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Waves
Waves

Mach Number

M=vvsoundM = \frac{v}{v_{sound}}

Ratio of object speed to speed of sound. M > 1 is supersonic.

Variables

M
Mach number
Dimensionless velocity ratio
unitless
v
Object velocity
Speed of moving object
m/s
v_sound
Speed of sound
In the medium
m/s

Derivation

By definition. M < 1 subsonic, M = 1 sonic, M > 1 supersonic, M > 5 hypersonic.

Your notes

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Common questions

What is the Mach Number formula?

Mach Number is written M = frac{v}{vₛₒᵤₙd}. Ratio of object speed to speed of sound. M > 1 is supersonic. It belongs to Waves, under Sound Waves.

What are the units in M = frac{v}{vₛₒᵤₙd}?

In SI units, M is mach number (dimensionless); v is object velocity, measured in m/s; v_sound is speed of sound, measured in m/s.

How is the Mach Number formula derived?

By definition. M < 1 subsonic, M = 1 sonic, M > 1 supersonic, M > 5 hypersonic. The result is M = frac{v}{vₛₒᵤₙd}.