Units and Measurements

Units and Measurements

by LAKSHYA Darshan Dhokiya

​Units and Measurements

​What are Units?

​•Units are standards for measurement of physical quantities

•Eg :- newton,second,metre etc

​Systems of Units

​•(i) CGS: Centimetre Gram Second system

•(ii) MKS: Metre Kilogram Second system

•(iii) FPS: Foot Pound Second system.

•(iv) SI: System International

​What are Measurements?

•A measurement always involves a comparison with a standard measuring unit which is internationally accepted.

•Measurements consist of 2 things:

Magnitude and Unit

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​Types of Quantity

​1.Physical Quantity

2.Non-Physical Quantity

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​1.Physical quantity

​The quantity that can be measured are called physical quantity

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Eg-Length,mass,time,temperature etc

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​2.Non-Physical Quantity

​•The quantity that cannot be measured are called Non-Physical Quantity

•Eg :- Roads,buses,buildings

​Physical Quantity

​Fundamental quantity

​•The physical quantities which do not depend on any other physical quantities for their measurements are known as fundamental quantities.

•Eg:- Length,Mass,Temperature etc

​The Quantity which depends on Fundamental Quantity Are called Derived Quantity

Eg:-Force,Momentum,Power

​Derived Quantity

​Quantity SI Units Symbol

1) Length metre m

2) Mass kilogram kg

3) Time second s

4) Temperature kelvin K

​5) Electric current ampere A

6) Luminous Intensity candela cd

7) Amount of substance mole mol

​Supplementary Quantity

​Quantity SI Units Symbol

Plane Angle radian rad

Solid Angle steradian sr