For clarity (since the article doesn't make it clear), there are two "standard" definitions of the units. Is the inch exactly 2.54 cm [the standard international foot], or is the yard exactly 39.37 cm [the US survey foot]?
These two definitions are off by 2ppm. For all intents and purposes, they are the same. If you measured the distance between San Francisco and New York City, the error in measurement between these two definitions would be between 8 and 9 meters.
Is the inch exactly 2.54 cm [the standard international foot], or is the yard exactly 39.37 cm [the US survey foot]?
Wait...if a yard is 39.37 cm than a foot is 12 1/3 cm, which would make an inch 1 1/36 cm. That's off from 2.54 cm by way more than 2 ppm!
A yard would be exactly 91.44 cm if the inch is 2.54 cm, and something very very close to that if it is 2 ppm from the "inch is 2.54 cm" yard.
Did you copy/paste the wrong thing? A survey foot is 1200/3937 meters (making a yard ~91.44018288 cm), so 3937 would probably be floating around somewhere on any page talking about this.
Comments
For clarity (since the article doesn't make it clear), there are two "standard" definitions of the units. Is the inch exactly 2.54 cm [the standard international foot], or is the yard exactly 39.37 cm [the US survey foot]?
These two definitions are off by 2ppm. For all intents and purposes, they are the same. If you measured the distance between San Francisco and New York City, the error in measurement between these two definitions would be between 8 and 9 meters.
Wait...if a yard is 39.37 cm than a foot is 12 1/3 cm, which would make an inch 1 1/36 cm. That's off from 2.54 cm by way more than 2 ppm!
A yard would be exactly 91.44 cm if the inch is 2.54 cm, and something very very close to that if it is 2 ppm from the "inch is 2.54 cm" yard.
Did you copy/paste the wrong thing? A survey foot is 1200/3937 meters (making a yard ~91.44018288 cm), so 3937 would probably be floating around somewhere on any page talking about this.
You're right--it should have been a meter is exactly 39.37 inches.