The document explains the dimensions of physical quantities, defining them in terms of fundamental quantities with specific notation, such as [l] for length and [t] for time. It describes rules for writing dimensions and highlights the benefits, including ease of converting derived quantities and using dimensional analysis for predicting formulas. Additionally, it mentions that plane and solid angles are dimensionless quantities.

1. Dimensions of Physical Quantities

2. Definition
 Dimensions of physical quantities means
expressing them in terms of fundamental
quantities by raising them to certain powers
 Dimensions are always expressed in [] brackets

3. Some Examples
 Dimension of Length is [L]
 Dimension of Time is [T]
 Dimension of Mass is [M]
 By using dimensions we can express any derived
quantity in terms of fundamental quantities

4. Rules for writing Dimensions
 Always write dimensions in [ ] bracket
 The powers are simply raised to zero if the
physical quantity is independent of a fundamental
quantity
 Consider velocity which is rate of change of
displacement with respect to time, its dimension
will be [LT-1]
 Plane angle and solid angle are dimensionless
quantities

5. Benefits of using dimensions
 We can easily convert derived quantities in terms
of fundamental quantities
 Dimensions are used in dimensional analysis
where we predict formulae of certain quantities
and their dependence on physical quantities
 For example, if temperature of a body depends
on mass and length of the body, we can easily
derive a formula for that

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