Question

What is the mach number of an aircraft flying in air at a pressure of 101306N/m^2 and velocity 556m/s?

(a) 1.634

(b) 2.145

(c) 0.125

(d) 1.225

I have been asked this question in examination.

I'd like to ask this question from Measurement of Mach Number topic in division Atmosphere and Air Data Measurement of Aircraft Performance

Answer 1

The correct choice is (a) 1.634

To elaborate: The answer is 1.634. Given P=101306N/m^2, V=556m/s. We know that ρ and γ of air are ρ=1.225kg/m^3 and 1.4. From the equation M=V\(\sqrt{\frac{\rho}{\gamma P}}\)

On substituting and solving,

M=556\(\sqrt{\frac{1.225}{1.4*101306}}\)

M=1.634.