International System of Units - SI
By many triumphs of diplomacy and horse trading the world agreed to adopt an International System of Units – (SI) so that they could work together.
The SI is at the centre of all modern science and technology and consists of seven base units.
SI base units
| Quantity | SI Unit | Symbol | Example |
|
Length |
metre | m | Height of double-decker bus: about 4.5 m |
|
Mass |
kilogram |
kg | Large loaf of bread: about 0.8 kg |
|
Time |
second |
s | Time between heart-beats (at rest): about 0.8 s |
|
Electric current |
ampere |
A | Kettle: about 10 A |
|
Temperature |
kelvin |
K | Human body: about 310 K |
|
Luminous intensity |
candela |
cd | Candle: about 1 cd |
|
Amount of substance |
mole |
mol | Water molecules in a cupful: about 14 mol |
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