Question

In terms of compressibility, the density change when pressure of the fluid increases is ______

(a) Density increases

(b) Density decreases

(c) Density is constant

(d) Insufficient data

The question was asked in a job interview.

This interesting question is from Definition of Compressibility topic in chapter Compressible Flow – Preliminary Aspects of Aerodynamics

Answer 1

Correct answer is (a) Density increases

For explanation: The formula for compressibility when expressed in terms of density gives a direct relation between pressure change and density change. i.e. dρ = ρ τ dp. Hence, when the pressure increases density of the fluid increases.