Dimensional formulae

Dimensional analysis is a tool to understand the properties of physical quantities independent of the units used to measure them. Every physical quantity is some combination of mass, length, time, electric charge, and temperature, (denoted M, L, T, Q, and T, respectively). For example, speed, which may be measured in meters per second (m/s), miles per hour (mi/h), or some other units, has dimension expresses as  L/T or alternatively    LT ^-1.

Dimensional analysis is routinely used to check the plausibility of derived equations and computations. It is also used to form reasonable hypotheses about complex physical situations that can be tested by experiment or by more developed theories of the phenomena, and to categorize types of physical quantities and units based on their relations to or dependence on other units, or their "dimensions", or their lack thereof.

The dimensions of a physical quantity are associated with combinations of mass, length, time, electric charge, and temperature, represented by sans-serif symbols M, L, T, Q, and T, respectively, each raised to rational powers. Dimensional formulae of some derived quantities