Unit And Dimension

1.Physical Quantity
     A quantity which can be                measured and by which various physical happening can be explained and expressed in the form of law is called physical quantity.
 For example length,mass,time,force etc.
Physical quantity = Magnitude×Unit 
                               = n×u
Example :-
                    Length =9 m = const.
                    N×U=n×u
2.Types of physical quantities 
        a.Scalar quantity = These qualitiy do not have any direction and only have magnitude.
For example = time,energy,work ect.
It follows simple addition, subtraction laws of math.
        b.Vector quantity = These quantities have both magnitude and direction. 
For example = velocity, acceleration force etc.
It can be added or subtracted by law of vector addition.
3.Fundamental quantities
Quantities which are independent of all other quantity and do not required the help of other physical quantity for their definition therefore it is also called absolute quantities. 
Ex. Length(m), mass(kg),time(s) etc

4.Derived quantities 
All other quantities can be derived by the suitable multiplication and division of different power of fundamental quantities. 
Ex. Velocity derived from length(m)÷time(s).

5.System of units 
CGS = cm,g,s.
FPS = Foot,pound,second (s).
S.I or MKS = m,kg,s.
    

Dimension will be continue in next session.

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