Re:International System of Units overhauled in historic vote
by aengvs on Saturday November 17, 2018 @12:14AM
(#18474083)
>No, I represent a quarter as 25/100's to show how it would be accurately represented in metric. 1/4 meter is not pure metric, it's applying a non-metric modifuer to a metric amount. The metric representation of 1/4 meters is 25 centimeters, which is 25/100.
What? Fractions aren't exclusive to the imperial system.
1/4 of a metre is metric, just as a 1/4 of an inch is imperial.
Everything below is a perfectly legitimate way of writing metric units:
1/4 m = 6/24 m = 3/12 m = 0.25 m = 25 cm = 250 mm
So easy!
Re:International System of Units overhauled in historic vote
by kbenson on Saturday November 17, 2018 @02:36PM
(#18476972)
Fractions are mathematical modifiers that can applied to any quantifiable measurement. That said, I imagine they aren't generally used in professional context in metric, because they generally aren't in imperial either. You don't see architectural plans that say 1-1/2 feet, they say 1'-6". Is it common to see fractional amounts in metric when used in a professional context?
Re:International System of Units overhauled in historic vote
by Moru on Saturday November 17, 2018 @05:28PM
(#18477694)
Usually we write everything in mm for professional context.
Re:International System of Units overhauled in historic vote
by kbenson on Saturday November 17, 2018 @05:53PM
(#18477810)
Thanks, that's what I assumed (because it makes sense). For metric you often go two orders of magnitude smaller, but I'm thinking a good amount of the reason to usually go straight to millimeters instead of also using decimeters is that decimeters just can't easily represent many common fractions of a meter (1/4, 3/4, 1/3, 2/3), and a base 10 system can never represent some of those perfectly without resorting to a mixed format.
Actually, I said "It cannot perfectly represent the amount (1/3)", so I specifically game an example immediately after the statement of exactly what I was talking about, which you then ignored and used an example for a different item to represent erroneously. What's up with that?
> You represent a quarter as the fraction 25/100ths to show how impractical it is, instead of writing 1/4.
No, I represent a quarter as 25/100's to show how it would be accurately represented in metric. 1/4 meter is not pure metric, it's applying a non-metric modifuer to a metric amount. The metric representation of 1/4 meters is 25 centimeters, which is 25/100.
Let me lay it out side by side:
- 1 and 1/2 units Imperial: 1 foot 6 inches or 18 inches Metric: 1 meter 50 centimeters or 15 decimeters or 150 centimeters
- 1 and 1/3 units Imperial: 1 foot four inches or 16 inches Metric: 1 meter 33 centimetersa and 3 millimeters and... or 133.33... centimeters
- 1 and 1/4 units Imperial: 1 foot 3 inches or 15 inches. Metric: 1 meter 25 centimeters or 125 centimeters
That's not to say imperial units are good. They are hard to use for most things because they change across types of things measures, and counting in twelfths when needed is much more painful than in tenths.
But, if we were taught in a 12 base system we would be able to use it easily, and base 12 has more cases where it can be used easily than base 10. Everything else would be the same except than our sense of scale would be a little different and we would have an easier tome subdividing things in many cases.
Metric isn't an optimal system, it's just the optimal system for right now and the world we currently live in. But for a few historical turns of fate, it might have been very different.
> Would it be so hard to build a ruler with thirds measured on it, so you don't need to try and guess 0.333333 from mm readings? Like http://teaching.monster.com/nfs/teaching/attachment_images/0.... but made of metal
Then it's not metric. That's the point. We use these values anyway, yet you have to step outside the metric system to represent them easily. Adding extra marks that don't correspond to the regular intervals is confusing, so it's avoided. That's why most rulers in the united states show metric on one side and imperial on the other.[1]
1: http://cdn.dickblick.com/items/554/27/55427-1012-3ww-l.jpg