Question

Mach number is a measure of the directed motion of the gas compared with the random thermal motion of the molecules.

(a) False

(b) True

This question was posed to me during an interview for a job.

The origin of the question is The Basic Normal Shock Equations in chapter Normal Shock Waves of Aerodynamics

Answer 1

Right answer is (b) True

The best I can explain: This comes from the physical meaning of the Mach number. When we take the ratios of per unit mass kinetic energy to the potential energy of the fluid particle moving along a streamline, it comes proportional to the square of the Mach number. Thus, this is true.