Rod
A rod is a traditional unit of length used in land measurement and surveying. It is equal to 16.5 feet, 5.5 yards, or exactly 5.0292 meters.
Also known as a pole or perch, the rod dates back to medieval England and was commonly used for measuring land and agricultural plots. It is closely related to other units such as the chain (which is 4 rods) and the furlong (which is 40 rods).
Key conversions:
1 rod = 16.5 feet
1 rod = 5.5 yards
1 rod = 5.0292 meters
4 rods = 1 chain
40 rods = 1 furlong
Though largely replaced by metric units today, the rod is still occasionally used in surveying and legal descriptions of land, especially in the United States and the UK.
Fermi
A fermi is a unit of length used in nuclear physics to measure extremely small distances, such as the size of atomic nuclei. It is equal to 1 femtometer (fm), which is 10⁻¹⁵ meters.
The unit is named after the Italian physicist Enrico Fermi, known for his work in nuclear physics.
Key facts:
1 fermi = 1 femtometer = 10⁻¹⁵ meters
Used to measure nuclear dimensions and particle sizes
Essential in the study of nuclear and particle physics
The fermi is vital for describing distances at the subatomic scale, much smaller than atoms and molecules.