Length (physics)

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Physical size
Surname length
Formula symbol
Size and
unit system
unit dimension
SI m L.
cgs cm L.
Planck Planck length L.
Astronomic lj , AE , pc L.
See also: Path length (s), distance (r), height (h), radius (r),
diameter (d), circumference (u), wavelength (λ), u. v. a.

The length is a physical quantity that indicates the extent of physical objects and their distances from one another. The symbol for length is the lower case letter , its SI unit is the meter . A formula symbol is usually used for the length of paths and curves . In the SI system, the length is a basic quantity .

The length measurement is carried out by comparing the length to be measured with scales of known length. The length of the distances between two points or a scale is considered constant in classical physics. In the special theory of relativity , however, the length depends on the relative state of motion of the respective observer; one speaks of a relativistic length contraction .


The noun mhd. Lenge , ahd. Lengī , like the adjective lang ( mhd. Lanc , ahd. Lang ), goes back to idg. Longho-s "lang".

See also

Individual evidence

  1. ^ The dictionary of origin (=  Der Duden in twelve volumes . Volume 7 ). Reprint of the 2nd edition. Dudenverlag, Mannheim 1997 ( p. 403 ). See also Friedrich Kluge : Etymological dictionary of the German language . 7th edition. Trübner, Strasbourg 1910 ( p. 277 ).