Ideal Gas Law

Pressure, density and temperature of a gas are related through an equation of state. Under ordinary conditions for air,

$$p = \rho R T$$ (1.17)

where p is the absolute pressure, $\rho$ the density, T the absolute temperature and R is a gas constant. The above equation is called the Ideal Gas Law or the Perfect Gas Equation. The gases obeying this equation are called Ideal Gases.

The gas constant R (Ideal Gas Law ) is given by

$$R = {\Re \over M}$$ (1.18)

where $\Re$ is called the universal gas constant and is equal to 8314 J/kg.K. For air the gas constant R = 286.9 J/kg.K .

(c) Aerospace, Mechanical & Mechatronic Engg. 2005
University of Sydney