What is the density of air?

[huybinhs]

what is the density of air?

Homework Statement

For a gas at pressure P, the Bulk modulus B (under adiabatic conditions of change) is g · P. At a certain temperature, at normal atmospheric pressure, the velocity of sound in air is found to be 339.5 m/s. If g for air is 1.40, what is the density of air (in kg/m3) at that temperature ?

2. The attempt at a solution

Given wavelength, and v, then I found f:

f = v / wavelength = 242.5 Hz.

I know that:

B = v^2 * p

and B = wavelength * P

=> v^2 * p = wavelength * P

but how to find P?

I need it in couple of hours. Please advise!

Thanks a lot!

 

[Greg Bernhardt]

Air density, like air pressure, decreases with increasing altitude. The density of the air at sea level is about 1.225 kg/m3. At 12,000 ft the density of the air is about 0.841 kg/m3.

The density of air is 0.0012 kg/m3 at 0 °C and 101.325 kPa.