9.0.0. DIMENSION OF PHYSICAL QUANTITIES

9.0.0QUANTITIES:ON OF PHYSICAL QUANTITIES
Dimension of a physical quantity shows the quantities that make up the physical quantity. It also shows how the quantities that make up the physical quantity are related.

DERIVATION OF DIMENSION OF PHYSICAL QUANTITIES
The derivation of the dimension of a physical quantity is similar to what we did above when we where showing that a given quantity is a derived quantity.


STEPS TO FOLLOW:
• Know the formula of the quantity whose dimension you want derived or find
• Write down the formula of the quantity
• Take note of other quantities that are present in the formula of the quantity whose dimension you want derived
• Know their symbol
• Replace those quantities with their symbols.

WORKED EXAMPLE
What is the dimension of density?

Solution :
Step I :
formula of density
step II :
write down formula of density,
Density = mass / volume  = mass / l x b x h
Step III :
what are the quantities that are present in the formula of density?
The quantities that are present are l,b and h
Length and breadth and height are the same , then l = b =h . we call all of them length. Ok!
Step IV:
Symbol of length is L, symbol of mass is M
Step V :
Replace the quantities with their symbols
We will have,
Dimension of density = M/L^3 . simple!

NOTE: IN DIMENSION, WE USE THE SYMBOL OF THE NAME OF THE QUANTITY AND NOT THED SYMBOLS OF THE UNITS OF THE QUANTITIES.