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why is the US not Metric

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TimFox:

--- Quote from: unitedatoms on January 03, 2020, 03:36:45 pm ---How lucky the humanity is by having electrical quantities in sensible units. Amperes, Farads, Volts, Ohms, Henries, etc. Except may be magnetics, with Webers and Teslas and who knows what. Imagine conversion from Sumerian Volts to Imperial Electrical Tension units. Oh and those Nepers (had to learn it recently).

--- End quote ---
Webers (Volt-second) and Teslas (W/m2) are perfectly sensible units in the same SI system as A, F, V, C, ohms, H, etc.
Things get unsensible when you mix cm and Gauss into magnetic calculations, where you have to change the fundamental equations.

unitedatoms:
Yes the either Gauss or Tesla is redundant and confusing, do not remember well. And one of the reason I may not remember it well is that original confusion, when one learns and gets units introduced. On a subtle level the math involving retarded units break the will to think and learn. I believe the mechanical engineers insisting on imperial units suffer small daily loss of IQ from unnecessary fatique. 

TimFox:
In electrodynamics, there is a “retarded potential” due to the finite speed of light, but the units are either “rationalized” (as are the SI units) or “unrationalized” depending on where you put 4 pi into the equations.  For electronics, I recommend sticking with rationalized SI units.

Zero999:

--- Quote from: KL27x on January 02, 2020, 12:13:29 am ---That's funny, because in metric, the unit sizes make jumps by 10x, rather than 2x when dividing an inch into 2^-1 fractions. So if you like to use some unit that is say, about 3x as big as a centimeter, you might as well use the word inch. If you wanted something about a third the length of a meter, you might as well use a foot. Since they are already well defined. Esp if your country, which is the size of the entire EU, already uses them, consistently, as is the case for the US.
--- End quote ---
The same could be said about any unit. My little finger is about 1cm wide, so it's more convenient than inches and the distance between my finger tips and opposite shoulder is closer to a metre, than a yard, which comes in handy for measuring lengths of cable.


--- Quote ---Interesting thought I discovered out of this thread. Of the native english speaking world, the US, alone, counts for near 3/4 of that figure. 2 billion people speak English. 400 million speak it as their first or lone language. About 300 million of these folks live in the US. The majority of english speakers around the world perhaps don't have much exposure to imperial units other than through media. Living in it is a different perspective, and it isn't even a thing to notice. Metric is just as useful to Americans, even if we don't feel an urgent need to buy butter in grams or to drive in km/h.
--- End quote ---
The beauty of SI units is they're independent of language. 1l of water is the same the world over: 1000cm3. The same isn't true for pints and gallons.


--- Quote ---^ It would appear that someone in France wanted to make everything into 10's and 100's.

If that had caught on, we would be making right angles of 100 degrees/grads (a hectodegree?). Triangles would have 200 degrees/grads. Circles and polygons would add up to 400 degrees/grads.

A 45 degree angle would be 50. Considering the ubiquity of 30 and 60 degree angles in design and engineering and construction, these would now be 33.333 and 66.667 degrees.

An about-face or complete change in viewpoint/stance would be doing "a 200."   :-DD 
In this base ten utopia, "K" and "100" could be applied and used to mean every other thing imaginable.

--- End quote ---
Well most scientific calculators have the option to enter degrees in gradians, although I've not used them myself.


--- Quote ---Centimeters. Made by man in order to divide a circle into 400 degree. And so we can have these beauties:
https://www.123rf.com/photo_97469762_yellow-metric-measuring-tape-isolated-on-white-background.html

So if you are ok with stopping short on the grand Belgian plan and leaving 360 degrees in a circle, that's kinda how Americans feel about changing road signs and our daily parlance to metric. Yeah, that sounds nice. Just not for us.

--- End quote ---

The arguments for measuring angles in powers of 10, aren't as strong as distance, mass etc. because angles are really a fraction of a circle. The base unit is the turn, rather than a degree, which is 1/360 turns. We could divide a circle up into any arbitrary number, 360, 400, 24, 1024 etc. There's not so much of an advantage of multiplying by ten, as there is with other units of measurement. For example 1/8 turns is 50 gradians or 45 degrees: I don't see how either of those systems is easier to use than the other. 360 was probably chosen because it's possible to divide it by many different numbers, without going into decimals. Turns are often used for encoders, with the output being a binary fraction from 0 to nearly 1, so 10-bits would give 0 to 1023/1024. I'd probably chose turns or milliturns, if I had to pick a unit for angles, but degrees are the most common.

KL27x:

--- Quote from: Zero999 on January 04, 2020, 11:57:47 pm ---
--- Quote from: KL27x on January 02, 2020, 12:13:29 am ---That's funny, because in metric, the unit sizes make jumps by 10x, rather than 2x when dividing an inch into 2^-1 fractions. So if you like to use some unit that is say, about 3x as big as a centimeter, you might as well use the word inch. If you wanted something about a third the length of a meter, you might as well use a foot. Since they are already well defined. Esp if your country, which is the size of the entire EU, already uses them, consistently, as is the case for the US.
--- End quote ---
The same could be said about any unit.
--- End quote ---

Not exactly. We really only have practical metric prefixes for every 3rd order of magnitude. The "short prefixes" of deci/deka/centi/hecto only work around a single base unit of meter and liter for distance and volume. Regarding mass, you have two base units being gram and tonne, which provides an additional nucleus for the short prefixes. You can have a dekagram. And you can have a dekatonne.

In imperial, you can apply these prefixes to inches, feet, yards, miles. That's all distance, and it doesn't even include furlongs and perches, yet, lol. In mass, you have  oz's or grains or lbs or short tons or long tons. In volume, you have ozs, cups, pints, gallons, barrels. Using centi/hekto/deka/deci with each of these units will produce a new range that might be useful for different things. In metric, you will have some gigantic gaps. 

Worse, as I showed earlier, the tools and/or industry standards can't always deal with these different prefixes. So you will use what you have. If your scale or caliper only displays in certain units, then that's what you choose from. Sometimes grams might be better. Sometimes grains. Sometimes milligrams. Depends what you are doing. No matter what you know in your head, the way you work will be affected by your available options when it comes to tools and standards.

Given all this, why are you so gungho about eradicating options other than metric?


--- Quote ---My little finger is about 1cm wide, so it's more convenient than inches and the distance between my finger tips and opposite shoulder is closer to a metre, than a yard, which comes in handy for measuring lengths of cable.
--- End quote ---

Hence, where that is useful to you, you should use those units. There are some places where certain units might be useful due to the size of the units. There are places where units are useful due to legacy issues. And there are places where certain units are useful due to body of knowledge/standardization (e.g. how the mole is arbitrarily defined in grams by avagadro's number, and how 1L is standard amount of solvent for solutions). But in America, a lot of this is reversed; USC is still useful for many things, here, due to all 3 of these major reasons in addition to culture. So we use both systems.


--- Quote ---The beauty of SI units is they're independent of language. 1l of water is the same the world over: 1000cm3. The same isn't true for pints and gallons.
--- End quote ---
I agree; this is why we (including Americans) love metric. Aussies use schooners and middys and pots, but this doesn't confuse anyone in Australia. You guys use pints and mph and stones, and no one gets confused over there. The fact we can describe any country/industry/custom unit in "the master system" called metric saves a lot of confusion.


--- Quote --- I'd probably chose turns or milliturns, if I had to pick a unit for angles, but degrees are the most common.
--- End quote ---
"Milliturns" might be sliced bread for specific things. Grads might be great for certain things. But is it worth changing how airplanes navigate in order to switch to milligrees of lattitude and longitude? Is it worth retraining your artillery crew with new dope charts for distance and elevation and wind?* Changing geometry and scientific calculators to use 1000 milligrees for sin and cosine and tangent? To make a right angle 250? Do you have to "choose the best" and then use only one single system for every single function we perform using measurements? You will fix a lot of stuff that isn't broken; and you will introduce new problems just by sheer coincidence of seemingly innocuous differences that manifest in funny ways in specific applications, particularly where humans apply prior knowledge and experience and training. IOW, if the French artillery is hitting what they're supposed to, maybe let them keep using grads.

To many europeans, the answer appears to be a resounding "yes, as long as it's metric," let's just use one system for everything. To me, I rather understand math and ratios and relationships to get w/e I need out of w/e is already working exactly fine the way it is. And wherever human input is a factor, I would create a new unit if and where that helps humans to complete their task, even if the computer program under-the-hood is using metric or milligrees or grads or otherwise.

*I read somewhere that French artillery is done in grads; lest you think I'm obsessed with war or something.

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