Mach number defined as the square root of the ratio of the inertia force of a flowing fluid to the elastic force.

$\therefore \text{Mach Number} = M = \sqrt \frac{ \text{Inertia force} }{ \text{Elastic force} } = \sqrt \frac{\rho AV^2}{KA}$

$M = \sqrt \frac {V^2}{K/ \rho } = \frac{V} {\sqrt …