Femtometer
A femtometer (fm) is a unit of length in the metric system, equal to one-quadrillionth of a meter (1 fm = 10⁻¹⁵ meters). It is also known as a fermi, named after the physicist Enrico Fermi. Femtometers are used to measure extremely small distances at the subatomic level, such as the size of protons, neutrons, and atomic nuclei. For example, the radius of a proton is about 0.84 femtometers. This unit is commonly used in nuclear physics and particle physics, but it's far too small for everyday measurements.
Ken
A ken is a traditional Japanese unit of length used mainly in architecture and construction. It measures the distance between two pillars in traditional Japanese buildings and is roughly equivalent to 6 Japanese feet (shaku) or about 1.82 meters (approximately 6 feet).
The ken was a standard module in Japanese design, influencing room sizes and proportions in temples, houses, and other structures. Its use helped maintain harmony and consistency in traditional building layouts.
Though largely replaced by the metric system today, the ken remains significant in studying traditional Japanese architecture and cultural heritage.
Summary:
1 ken ≈ 1.82 meters (6 feet)
Based on spacing between structural pillars
Used in traditional Japanese architecture
Important for historical and cultural studies
No conversions available for length.