Question

Specific heat for gas is almost constant in the case of_______

(a) Space vehicle

(b) High-temperature flow

(c) Air in a desert

(d) Chemically reacting flow at high- speeds

This question was posed to me in semester exam.

This is a very interesting question from A Brief Review of Thermodynamics topic in chapter Compressible Flow – Preliminary Aspects of Aerodynamics

Answer 1

Correct option is (c) Air in a desert

Explanation: Instances of very high temperature, chemically reacting flow at high-speeds do not have constant specific heats. Space vehicles fall in this category. The air in any desert would not have temperatures higher than 1000K and thus fall in the category of calorically perfect gas (i.e. constant specific heat).