# A jet is flying at a speed of 356 m/s in an air temperature of 25 C. What is the Mach number of the jet?

Relevance

v(j) = velocity of jet = 356 m/s

v(s) = velocity of sound = to be determined

M = Mach number = to be determined

The speed of sound [v(s)] depends on the type of medium through which the sound is

traveling and the density of the medium.

Air temperature = 25 °C

γ = (gamma) ratio of specific heats = 1.4 for air at STP*

*standard temperature and pressure

R = gas constant = 286 m²/s²/K for air

T = absolute temperature (273.15 K + °C) = 298.15 K

v(s) = speed of sound = to be determined

v(s) = √(γRT)

v(s) = 345.5130388 m/s ≈ 346 m/s

M = v(j)/v(s)

M = 1.030351854 ≈ 1.03

• A big piece of the puzzle missing here to solve this.

''What is the density altitude ?? '' or is this sea level.

That would equate to just over mach 1.

• From https://www.weather.gov/epz/wxcalc_speedofsound , the speed of sound in air at 25°C is 346.06 m/s. If the jet is flying at 356 m/s, then it's mach number would be

356/346.06 = mach 1.03.