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Physics vocabulary · Measurement and Units

Dimensional analysis

Meaning in physics, with examples

nounCommon term

In physics, dimensional analysis means: A method of checking or building an equation by comparing the units or basic dimensions (mass, length, time and so on) on each side. Both sides of a valid equation must match.

In Turkish: boyut analizi, birim analizi

How it is used

Dimensions are written in square brackets: [M], [L], [T]. Dimensional analysis can prove that an equation is wrong but not that it is right, because it cannot detect missing numbers such as ½ or 2π. In class it is often called a 'units check'.

Example sentences

  1. Use dimensional analysis to check that √(gh) has the units of a speed.

  2. Dimensional analysis suggests that the period of a pendulum depends on its length and on g, but not on its mass.

Common collocations

  • check the units
  • base dimensions
  • dimensionally consistent
  • homogeneous equation
  • SI unitsThe international system of measurement units used in science, based on seven base units such as the metre, kilogram, second, ampere and kelvin. SI comes from the French 'Système international'.
  • deriveTo obtain an equation or result step by step from basic laws or other equations, using logic and algebra instead of simply quoting it.
  • order of magnitudeThe approximate size of a number expressed as the nearest power of ten. Two values that differ by a factor of about ten differ by one order of magnitude.
  • scientific notationA way of writing very large or very small numbers as a number between 1 and 10 multiplied by a power of ten, for example 3.0 × 10⁸ instead of 300,000,000.

More terms: Measurement and Units

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