Question

The ratio of specific heats (γ) of air is _________

(a) 1.6

(b) 1.7

(c) 1.4

(d) 1.8

The question was asked in an internship interview.

My question is based upon Characteristics of Atmosphere in section Atmosphere and Air Data Measurement of Aircraft Performance

Answer 1

Correct choice is (c) 1.4

For explanation: The ratio of specific heats (γ) of air is 1.4. Ratio of specific heats is the ratio of specific heat of air at constant pressure to the specific heat of air at constant volume, i.e. \(\frac{C_p}{C_v}\)=γ. Cp of air is 1.008 kJ/kg-K; Cv of air is 0.721 kJ/kg-K at standard levels. So γ=\(\frac{1.008}{0.721}\)=1.4.