Unit and it's characteristics and it's types.
Unit : The chosen standard of the same kind (as that of given physical quantity) taken as reference in the measurement of a physical quantity is called unit.
Characteristics of a standard unit :(i) It should be well defined.
(ii) It should be of suitable size.
(iii) It should be easily reproducible at all places.
(iv) It should not change with time and from place to place.
(v) It should be easily accessible.
Types of unit : Two types
(i) Fundamental Units (ii) Derived Units.
(i) Fundamental Units : The units selected for measuring the fundamental quantities (mass, length and time) are called fundamental units.
Unit of mass is kilogram(kg).
Unit of length is metre(m).
Unit of time is second(s).
(ii) Derived Units : The units of derived physical quantities(area, speed,velocity, force etc.)are called derived units because they have derived from fundamental units. For e.g.
Speed = Distance/Time = m/s
Therefore m/s is the Derived Units.
(i) Fundamental Units : The units selected for measuring the fundamental quantities (mass, length and time) are called fundamental units.
Unit of mass is kilogram(kg).
Unit of length is metre(m).
Unit of time is second(s).
(ii) Derived Units : The units of derived physical quantities(area, speed,velocity, force etc.)are called derived units because they have derived from fundamental units. For e.g.
Speed = Distance/Time = m/s
Therefore m/s is the Derived Units.
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