理解长度测量

长度是两点之间距离的测量。它是科学和日常生活中最基本的测量之一，构成几何学、物理学和无数实际应用的基础。

介绍

Length is one of the seven fundamental SI base quantities and forms the foundation for measuring distance, size, and spatial relationships. It is essential for navigation, construction, manufacturing, and scientific research.

历史

Early length measurements were based on human body parts like the foot, cubit (forearm), and yard (arm span). The meter was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. Today, it is defined by the distance light travels in vacuum in 1/299,792,458 of a second.

关键单位

Meter (m)

The SI base unit of length, defined by the speed of light in vacuum.

Kilometer (km)

Equal to 1,000 meters, commonly used for measuring distances between cities.

Centimeter (cm)

Equal to 0.01 meters, useful for measuring everyday objects.

Millimeter (mm)

Equal to 0.001 meters, used for precise measurements in engineering.

Inch (in)

An imperial unit equal to 2.54 centimeters, still widely used in the United States.

Foot (ft)

Equal to 12 inches or 0.3048 meters.

Mile (mi)

Equal to 5,280 feet or 1.609 kilometers, used for long distances.

应用

  • Construction and architecture for building measurements
  • Manufacturing and quality control for part dimensions
  • Navigation and GPS systems for distance calculation
  • Scientific research and laboratory measurements
  • Textile and clothing industry for sizing
  • Sports field dimensions and athletic performance tracking

Distance Formula

d = √[(x₂-x₁)² + (y₂-y₁)²]

The distance between two points in a plane, where (x₁,y₁) and (x₂,y₂) are the coordinates of the two points.