what is the metric SI unit used for measuring lengths
https://www.nist.gov/pml/weights-and-measures/si-units-length
The metric SI unit used for measuring lengths is the meter (m). To understand how this unit is derived, let's start with the prefix "meter" which comes from the Greek word "metron" meaning "measure".
The meter is defined as the distance that light travels in a vacuum in 1/299,792,458 of a second. This definition provides an accurate and universal standard for measuring lengths. Therefore, the meter is a fundamental unit in the International System of Units (SI).
To measure lengths using the meter, various prefixes can be added to indicate larger or smaller quantities. For example:
- Kilometer (km): 1 km equals 1,000 meters
- Centimeter (cm): 1 cm equals 0.01 meters
- Millimeter (mm): 1 mm equals 0.001 meters
These prefixes make it convenient to express lengths ranging from large distances (like kilometers) to very small measurements (like millimeters).