 32F and 39F and a more powerful amp, eh??
For summer months, since the water will be expanding beyond the bounds of the pool at high listening levels, maybe I need some splash guards so the "sound doesn't escape"..???
After all, it could make "Flipper" much more realistic than plain ole 1080p...
John L.
So.. if I want to setup an underwater home theatre in my pool, what are some of the considerations I need to take into account?
Maybe a drysuit if I'm listening and watching between 32F and 39F and a more powerful amp, eh??
For summer months, since the water will be expanding beyond the bounds of the pool at high listening levels, maybe I need some splash guards so the "sound doesn't escape"..???
After all, it could make "Flipper" much more realistic than plain ole 1080p...
John L.
Your words not mine...
Once again, how do you do work, transfer energy and dissipate energy without creating heat? Energy in = increased motion = friction = A change of temperature = volume change (displacement).
This is key - put on your thinking cap.
There is no volume change with temperature at 4C (water is still a liquid not "almost" ice BTW). So what parameter of sound in water is proportional to the change in density vs change in temperature? You can get off easy and not provide a complete mathematical framework just some simple proportionalities such as speed of propagation or attenuation vs distance. At 4C they either vanish or go to infinity. I think by your reasoning the zero change in density with temperature would actually make the attenuation increase exponentially as you approach 4C.
Easily verifiable even in your kitchen.
Once again, how do you do work, transfer energy and dissipate energy without creating heat? Energy in = increased motion = friction = A change of temperature = volume change (displacement).
This is key - put on your thinking cap.
There is no volume change with temperature at 4C (water is still a liquid not "almost" ice BTW). So what parameter of sound in water is proportional to the change in density vs change in temperature? You can get off easy and not provide a complete mathematical framework just some simple proportionalities such as speed of propagation or attenuation vs distance. At 4C they either vanish or go to infinity. I think by your reasoning the zero change in density with temperature would actually make the attenuation increase exponentially as you approach 4C.
Easily verifiable even in your kitchen.
"The temperature of water in the surface goes on decreasing to 0 degree C & finally is converted into ice, while the water below the ice continues to remain at 4 degree C. As water remains at 4 degree C, fish & other aquatic animals remain alive."
And presumably keep on singing to each other.
And presumably keep on singing to each other.
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