http://www.ck12.org Chapter 26. Physics Glossary
26.2 D
dimensional analysis
In physics and all science, dimensional analysis is a tool to find or check relations among physical quantities by
using their dimensions. The dimension of a physical quantity is the combination of the basic physical dimen-
sions (usually length, mass, time, electric current, temperature, amount of substance, and luminous intensity)
which describe it; for example, speed has the dimension length per time, and may be measured in meters per
second, miles per hour, or other units. Dimensional analysis is based on the fact that a physical law must be
independent of the units used to measure the physical variables. A straightforward practical consequence is
that any meaningful equation (and any inequality and inequation) must have the same dimensions in the left
and right sides. Checking this is the basic way of performing dimensional analysis.
displacement
The change in position, a vector quantity.
distance
The separation between two points, a scalar quantity.