This 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.
He finished his homework at lightning speed.
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.