|
|
||||||||||||||||
|
|
||||||||||||||||
|
Definitions of the Seven Basic S I Units
Derived Units of the S I |
|||||||||||||||
|
|
||||||||||||||||
The Prefixes of the S IThe S I allows the sizes of units to be made bigger or smaller by the use of appropriate prefixes. For example, the electrical unit of a watt is not a big unit even in terms of ordinary household use, so it is generally used in terms of 1000 watts at a time. The prefix for 1000 is kilo so we use kilowatts [kW] as our unit of measurement. For makers of electricity, or bigger users such as industry, it is common to use megawatts [MW] or even gigawatts [GW]. The full range of prefixes with their [symbols or abbreviations] and their multiplying factors which are also given in other forms is |
||||||||||||||||
The U S System of MeasurementsMost of the US system of measurements is the same as that for the UK. The biggest differences to be noted are in Capacity which has both liquid and dry measures as well as being based on a different standard - the US liquid gallon is smaller than the UK gallon. There is also a measurement known at the US survey foot. It is gradually being phased out as the maps and land plans are re-drawn under metrication. (The changeover is being made by putting 39.37 US survey feet = 12 metres) |
||||||||||||||||
|
||||||||||||||||
|
|
||||||||||||||||
| ||||||||||||||||