Fractions and multiples

Sometimes, the fundamental units defined above are inconveniently large or incon­veniently small for a particular case. In such cases, the quantity can be expressed in terms of some fraction or multiple of the fundamental unit. Such multiples and fractions are denoted by appending a prefix to the symbol denoting the fundamental unit. The prefixes most used in aerodynamics are:

M (mega) – denoting one million к (kilo) – denoting one thousand m (milli) – denoting one one-thousandth part H (micro) – denoting one-millionth part

Thus

1MW= 1000 000W 1 mm = 0.001 m 1 /лп 0.001 mm

A prefix attached to a unit makes a new unit. For example,

1mm2 = 1 (mm)2 = 10_6m2, not 10-3m2 For some purposes, the hour or the minute can be used as the unit of time.