**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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