Measurement and Dimensions – Physics First chapter

Unit one (1)
1.1 Measurement and Dimensions

1 : physical Quantity :- Those physical Quantity which was some existence and measurable are known as physical quantity. Eg distanc, time , weight , velocity ,work etc
Types of physical Quantity:-
i> Fundamental Quantities :
Those physical quantities which give own meaning it self and depend upon other physical quantities are called fundamental quantities eg : , mass etc.
ii> Derived Quantities:
Those physical quantity which do not give own meaning itself and depend upon other physical quantities eg. Force, work , power etc.

2. Dimensions:-
i> Dimensional Formula :-
That arrangement inside the capital bracket contain there fundamental quantities like mass (M) and length (L) and time (T) such arrangement is called dimensional formula( MLT)
Questions :
Find the Dimensional Formula and dimensions of physical quantity .
i> Length = [L] =
= [ML^1T]
Dimensional power:-
The power contains in mass length and time is called Dimesions. The Dimensions of length in mass is zero on length is one and time is zero.
ii> Mass = [M] = [M1 L0 T0 ]
Dimensional formula
The Dimension of mass is “1” length and time is “o”
1

Velocity :- (V) Velocity is Defined as distance travel by the time= d/t= (L/T)
= [m0L1T-1]
: Dimensional formula === >> Mass = 0 , Length = 1 , Time = -1

iv) Acceleration (α) :- Velocity/ Time = V/T
[l1T-1]/ t
= [M* L1T-2]

The dimensional of acceleration is
Mass = 0
Length = 1
Time = -2
v) Force (F) = m*a = m*d/t*t
=[M1L1T-2]

Vii Work :- Distance * force (L*M*L*T-2)= [ ML=-2]
The Dimension of work is
Mass= 1
Length=2
Time= -2

Vii> power (p) =- Work/time
= [ m1l2T-2]/T
The dimension of power is
Mass = 1
Length = 2
Time = -3

Applications of Dimensional Formula
Qno1 : Check the correctness of a given physical equation.
-To explain this statement take an example
Eg. V2 = u2+2as
LHS -V2 = (D/T)2 = [ L/T]2 = [L2T-2]
Therefore : [ M* L2T-2] = LHS

RHS = u2+2as= d2/t2 + 2 [LT-2l]
[L2T-2] + [ L2T-2]
2[M0L2+T-2]
1[M0L2+T-2]

LHS= RHS proved..

Other important Questions and exercise

Measurement and Unit Important questions | Grade VIII

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