| Topic: |
Science > Physics |
| User: |
"Florian" |
| Date: |
07 Apr 2007 05:06:12 PM |
| Object: |
Behaviour of a wave in a fluid |
Hi,
I'm not a physicist, and I need some clues from specialists about the
behaviour of waves in a fluid.
What does happen to the maximal velocity of a wave when the density of
the fluid decreases? Does it increase?
If a wave travels in a fluid which density decreases with time, what
does happen to the frequency of the wave? Does it decrease?
Thank you.
--
Florian
"Tout est au mieux dans le meilleur des mondes possibles"
Voltaire vs Leibniz (1-0)
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| User: "Androcles" |
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| Title: Re: Behaviour of a wave in a fluid |
07 Apr 2007 07:12:24 PM |
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"Florian" <firstname@lastname.net> wrote in message =
news:1hw84b0.1qylgoaudjx96N%firstname@lastname.net...
=20
Hi,
=20
I'm not a physicist, and I need some clues from specialists about the
behaviour of waves in a fluid.
=20
What does happen to the maximal velocity of a wave when the density of
the fluid decreases? Does it increase?
http://www.sengpielaudio.com/calculator-speedsound.htm
If a wave travels in a fluid which density decreases with time, what
does happen to the frequency of the wave? Does it decrease?
=20
Thank you.
That question is not a simple one to answer, since it depends=20
on the frame of reference in which the frequency is measured.
Obviously there is no change in frequency at the source,
but as this demonstration clearly shows when the relative velocity
of a wave changes so does the apparent frequency and wavelength.
http://www.androcles01.pwp.blueyonder.co.uk/AC/doppler.gif
http://www.androcles01.pwp.blueyonder.co.uk/AC/doppler2.gif
The orange dumbell sees twice the frequency and half the wavelength,
giving the incorrect assumption that the speed is c =3D 1/2*lambda * =
2*nu =3D1
when it is in fact 2c =3D 1/2 * lambda * nu.
The purple dumbell travels with the wave and has a frequency of zero
and an undefined wavelength ( the distance to the next crest can be=20
anything).=20
That result will trip up many an amateur who attempts to measure
wavelength with a diffraction grating without using the correct (source) =
frequency. A shorter wavelength means a higher velocity.
If the crests come at you twice as fast the wave is travelling twice as=20
fast. There are a number of amateurs contributing to this newsgroup=20
who do not (and never will) understand that.
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| User: "Uncle Al" |
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| Title: Re: Behaviour of a wave in a fluid |
07 Apr 2007 07:26:25 PM |
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Florian wrote:
Hi,
I'm not a physicist, and I need some clues from specialists about the
behaviour of waves in a fluid.
What does happen to the maximal velocity of a wave when the density of
the fluid decreases? Does it increase?
If a wave travels in a fluid which density decreases with time, what
does happen to the frequency of the wave? Does it decrease?
Thank you.
http://www.pha.jhu.edu/~broholm/l28/node4.html
http://en.wikipedia.org/wiki/Acoustic_wave_equation
<http://sepwww.stanford.edu/sep/prof/bei/fdm/paper_html/node40.html>
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16196738&dopt=Abstract>
For the masochist
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
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| User: "Androcles" |
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| Title: Re: Behaviour of a wave in a fluid |
07 Apr 2007 07:38:59 PM |
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"Uncle Al" <UncleAl0@hate.spam.net> wrote in message =
news:461836B1.135315FC@hate.spam.net...
[snip river of *****]
beta cannot be derived, dumbfuck. You are the stooopidest *****=20
since Dork Van de psychopath hit a keyboard.
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| User: "Bruce Scott TOK" |
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| Title: Re: Behaviour of a wave in a fluid |
10 Apr 2007 12:21:00 PM |
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Florian wrote:
|> I'm not a physicist, and I need some clues from specialists about the
|> behaviour of waves in a fluid.
|>
|> What does happen to the maximal velocity of a wave when the density of
|> the fluid decreases? Does it increase?
Do you mean sound waves or surface waves? These are different,
representing compressional and shearing motions of the fluid,
respectively.
--
ciao,
Bruce
drift wave turbulence: http://www.rzg.mpg.de/~bds/
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