nautical miles vs kilometers

[Torpedo Magnet]

Just wanted to know the actual historic measurement used and if there is a conversion from one to the other....thanks

[Arlo]

1 nautical mile = 1.852 kilometers

http://www.metric-conversions.org/length/nautical-miles-to-kilometers.htm

[Arlo]

http://en.wikipedia.org/wiki/Nautical_mile

[Daniel Prates]

There is a historic reason for the NM. The fraction of a degree is a "minute", right? So then: a nautical mile is a minute, in the equator (obviously, the higher you go north and south, the lesser a minute of arc will represent in actual space).

Note also that 'knots' are nautical miles per hour.

[Rockin Robbins]

As usual, the metric unit is arbitrary, the English unit has a relationship to the task.

[Gerald]

@Torpedo Magnet! Welcome to SubSim, :sunny:

[Arlo]

As usual, the metric unit is arbitrary, the English unit has a relationship to the task.

I believe the metric unit is very deliberate. It differs in that it's 'relationship' is to other metric units. A yard being the distance from the king's (or king's garment maker's) nose to his extended forefinger may have been handy for that individual, at the time, for that task. Good thing they ended up standardizing it. :)

[Rockin Robbins]

You're confusing "deliberate" with "appropriate to the use for which it is put." An arbitrarily picked number of wavelengths of a certain color light is a very deliberate and exactly determined number. But it has no relationship to the size of a human body if you are producing an automobile or a building, no relationship to the size of a degree if you are navigating.

[WernherVonTrapp]

Welcome abroad.:D:salute:

[Arlo]

You're confusing "deliberate" with "appropriate to the use for which it is put." An arbitrarily picked number of wavelengths of a certain color light is a very deliberate and exactly determined number. But it has no relationship to the size of a human body if you are producing an automobile or a building, no relationship to the size of a degree if you are navigating.

The use for which the metric system was designed for is uniformity. Metric doesn't care if you're measuring the distance to the cup on the seventh hole or the weight of your four-wheeled drive truck after driving through the mud. The use for which nautical miles was designed for is specific, making it become less useful for tasks that are likewise specific to a different task.

So forgive me if I present an argument of semantics when I contest the use of 'arbitrary' when it comes to the scientific design of the metric system versus the overall nature of other systems. The nautical mile may have been one spot of genius in a system that actually had more arbitrary elements than you suggest the metric system has. Again ...

http://upload.wikimedia.org/wikipedia/commons/e/e4/Britanski_merki_za_dalzhina_Grinuich_2005.jpg

"The yard derives its name from the word for a straight branch or rod,[4] (http://en.wikipedia.org/wiki/Yard#cite_note-OED-3) although the precise origin of the measure (http://en.wikipedia.org/wiki/Weights_and_measures) is not definitely known. Some believe it derived from the double cubit (http://en.wikipedia.org/wiki/Cubit), or that it originated from cubic measure, others from its near equivalents, like the length of a stride or pace. One postulate was that the yard was derived from the girth (http://en.wikipedia.org/wiki/Girth) of a person's waist, while another claim held that the measure was invented by Henry I of England (http://en.wikipedia.org/wiki/Henry_I_of_England) as being the distance between the tip of his nose and the end of his thumb." (http://en.wikipedia.org/wiki/Yard#cite_note-Green1986-4)

http://en.wikipedia.org/wiki/Yard

Now ... having said that ... I witnessed the failed attempt to convert to the metric system in the U.S. based on the reason of uniformity.

It didn't work because metric sucks. :shucks:

[Daniel Prates]

Ah jeeez, that discussion again. Arlo, you just steped in a landmine. RR is very sensitive about the metric system. :O:

[Rockin Robbins]

Metric doesn't suck. For some things it's as good as any other measurement system. It's main selling point is that all it's units are a power of ten from each other, making calculations easier.

It's reason for being was a political one in revolutionary France in the late 1700s and early 1800s. It was a "democratizing" of weights and measures. They also tried renumbering our years, altering the number of hours in a day and days in a week. People were smart enough to see that part was plain silly.

Mostly we've extracted all the usable things the metric system brought to the table and applied it to physics, astronomy, a lot of fields where its usefulness outweighs its appropriateness for the task because for those tasks ease of calculation really does outweigh the intrinsic usefulness of the measuring system to the task.

The power of ten really are the metric system's weakness too, because the proportions of nature composed of small prime numbers and their multiples. The factors of 2, 3, 4, 6, 8, 12, 16 in the Imperial System are not accidental or inappropriate. They flow from the continual recurrence of these ratios in the world around us.

[Arlo]

Ah jeeez, that discussion again. Arlo, you just steped in a landmine. RR is very sensitive about the metric system. :O:

I quite like RR's take on anything technical. I anticipate an illuminating experience. Even if I am a born obstinate argumentative sort. :DL

[Arlo]

Metric doesn't suck. For some things it's as good as any other measurement system. It's main selling point is that all it's units are a power of ten from each other, making calculations easier.

It's reason for being was a political one in revolutionary France in the late 1700s and early 1800s. It was a "democratizing" of weights and measures. They also tried renumbering our years, altering the number of hours in a day and days in a week. People were smart enough to see that part was plain silly.

Mostly we've extracted all the usable things the metric system brought to the table and applied it to physics, astronomy, a lot of fields where its usefulness outweighs its appropriateness for the task because for those tasks ease of calculation really does outweigh the intrinsic usefulness of the measuring system to the task.

The power of ten really are the metric system's weakness too, because the proportions of nature composed of small prime numbers and their multiples. The factors of 2, 3, 4, 6, 8, 12, 16 in the Imperial System are not accidental or inappropriate. They flow from the continual recurrence of these ratios in the world around us.

Case in point. :DL

[Daniel Prates]

Yeah, RR, i do not diminish your point, indeed some imperial measurements (not all of them) have relevant ratios proportional to nature, or simply, area easier to use in some situations. The main problem with it is it's lack of UNIVERSALITY, which hampers science and economical advances (i should assume more in the latter that in the first case: can't a scientist simply convert units? :06:). Or at least, that's the classical aproach to the problem.

I'm going to leave you guys with a quote from Willima Kevin - yes, THE KEVIN we all study in physics - that expresses the standard point-of-view from any scientist's part:

"You, in this country [the USA], are subjected to the British insularity in weights and measures; you use the foot, inch and yard. I am obliged to use that system, but must apologize to you for doing so, because it is so inconvenient, and I hope Americans will do everything in their power to introduce the French metrical system. ... I look upon our English system as a wickedly, brain-destroying system of bondage under which we suffer. The reason why we continue to use it, is the imaginary difficulty of making a change, and nothing else; but I do not think in America that any such difficulty should stand in the way of adopting so splendidly useful a reform."

Now, of course, that does not mean that for navigation reasons, the same applies. But that is only for traditions's sake, I would imagine, since the trained expert feels no difference between traveling at 200km/h or 360kts, if he knows his stuff. In fact, in the first decades of aviation, it was not clear which system would be eventually adopted internationally, and several leading countries in aviation would use the metrical system - germany, for instance, as well as russia was still using it by the end of the cold war. But, since those countries (or their governments of them'old days, to be more correct) were draged to the trashcan of history, they all eventually tended to adopt the victorious side's standards. It could have been different, and within a generation or two, nobody would feel the difference.

[Daniel Prates]

Metric doesn't suck. For some things it's as good as any other measurement system. It's main selling point is that all it's units are a power of ten from each other, making calculations easier.



Oh and BTW... that's not it. Metrical is superior as you can directly link all measurements of all areas of science into one, single, coherent and internally-related universal system.

Metric does not limit itself to the "meter = distance" basic unit. In fact, just in an example, you have this: 10 cubic centimiters equals one liter which equals one kilogram. So, let's start figuring out. From mass, you also deduct force. From space versus weight you also deduct density. And so on and so forth, in such a manner that eventyally all modern significant areas of science - electricity, calories, even quantum mechanics - they all depend on metrical relations to be coherent between each other.

Something hard to do when you convert inches to joules to calories to newtons to... anyway, you get the point.

The proof of that is that imperial stopts making sense in some more modern scientific issues - heat, force etc - and you suddenly see yourself forced to use metrical system along imperial system, as imperial does not provide it's own answer.

[Rockin Robbins]

uhhhhhh.... I think I said that.:D The metric system copied parts of the Imperial system, in that a volumetric ounce of water weighs an ounce, and there are other relationships between units. Density, force, electricity and the meaning of the universe were all calculated in other units, imperial being one, long before the metric system was a glimmer in some French revolutionary's eye.

Even pretty advanced mathematics was done with roman numerals before the arabic numbering system came to be used in the west. The people who actually lived with the roman numeral system used it very differently than we are taught in school. We are taught roman numerals with the purpose of teaching us how stupid they were. Therefore no effort is spent in teaching us how they could be used. Having a copy of the original 1611 King James Bible, guaranteed to make you curse and all the roman numerals infesting the thing, also shows how ingenious they were in making it easy to read and use them. Hint: had you done that on a test in school they would have had lots of fun marking things wrong. It's a typical case of a later culture's necessity of portraying an earlier one as less intelligent, less imaginative, less capable than our own. That's a lie. We are no better than any other randomly sampled group of human beings who have populated the planet. People are people, with the same range of individual potentials, regardless of culture or time.

Even in the metric system there are absurdities, such as something at 40º C is not twice as warm as something at 20º C. That's where the Kelvin scale came from, to resolve that problem. Every scale has a reference point, and the Celsius scale chose the freezing and boiling points of water. As it turned out, there was usefulness to that and usefulness has to be done away with in a world of science.:har: Actually, science chooses measurements for characteristics that are useful to scientists, not to the general public. But you can see how tricky choosing units can be.

There's nothing sacred about the imperial or metric system. By measuring things built, it is somewhat easy to determine the units they used because measurements of things built tend to come out even. By measuring Mayan ruins, archaeologists have been able to determine what their basic measurement units were and to be able to reproduce their size.

With the imperial system it would be child's play on a small scale. Just use the dimensions of bathroom tiles and you'll fine 1, 2, 3, 4, all the way up to 12" tiles and even larger. But with a large sample, it will be simple to find that they are all composed of multiples of the smallest unit normally used for that application: the inch. And you could tell exactly how large an inch was. Similarly, if you found some metric tiles in your research you could easily toss them out of the sample group by determining that their dimensions were not multiples of the imperial group.

Hopefully, a curious archaeologist would put them all together and determine the size of metric units.

[Daniel Prates]

Even in the metric system there are absurdities, such as something at 40º C is not twice as warm as something at 20º C. That's where the Kelvin scale came from, to resolve that problem.

Indeed, centigrades exists from an arbitral choosing of freezing and boiling of water being equal to 100 and zero, just because Anders Celsius thouhg that it sounded about right... but fahnrenheit is also arbitrary on it's own premisses. I think that the kevin scale was conceived so that there could be an absolute zero which indeed measured 'zero', which is a bit less arbitrary, I guess.

Still, 99.9999999999% of scientists, from the past 100 or 150 years, have been pointing out the inadequacy of imperial units. Concerning everything. don't get me wrong RR, I don't mean to be a bore, but most people who stand by the imperial system, do so for reasons of attachment or taste or other subjective reason. It seems to be a cultural issue. Mayans used a vintesimal system, where everything came down to twenty. Who knows why the hell they adopted that... They also used a bunch of tied-up strings to make calculations, something like an abbacus, which still today we cannot understand how it works... what I'm trying to say is that the 'pros' of the imperial system might - just might - be apparent, and as Kevin said below, come more from the illusional difficulties of a change, than from actual, reasonable reasons.