## Unuts, Conversion Factors and Constants

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, m ^{2 }, but can also be measured in square millimetres, mm ^{2 }, square centimetres, cm ^{2 }, square kilometres, km ^{2 }, or square miles.

1 square mile = 2.56 km ^{2 } = 2560000 m ^{2 } =25600000000 cm ^{2 } =2560000000000 mm ^{2 } (using 1 mile = 1.6 km)

Volume is usually measured in cubic metres, m ^{3 }, but can also be measured in cubic millimetres, mm ^{3 }, cubic centimetres, cm ^{3 }, cubic kilometres, km ^{3 }, or cubic miles.

1 cubic mile = 4.096 km ^{3 } = 4096000000 m ^{3 } =256000000000000 cm ^{3 } =256000000000000000 mm ^{3 }

(using 1 mile =1.6 km)

It is important that areas transform as, for example, 1m ^{2 } =(100cm) ^{2 } =10000 cm ^{2 } and 1m ^{3 } =(100cm) ^{3 } =1000000 cm ^{3 }