SI units

Introduction :

The SI system (International System of Units) is the modern metric system of measurement and the dominant system of international commerce and trade. SI units are gradually replacing Imperial and USCS units.

The SI is maintained by the International Bureau of Weights and Measures (BIPM, for Bureau International des Poids et Mesures) in Paris.
The SI system is founded on the

• SI base units
• SI derived units described in terms of acceptable SI units
• SI derived units with special names and symbols acceptable in SI
• SI Prefixes

SI Base Units

The core of the SI system is a short list of base units defined in an absolute way without referring to any other units. The base units are consistent with the part of the metric system called the MKS system. The International System of Units (SI) is founded on seven base units.

 

SI Derived Units with Special Names and Symbols acceptable in SI

Derived units are algebraic combinations of the seven base units and the two supplementary units with some of the combinations being assigned special names and symbols.


 

 

SI Derived Units described in Terms of acceptable SI Units

Derived units are algebraic combinations of the seven base units and the two supplementary units with some of the combinations being assigned special names and symbols.

SI Prefixes

 

 

The prefixes provide an order of magnitude: Ex.

• 16600 m = 16.6 10³ m = 16.6 km
• 1 mm³ = (10^-3 m)³ = 10-9 m³