Length

Length is a measurement that represents the longest dimension of an object, or the distance between two points. It is a fundamental dimension in most measurement systems, including the International System of Units (SI). The SI base unit of length is the metre.

Definition

In geometry, length is the most extended dimension of an object. In the International System of Units (SI), the base unit of length is the metre and is now defined in terms of the speed of light. The centimetre and the kilometre, derived from the metre, are also commonly used units. In U.S. customary units, English or Imperial system of units, distance is measured in inches, feet, yards, and miles.

Measurement

The measurement of length involves the use of a ruler, tape measure, or laser measuring tool. For larger distances, methods such as triangulation or the use of GPS technology can be used. In the physical sciences and engineering, the word "length" is typically associated with "distance", and these two terms are often used interchangeably.

Units of Length

There are many units of length, some of which are used in specific contexts. These include the millimetre, centimetre, metre, and kilometre in the metric system, and the inch, foot, yard, and mile in the imperial system. Other units of length include the astronomical unit (AU), the light-year, and the parsec, which are used in astronomy.

See Also

• Distance
• Metric system
• Imperial system
• International System of Units

Length Resources
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