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**Molecular Speed vs. Sonic Speed**

First, this is my first post here. Second, I've been wrestling with these same questions over in the, Electrotech Forum. Third, I am a math moron so I need to think of these things conceptually rather than mathematically (throw equations at me and you may as well be speaking Swahili). Fourth, I think you are asking the right question: Trying to nail down how the molecules themselves are acting but, I think that rather than going to a more advanced forum, perhaps simplifying things might be more beneficial?Anybody knows any more advanced physics forums?

If the question is how fast the molecules of air are moving, here's a web page that may be of interest.

http://www.newton.dep.anl.gov/askasci/chem03/chem03448.htm

But, let me quote a passage of interest here:

"There's a really neat mathematical equation based on a theorem called

the "equipartition theorem" which states that the energy of a gas system

(equal to 1/2*mv^2) is equal to the temperature of the gas (equal to 3/2*kT).

If we rewrite this equation to solve for velocity we get:

sqrt(3*T*k/m) = v

where T is the temperature in Kelvin, k is the Boltzman constant = 1.3805*10^-

23 J/K and m is the mass of the gas particle.

If we assume that the average mass of air (since it is a mixture of different

gases) is 28.9 g/mol (or each gas particle is around 4.799*10^-26), and room-

temperature is 27C or 300K, we find that the average velocity of a single air

particle is around 500 m/s or 1100 miles per hour!"

The reaon I find this particularly interesting as it relates to the speed of sound is by thinking of what the average speed might be in a linear direction.

If an air disturbance is propelled by the collisions of the molecules and the molecules are moving at a nominal 1100 mph, some of the time the sound will be propagted at that speed. But, related to that selected direction, some will be at right angles to that direction and will propagate along that axis at zero mph. Other rates will depend on other angles and should average out to about the speed of propagation at 45 degrees.

That puts the average at about 770 mph along any given axis. To me that seems just a little too close to the nominal Mach 1, under standard conditions, of 761 mph to be a simple coincidence.