Physical Quantity: Anything that can be measured directly or indirectly.
Fundamental or Base Quantities: Basic non-derivable quantities (length, mass, time, electric current, thermodynamic temperature, amount of substance and luminous intensity)
Derived quantities: Quantities which are obtained from one or more fundamental quantities eg: velocity, acceleration
Supplementary Quantities: eg: solid angle, plane angle
Unit is the reference standard used to measure physical quantity.
Fundamental units: The reference standard used to measure fundamental physical quantities. (metre (m), kilogram (kg), second (s), ampere (A), Kelvin (K), mole (mol), candela(cd))
Derived units: The reference standard used to measure derived physical quantities. Eg newton, pascal, m/s
Supplementary units: The reference standard used to measure supplementary physical quantities. (for plane angles, radian, for solid angle – steradian) radian=length of arc/radius, steradian = intercepted area of sphere/radius
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