# Units, Conversion Factors and Constants

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Distance is usually measured in metres, m, but can also be measured in centimetres, cm, millimetres, mm, kilometres, km or miles.

1 mile=1.609 km (often approximated to 1.6) = 1609 metres (often approximated to 1600) = 160900 cm = 1609000 mm

Speed is usually measured in metres per second, m/s, or kilometres per hour, km/h, or miles per hour, mph.

1 m/s =3.6 km/h =2.25 mph (using 1 mile =1.6 km)

Time is usually measured in seconds but can also be measured in minutes, hours, days and years.

1 minute = 60 seconds

1 hour = 60 minutes = 3600 seconds

1 day = 24 hours = 86400 seconds

1 year = 365 days = 31536000 seconds

Area is usually measured in square metres, m2, but can also be measured in square millimetres, mm2, square centimetres, cm2, square kilometres, km2, or square miles.

1 square mile = 2.56 km2 = 2560000 m2 =25600000000 cm2 =2560000000000 mm2 (using 1 mile = 1.6 km)

Volume is usually measured in cubic metres, m3, but can also be measured in cubic millimetres, mm3, cubic centimetres, cm3, cubic kilometres, km3, or cubic miles.

1 cubic mile = 4.096 km3 = 4096000000 m3 =256000000000000 cm3 =256000000000000000 mm3

(using 1 mile =1.6 km)

It is important that areas transform as, for example, 1m2 =(100cm)2 =10000 cm2 and 1m3 =(100cm)3 =1000000 cm3