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why is the US not Metric

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KL27x:
Yep. I know the nautical mile as 6075 feet. But it is in fact defined in meters, today, just like all of our units.

If you want to convert into "metric nautical miles" based on 400 grads rather than the 360 degrees used by Euclidian geometry, just multiply by 0.9.

1852m x 0.9 is 1,666.8m. I supposed it should come out to 1,666.6667m, if the earth were a perfect sphere and the French measured it more accurately?

It would appear there is a 3:5 ratio somewhere between the nautical mile and a degree of the surface of the earth?

Edit: 1/60 is 0.01666666666666666667. And there it is. If the 18th century French had respected Euclidian geometry, the meter would not be 3.28084 feet. It would be 3.645 feet. 1,666.667 meters would be a minute of latitude. And a full degree would be 100 km. But they wanted a right angle to be 100 degrees, so a degree of latitude ends up being 111.1111km. Nicely done, France!  :-+

And.... the speed of light would be 269,813,212.2 m/s,

vk6zgo:

--- Quote from: KL27x on January 02, 2020, 09:59:21 pm ---Put that on a tape, and show me. Pics.

Hint: a ruler only goes to like 30 cm and is ok to have fine numbering, even just light etching on a metal ruler. In a 25m+ tape measure, have fun with that idea. If you put cumulative numbers on each cm and did not turn them sideways, it will end up looking like someone writing pi out to the 50 thousandth decimal place.

Show me this metric tape measure that you would use outside, in the field, doing framing with a circular saw, day in day out. Not a ruler for cutting paper at a desk with an exacto knife.

Choosing the size of the meter was a compromise. Belgie didn't put the same priorities on all tasks, esp when he decided there are 400 degrees in a circle.

--- End quote ---


I'm back!-- just for this one time, though.
To hand, I have two tape measures.
One is a 165 ft (50m ) long one, where the numbers restart 1,2, 3----- etc, every 10cm  (100mm) on the Metric side, so are not cumulative. (yes, the people in the PRC who manufactured it made the amazing discovery that tapes have two sides).

On the Imperial side, the numbers restart 1,2,3 ------etc, every foot (12 inches) & are not cumulative.
It would obviously be impossible to use cumulative numbers of inches for a long tape like that one.(how would you fit the last one in, at 1,980 inches ?)

On both sides, the numbers read along the length of the tape, not across.

The other, small tape does use cumulative inches, but is only 10ft long (even so, it is getting a bit crowded at the top end.
On this one, the Metric scale does restart every 100cm.

Even though ISO, & the dear, departed Metrication Board didn't like centimetres, they are about the smallest unit that can easily be numbered, so won a new lease of life, by default.

When I use the big tape, I measure in metres most of the time, then translate them to mm to keep the hardware suppliers happy.

There may have been some "Metric only" tapes sold in Oz, but since they, like most other everyday things are now made in China, & to a lesser extent, India, all the ones I have use both measurement systems.

bsfeechannel:

--- Quote from: SkyMaster on January 02, 2020, 11:53:31 pm ---I feel the need to point out that knot and nautical mile have nothing to do with the US or the Metric system.

The knot and nautical mile are used in aviation (and probably still in use in maritime operation) all over the world, and that work just fine.

The nautical mile is a beautiful unit of measure (for its intended application). The nautical mile is not an arbitrary unit like most imperial units are  ;)

Please, carry on.

 :)

--- End quote ---

The international nautical mile is exactly 1852 km, adopted by the US in 1954. Since the knot is exactly one nautical mile per hour and 1 hour is exactly 3600 seconds, both have everything to do with the metric system.



bsfeechannel:

--- Quote from: unitedatoms on January 02, 2020, 11:43:04 pm ---I wonder if speed of light relationship to meter is involving requirement to have gravity field of earth. There is something time dilation something relativistic there in physics.

--- End quote ---

Of course. All of those factors have to be taken into consideration, depending on the level of precision you want. But the thing is that the metric standard is no longer some physical object deposited in some secluded room in the outskirts of Paris.

SkyMaster:

--- Quote from: bsfeechannel on January 03, 2020, 02:03:20 am ---
--- Quote from: SkyMaster on January 02, 2020, 11:53:31 pm ---I feel the need to point out that knot and nautical mile have nothing to do with the US or the Metric system.

The knot and nautical mile are used in aviation (and probably still in use in maritime operation) all over the world, and that work just fine.

The nautical mile is a beautiful unit of measure (for its intended application). The nautical mile is not an arbitrary unit like most imperial units are  ;)

Please, carry on.

 :)

--- End quote ---

The international nautical mile is exactly 1852 km, adopted by the US in 1954. Since the knot is exactly one nautical mile per hour and 1 hour is exactly 3600 seconds, both have everything to do with the metric system.

(Attachment Link)

--- End quote ---

With all due respect bsfeechannel,

The aviation works in nautical mile. The aviation weather forecast is in knots. The flight planning is done with nautical miles and knots. All the aircraft instruments are in knots and nautical miles. The air traffic control is in nautical miles and knots.

If we fly fast enough and high enough, then we get into the Mach and the Flight Level units.

Please read my post # 985 again  ;)

Why you felt the need to report that in 1954 somebody came up with the meter value representing the nautical miles will remain a mystery.

We pilots, do not give a flying sh*t about the metric value equivalent of the nautical mile.

 :)

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