Re: [Phys-l] speed of sound

[John Denker <jsd@av8n.com>]

On 04/16/2007 02:27 PM, Anthony Lapinski wrote:

> Can someone guide me to a web site or a formula for the speed of sound in
> CO2 from 0 °C to 100 °C? 

The formula is pretty widely known.  See e.g. Feynman volume I
chapter 47 ... in particular, equation 47.24 ... or you could
just rederive it from scratch.

Knowing the physics is useful, because looking up the gamma
is easier than looking up the speed of sound per se.

You can rederive most of the formula in your head, just using
dimensional analysis.  All you really need to remember is whether
there is a factor of gamma in there (which there is).



You can get gamma as a function of temperature from
  http://www.cstl.nist.gov/div836/836.01/PDFs/2004/Gas_Properties.pdf
plus a few minutes of spreadsheet work.



If I were doing it, I would do /air/ first, and check that the NIST
polynomial reproduces known results such as are found at
  http://www.engineeringtoolbox.com/dry-air-properties-d_973.html
... and then move to co2.  I like to check my work.