What is k=1.4?

Given,

Pressure = 1 bar

Speed (V) = 1800 km / hr = 500 m/s

K = 1.4

R = 287 J/kg K

Temperature (t) = 10˚ C

T = 10 + 273 = 283 k

As we know, the velocity of sound is (adiabatic process) -

$C = \sqrt{KRT} = \sqrt{1.4 \times 287 \times 283}$

$C = 337.20\ m/s.$

$\therefore\ Mach\ Number\ = \frac{v}{c} = \frac{500}{337.20} = 1.48$

$Also,\ Mach\ angle\ is,\ Sin \alpha \frac{c}{v} = \frac{1}{m}$

$\therefore \alpha = sin^{-1} (\frac{1}{1.48})$

$Mach\ angle\ is\ \alpha = 42.40˚$

So, finally Mach number is 1.48 and Mach Angle is 42.40.