Length

The length is a physical quantity.

They referred to each other, the extent of physical objects and their distances. It is defined via measurement requirements and the length standards. The symbol length is the lowercase letter "l", its SI unit of meters m. For paths and curve lengths is used as symbols.

As part of the SI unit system, the length is a basic size, are made ​​up of the other sizes.

The length measurement is made by comparing the length to be measured with standards of known length. The length of intervals between two points or a scale is considered in classical physics as a constant. In the special theory of relativity, however, the length depends on the relative state of motion of each observer, one speaks of a relativistic length contraction.