Class 11 Physics Units and Measurements Dimensional Analysis

Dimensional Analysis

  • Only those physical quantities which have same dimensions can be added and subtracted. This is called principle of homogeneity of dimensions.
  • Dimensions can be multiplied and cancelled like normal algebraic methods.
  • In mathematical equations, quantities on both sides must always have same dimensions.
  • Arguments of special functions like trigonometric, logarithmic and ratio of similar physical quantities are dimensionless.
  • Equations are uncertain to the extent of dimensionless quantities.

 

Example Distance = Speed x Time. In Dimension terms, [L] = [LT-1] x [T]

Since, dimensions can be cancelled like algebra, dimension [T] gets cancelled and the equation becomes [L] = [L].

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