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| Dimensional Formulae and Dimensional Equation |
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| It is the term which tells about the power with which a fundamental quantity is contained in a physical quantity. |
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| E.g., Dimensional formula of velocity is [LT-1], that of density is [ML-3] |
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| In general, [X] = [Ma Lb Tc] |
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| RHS represents dimensional formula of physical quantity X, whose dimensions in mass, length and time are a, b and c respectively. |
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| When velocity is defined using the fundamental units of mass, length and time, we have |
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| when there is no mass, M0 = 1 (algebraic theory of indices). |
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| This is the dimensional formula for velocity and we can draw the following inference. |
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 Unit of velocity depends on the unit of length and time and is independent of mass. |
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 In the unit of velocity, the power of L and T are 1 and -1 respectively. |
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| E.g., Formula for density is ML-3 |
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| Formula for force is MLT-2 |
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| The dimensional formula of a physical quantity can be obtained by defining its relation with other physical quantities and then expressing these quantities in terms of mass [M], length [L] and time [T]. |
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| The dimensional formulae of some of the physical quantities is given below |
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