Class 11 > Unit # 01: Physical Quantities & Measurements > Basic, Derived & Supplementary Quantitites

Define Fundamental SI units, derive units and supplementary units for various measurements.

FUNDAMENTAL UNITS

The International System of Units (SI) is built upon seven independent physical quantities. The units assigned to these base quantities are known as Fundamental or Basic Units, serving as the foundational pillars from which all other measurements are derived:

Quantity	Unit Name	Symbol
Length	meter	m
Mass	kilogram	kg
Time	second	s
Electric Current	ampere	A
Temperature	kelvin	K
Amount of Substance	mole	mol
Luminous Intensity	candela	cd

DERIVED UNITS

The units that require mathematical combinations of two or more fundamental base units (either through multiplication or division) are called Derived Units. They are utilized to measure complex geometric, kinetic, and dynamic quantities:

Quantity	Unit Name	Symbol / Base Equivalency
Area	Square meter	m²
Volume	Cubic meter	m³
Density	Kilogram per meter cube	kg/m³
Velocity	Meter per second	m/s
Force	Newton	N  ($\text{kg}\cdot\text{m/s}^2$)
Work	Joule	J  ($\text{N}\cdot\text{m}$)
Power	Watt	W  ($\text{J/s}$)

SUPPLEMENTARY UNITS

Supplementary units are geometric units that are traditionally treated as dimensionless quantities within the International System of Units (SI). They are uniquely categorized to formally express purely structural angles that cannot be purely classified as either base or standard derived physical attributes:

Quantity	Unit Name	Symbol
Plane Angle	Radian	rad
Solid Angle	Steradian	sr