The Mach Number is named after the Austrian physicist Ernst Mach.

Mach 1 is the speed of sound, which is approximately 760 miles per hour at sea level.

An airplane flying less than Mach 1 is traveling at subsonic speeds, faster than Mach 1 would be supersonic speeds and beyond Mach 5 would be hypersonic.

Austrijos fiziko Ernst Mach garbei pavadintas grci vienetas yra garso greitis 760 myliu per valanda juros lygyje (~1200 km/val)

Lekuvas skrendantis greiciau nei garso greitis M>1 yra virsgarsinis,
- o ji M>5, tai vadinamas super garsiniu arba ultra garsiniu [haipersonik] lektuvu.

taip beveik kasdien is londono i sidneju i darba galima skraidyti :)