Convert Furlong (US Survey) (fur (US)) to Femtometer (fm) instantly.
About these units
Furlong (US Survey) (fur (US))
The US Survey Furlong is defined as 660 US Survey Feet (~201.168 meters), exactly 10 US survey chains. It was historically used in land measurement, agriculture, and railroads. Furlongs remain relevant for interpreting historical property layouts and land grants, particularly in rural and agricultural contexts. The unit's convenience derives from its direct relationship with the acre and chain, facilitating rapid calculation of large land areas. While the furlong is largely obsolete in modern measurement, it persists in legal and historical survey references, bridging imperial traditions and contemporary land-use documentation.
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.