Block, SkipCaptcha, apieditor, Automoderated users, Bots, edit, ratelimit-exempt
58,183
edits
Changes
Jump to navigation
Jump to search
Line 105:
Line 105: − +
→Length: Spelling/Grammar Check, typos fixed: Therefore → Therefore,
The base unit of length, and originally the unit from which all other definitions flowed, is the [[meter]]. The original definition was "one ten-millionth the distance from the equator to the north pole." Lagrange's surveyors computed this distance (probably using a variation on Eratosthenes' tropical-shadow experiment) and inscribed it on a metal bar that they kept at the weights-and-measures headquarters building in Sèvres, [[France]].
The base unit of length, and originally the unit from which all other definitions flowed, is the [[meter]]. The original definition was "one ten-millionth the distance from the equator to the north pole." Lagrange's surveyors computed this distance (probably using a variation on Eratosthenes' tropical-shadow experiment) and inscribed it on a metal bar that they kept at the weights-and-measures headquarters building in Sèvres, [[France]].
But this artifact, being made of metal, tended to expand and contract. Centuries later, when the scientific community realized what had happened, the task of re-standardizing all meter sticks to the equator-to-pole-times-10<sup>−7</sup> definition was judged too onerous. Therefore the meter was redefined. At first it was defined as 1,650,763.73 wavelengths of the orange-red line in the excitation spectrum of [[krypton]]-86. Today it is defined as 1⁄299,792,458th of a light-second.
But this artifact, being made of metal, tended to expand and contract. Centuries later, when the scientific community realized what had happened, the task of re-standardizing all meter sticks to the equator-to-pole-times-10<sup>−7</sup> definition was judged too onerous. Therefore, the meter was redefined. At first it was defined as 1,650,763.73 wavelengths of the orange-red line in the excitation spectrum of [[krypton]]-86. Today it is defined as 1⁄299,792,458th of a light-second.
The meter in all its multiples replaces all other units of measurement, long and short. Long distance is measured in the meter multiplied by a thousand—the kilometer. Short distances are measured in centimeters—or millimeters, or micrometers, or however small one needs to measure them.
The meter in all its multiples replaces all other units of measurement, long and short. Long distance is measured in the meter multiplied by a thousand—the kilometer. Short distances are measured in centimeters—or millimeters, or micrometers, or however small one needs to measure them.