Convert Femtometer (fm) to Furlong (fur) instantly.
About these units
Femtometer (fm)
A femtometer, equal to 10⁻¹⁵ meters, is the scale at which the structure of atomic nuclei becomes measurable. Also known historically as a "fermi," this unit is used extensively in nuclear physics to describe the radii of protons, neutrons, and nuclei, which typically span 1–10 femtometers. At this scale, the strong nuclear force dominates interactions, and classical intuition breaks down almost entirely—quantum mechanics provides the only meaningful framework. The femtometer also plays a role in high-energy particle experiments, where the wavelengths of probing particles (like high-velocity electrons) may be expressed in femtometer increments. These small wavelengths allow researchers to resolve sub-nuclear structures. While invisible to any optical instrument, distances in the femtometer range can be inferred through scattering experiments, such as those performed in particle accelerators.
Furlong (fur)
A furlong, equal to 10 chains or 660 feet, originated as the distance a team of oxen could plow before needing rest. Its name derives from "furrow-long," indicating the length of a typical plowed furrow in medieval agriculture. This agricultural basis linked the furlong to the acre: a rectangle one furlong long and one chain wide equaled one acre in area. Today, the furlong is most notably used in horse racing, where race distances are often measured in furlongs rather than miles. This tradition reflects both the unit's historical importance and its suitability for describing moderate distances. While archaic in most contexts, the furlong remains a culturally iconic measure that connects modern sports to medieval agricultural practices.