Re: Fastest living thing

On Nov 17, 4:47 pm, "Mike Painter" <mddotpain...@xxxxxxxxxxxxx> wrote:
rnorman wrote:
On Nov 17, 12:50 pm, "Mike Painter" <mddotpain...@xxxxxxxxxxxxx>
wrote:

Ignoramus. No one uses mach numbers for pollen, except cretinists,
who
literally don't know any better.

The speed of sound is
1,116.4 ft/s
340.3 m/s
761.2 mph
1,225.1 km/h
661.5 knots

I'm going to guess that you looked this up someplace and either the
site didn't mention it or you didn't read the rest.
The part that talks about teh density of the air changing the speed.

It is actually temperature that is the critical variable.  Of course
density varies with temperature.  Composition also is important:
moist air is different from dry air.

It's both temperature and pressure. If temperature was the critical factor
then as things got colder sound would travel faster.
However at 50,000 feet it's real cold and sound is s   l   o   w   e  r.


It is sort of complicated and all this goes back a half century for me
but reviewing Wikipedia
http://en.wikipedia.org/wiki/Speed_of_sound
confirms that the speed of sound in an ideal gas depends only on
temperature and molecular weight
c = sqrt(gamma * RT/M)
where gamma is the adiabatic constant, 1.4 for diatomic gases, M the
molecular weight, and RT the usual.

The efffect of density is offset by the effect of bulk modulus
(elasticity). In any event, that formula indicates that cold gas
conducts at a lower velocity than warm gas. Moisture is important by
changing the molecular components, both the average molecular weight
and, to a slight degree, the average adiabatic constant.


.

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