| ▲ | nemomarx 21 hours ago | |||||||||||||||||||||||||||||||
isn't a cm now defined based on the distance light travels in a vacuum in a very small period of time? so it's not arbitrary really, or rather it probably goes the other way around. a cm used to be based on an arbitrary physical distance but was I think redefined to avoid needing to keep a standard meter cube in Paris. | ||||||||||||||||||||||||||||||||
| ▲ | hnuser123456 21 hours ago | parent | next [-] | |||||||||||||||||||||||||||||||
It started with the grandfather clock. Everyone's clock pendulum needed to be the same length to have the same length of a second. So a meter also happens to (approximately, this was before we could easily be precise to several decimal places) be the length of pendulum that cycles at 0.5 hz (each swing back and fourth is a second) in 9.8 m/s^2 gravity. | ||||||||||||||||||||||||||||||||
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| ▲ | SiempreViernes 20 hours ago | parent | prev [-] | |||||||||||||||||||||||||||||||
The standard metre was a rod 1 metre long, you might be thinking of the standard kilo which is a compact cylinder? | ||||||||||||||||||||||||||||||||