N-UNCOUNT
馬赫(速度單位，1馬赫等于1倍音速)
Mach is used as a unit of measurement in stating the speed of a moving object in relation to the speed of sound. For example, if an aircraft is travelling at Mach 1, it is travelling at exactly the speed of sound.
例句
The hot air permitted higher speeds before the critical Mach number was exceeded...
熱空氣可使之在超過臨界馬赫數(shù)之前達到更快的速度。
The aim is to fly at about Mach 2, twice the speed of sound.
目標是以大約2馬赫的速度飛行，也就是音速的兩倍。