- #36
erickalle
- 83
- 0
Astronuc said:The KE of the gas molecules affects the pressure, not the speed of sound.
For an ideal gas: KE=1/2mv^2=3/2kT.A more accurate expression is
c = \sqrt {\kappa \cdot R\cdot T}
where
* R (287.05 J/(kg·K) for air) is the universal gas constant (In this case, the gas constant R, which normally has units of J/(mol·K), is divided by the molar mass of air, as is common practice in aerodynamics)
* κ (kappa) is the adiabatic index (1.402 for air), sometimes noted γ
* T is the absolute temperature in kelvins.
In fact, assuming an ideal gas, the speed of sound c depends on temperature only, not on the pressure. Air is almost an ideal gas. The temperature of the air varies with altitude, giving the following variations in the speed of sound using the standard atmosphere - actual conditions may vary.
I am not going to change my view wrt gasses but I still have to have a long hard look at metals. In the mean time if anybody has some more info I'd be greatfull.
eric