"symmetrically placed in the same horizontal plane at a distance of 571 mm from each other"
OK.. If they are using this to define a meter, how do they know how long 571mm is?
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"symmetrically placed in the same horizontal plane at a distance of 571 mm from each other"
OK.. If they are using this to define a meter, how do they know how long 571mm is?
The meter has had numerous base definitions. The earliest I have seen was the distance of the step of a Roman solider.
For an in depth discussion this is a good start.
At some point any measurement unit comes down to an arbitrary choice. Could have used how far the average person could toss a midget. What they're doing is trying to define that arbitrary choice in terms that are a stable/unchangine as possible over a wide range of conditions and time.
People interested in these things have continued to devise at great time and expense devices to standardize measurement. I came across the latest effort to create an evermore accurate device to measure a true kilogram — the Kibble Balance. I must presume there are circumstances in which such ultra-precise measurement becomes necessary but no examples are given in the articles. It is fascinating to me however to observe the ingenuity and dedication that goes into such endeavors though.
This first article set me off —
https://www.newscientist.com/article...on-takes-hold/
...and this second one buffaloed me with the math, but intrigued me with the descriptions of the execution —
https://www.nist.gov/si-redefinition...kibble-balance
Yes, but the formula to transpose is not linear.
T(°F) = T(°C) × 9/5 + 32
or
T(°F) = T(°C) × 1.8 + 32
So, using the formula and TG’s deleted query —
15 x 1.8 = 27 + 32 = 59