noun
Mach number
A dimensionless quantity in fluid dynamics representing the ratio of flow velocity to the speed of sound. Used in aerospace and physics contexts.
この飛行機はマッハ数2で巡航できる。
This aircraft can cruise at Mach 2.
マッハ数が1を超えると衝撃波が発生する。
When the Mach number exceeds 1, shock waves are generated.