Quick Reference
MEASUREMENT
Glossary of Mathematics | Measurement | Areas and Volumes
SI UNITS
A system of coherent metric units proposed for international acceptance in 1960 and now recognised world wide. It comprises 7 base and 2 supplementary units.
UNIT |
SYMBOL |
QUANTITY |
| metre | m | Length |
| kilogramme | kg | Mass |
| second | s | Time |
| ampere | A | Current |
| kelvin | K | Temperature |
| candela | cd | Luminous intensity |
| mole | mol | Relativemolecular mass |
| radian | rad | Plain angles |
| steradian | sr | Solid angles |
The 9 SI Units can be combined to form derived units. for example, the unit of force (Newtons) is derived thus: kg m s-2 . Each unit can be prefixed with a further symbol or index to indicate the magnitude of the unit. So for example: 1000m = 1 x 103 =1km
SI PREFIXES
SYMBOL |
NAME |
VALUE |
| G | giga | 109 1 000 000 000 |
| M | mega | 106 1 000 000 |
| k | kilo | 103 1 000 |
| h | hecto | 102 100 |
| da | deca | 101 10 |
| d | deci | 10-1 0.1 |
| c | centi | 10-2 0.01 |
| m | milli | 10-3 0.001 |
| µ | micro | 10-6 0.000 001 |
| n | nano | 10-9 0.000 000 001 |
CONVERSION FACTORS
MULTIPLY |
BY |
TO GET |
LENGTH |
||
| millimetres | 0.039 | inches |
| metres | 3.28 | feet |
| metres | 1.0936 | yards |
| kilometres | 0.621 | miles |
| inches | 25.4 | millimetres |
| feet | 304.8 | millimetres |
| yards | 0.914 | metres |
| miles | 1.609 | kilometres |
AREA |
||
| metres² | 1.196 | yards² |
| feet² | 0.093 | metres² |
| yards² | 0.836 | metres² |
| yards² | 4 840 | acre |
| miles² | 640 | acres |
VOLUME |
||
| centimetre³ | 0.061 | inches³ |
| metres³ | 1.308 | yards³ |
| metres³ | 35.315 | feet³ |
| inches³ | 6.452 | centimetre³ |
| feet³ | 0.028 | metres³ |
| yards³ | 0.836 | metres³ |
SPEED |
||
| miles/hour | 1.609 | kilometres/hour |
| kilometres/hour | 0.621 | miles/hour |
MASS |
||
| grammes | 0.035 | ounces |
| kilograms | 2.205 | pounds |
| tonnes | 0.984 | tons |
| ounces | 28.350 | grammes |
| pounds | 0.454 | kilograms |
| tons | 1.016 | tonnes |
CAPACITY |
||
| gallons | 4.546 | litres |
| litres | 0.220 | gallons |
PRESSURE |
||
| pounds/inch² | 0.0689 | bar |
| bar | 14.5 | pounds/inch² |
ENERGY |
||
| horsepower | 0.7457 | kilowatts |
| kilowatts | 1.341 | horsepower |
