The foot equals 30.48 centimeters exactly and is one of the oldest length units in human history. It is the international aviation standard for altitude โ commercial airliners cruise at 35,000 feet. In the US, building dimensions, human height and elevation are all expressed in feet. 1 foot = 12 inches.
Real-world: Airliners cruise at 35,000 ft (10.7 km). Mount Everest is 29,032 ft (8,849 m). A standard US ceiling is 8 ft (2.44 m).
Read full foot reference โThe nanometer equals one billionth of a meter. Visible light spans 380โ700 nm. Modern semiconductors are manufactured on 3โ5 nm process nodes. Gold atom diameter is 0.29 nm. The nanometre is the natural scale for atomic physics and nano-engineering.
Real-world: Visible light is 380โ700 nm. Apple's A17 Pro chip uses a 3 nm process. The DNA double helix is 2 nm wide.
Read full nanometer reference โ