Mach; Mach number
Technical term for the ratio of speed to the speed of sound. Often used in compounds like マッハ数.
See also: マッハ数
この戦闘機はマッハ2で飛行できる。
This fighter jet can fly at Mach 2.
That fighter jet can fly at Mach 2.
at high speed; very fast
Colloquial use, often as マッハで, meaning 'at breakneck speed' or 'extremely quickly'. Not a precise measurement.
彼はマッハで宿題を終わらせた。
He finished his homework at lightning speed.
彼はマッハで宿題を終わらせた。
He finished his homework at lightning speed.
マッハ (Mach, a speed unit) and バッハ (Bach, the composer's name) sound very similar but are unrelated words.
From German 'Mach', named after physicist Ernst Mach. The colloquial sense derives from the idea of supersonic speed.