Question

The equation of state for a perfect gas is p = δRT, where R is______ (for air at standard conditions).

(a) 287 kJ/kg.K

(b) 8314 kJ/kg

(c) 8.314 kJ/kgK

(d) 287 J/kg.K

I had been asked this question in exam.

I'd like to ask this question from A Brief Review of Thermodynamics in chapter Compressible Flow – Preliminary Aspects of Aerodynamics

Answer 1

Right choice is (d) 287 J/kg.K

The explanation is: The universal gas constant R in the equation of gas has different values for different gases and at different conditions. For air at standard conditions, the correct value is 287 J/kg.K (check units).