Compression of water (split from Waveguides) - Page 5 - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th July 2008, 05:34 PM   #41
Daveze is offline Daveze  Australia
diyAudio Member
 
Join Date: Jun 2004
Location: Sunny Queensland, Australia
Quote:
Originally posted by MJL21193

I think not. Molecular movement will decrease density.
You're only looking at one side of the motion. Its action/re-action...in action. If I have A|||B|||C, then introduce an action such that /A||B|||C occurs, I have locally increased the density of A and B (not affecting C). However A and B would rather be ||| apart, so this occurs next: /A|||B||C (because B has some inertia). But B and C want to be ||| apart, so it becomes: /A|||B|||C and everybody has moved forward by '/'. It is the speed that the || becomes ||| that dictates how quickly speed will move through the substance.

Quote:
Originally posted by MJL21193
Feel the heat from your refrigerators compressor and condenser lately?
But when was your last cold beer, milk, ice cube...Its about where you observe and what you relate your observation to.

Quote:
Originally posted by MJL21193
Depending on temperature, molecules are always in motion. As temperature goes up, density goes down, as does the speed which sound will move through it.
Waitaminute, which way did speed go? Up or down, your statement is ambiguous.

To comment anyway: You should see the speed go down, not strictly because density went down but because compressibility increases with temperature. Increased compressibility translates to a reduced desire to resist a change and consequently slow the propagation of the pressure wave.
__________________
Signature Pending...
  Reply With Quote
Old 25th July 2008, 05:35 PM   #42
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by Daveze

Experiment: Take a beer bottle. Consume beer. Refill with water to the brim. Hold filled bottle by neck. Take palm. Slap top of bottle in forceful manner. Watch your feet. Seek medical attention if required. Review your super high speed camera and observe the time that it takes between the slapping and the shattering. That time is the speed that the pressure wave propagates through the fluid. That speed is the speed of sound in water.
But this only proves my point - simple hydraulics, transfer of energy from the bigger piston (the bottles end) and the smaller piston (the cap). Mechanical advantage, that's what hydraulics are about. Using the relative incompressibility of a fluid.
When you fill something completely with water, for sound transmission purposes, it behaves like a solid. The container that holds the water and the water inside will conduct sound - no compression. Just like a solid hunk of steel.
  Reply With Quote
Old 25th July 2008, 05:37 PM   #43
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by MJL21193
....Water expands below freezing, not above it.....
no, water expands either side of 4degC.
Ice contracts as the temperature is lowered.

It's this expansion below 4degC that allows the aquatic life to survive.
A clever trick of nature that enabled colonisation of the Earth.
__________________
regards Andrew T.
  Reply With Quote
Old 25th July 2008, 05:41 PM   #44
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by AndrewT
no, water expands either side of 4degC.
Ice contacts as the temperature is lowered.

Yes Andrew, you are correct. I was not as sharp on that detail. Thanks.
Still, at 4*C what do we see, as far as molecular movement is concerned? Less movement or more?
  Reply With Quote
Old 25th July 2008, 05:43 PM   #45
Daveze is offline Daveze  Australia
diyAudio Member
 
Join Date: Jun 2004
Location: Sunny Queensland, Australia
Quote:
Originally posted by MJL21193

But this only proves my point - simple hydraulics, transfer of energy from the bigger piston (the bottles end) and the smaller piston (the cap). Mechanical advantage, that's what hydraulics are about. Using the relative incompressibility of a fluid.
When you fill something completely with water, for sound transmission purposes, it behaves like a solid. The container that holds the water and the water inside will conduct sound - no compression. Just like a solid hunk of steel.
But it doesn't. Even solids don't act as solids. It will take a finite period of time for the bottle to break at the bottom after you break it at the top. Even a photon will take a finite period of time to travel the distance from the top of the bottle to the bottom. To say that the liquid is completely incompressible, and will hence translate the force instantaneously, is in defiance of Einstein's Theory of Special Relativity.
__________________
Signature Pending...
  Reply With Quote
Old 25th July 2008, 05:43 PM   #46
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by Daveze





But when was your last cold beer

This morning...
  Reply With Quote
Old 25th July 2008, 05:43 PM   #47
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Actually water is a very naughty substance, it expands both below 4șC and above 4șC having a maximum density point at that temperature. It's not a linear medium, it's likely to distort sound (like air but worse).

If you want to read on water anormalities (I strongly recommend you to read this):
http://www.lsbu.ac.uk/water/explan2.html

Anyway, since you have agreed that water volume changes with themperature (across the liquid phase), you have already agreed that water may be compressed and expanded (by changing temperature).

Indeed, when sound propagates through water, the resulting compressed and the expanded zones are likely to have different temperatures (as it happens with air).
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 25th July 2008, 05:49 PM   #48
Daveze is offline Daveze  Australia
diyAudio Member
 
Join Date: Jun 2004
Location: Sunny Queensland, Australia
Quote:
Originally posted by Eva
Actually water is a very naughty substance, it expands both below 4șC and above 4șC having a maximum density point at that temperature. It's not a linear medium, it's likely to distort sound (like air but worse).
Naughty naughty water. I think a substance has been misbehaving, needs to be given a thorough spanking and should think about what its done wrong...
__________________
Signature Pending...
  Reply With Quote
Old 25th July 2008, 05:54 PM   #49
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by Daveze

is in defiance of Einstein's Theory of Special Relativity.
Invoking Einstein, eh?

Quote:
Originally posted by Eva

Anyway, since you have agreed that water volume changes with themperature (across the liquid phase), you have already agreed that water may be compressed and expanded (by changing temperature).

What is waters natural state? Liquid, is it not? Water that has been heated to the boiling point does not compress back to water, it condenses. To do this it's temperature needs to drop. Not outside force is needed, therefore no compression.

More grade school oversimplification, I'm sure.
  Reply With Quote
Old 25th July 2008, 06:01 PM   #50
MartinQ is offline MartinQ  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Ontario, Canada
Quote:
Originally posted by MJL21193
What is waters natural state? Liquid, is it not?
That depends entirely on it's environment.

Quote:
Originally posted by MJL21193
Water that has been heated to the boiling point does not compress back to water, it condenses. To do this it's temperature needs to drop. Not outside force is needed, therefore no compression.
Compressing a substance increases its temperature (adding energy), and thus cooling a substance can lead to contraction (removing energy). So you can compress a substance by cooling.

Quote:
Originally posted by MJL21193
More grade school oversimplification, I'm sure.
Your favorite, cozy cozy world. It helps you feel safe.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 12:21 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2