Originally posted by russ_watters
Maybe I shouldn't bring this back, but this part seems to be the main sticking point. HERE is a website I often use. It lists the SI units as:
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Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature kelvin K
Amount of substance mole mol
Luminous intensity candela cd
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Judging by the responses of others, I'm not the only one who uses only these units for SI (except Newtons: strange it isn't listed, but I guess its not fundamental, but a derivation from f=ma). I quite frankly don't see the point of a kg-f, and have never heard of it before this thread - meaning though it exists, its not commonly used and may be obsolete, just like all those English units that have been recently discarded.
Units and measurement systems exist to be used. In actual use SI/metric is far simpler than the English system. Yes, that's an opinion, but its an opinion clearly shared by a lot of people. And the way I use these units I learned in two different, respectable American universities.
Quite frankly, I think your membership in the "Dozenal Society" gives you a very different perspective on units than the vast majority of other people haave.
I would be interested in learning more about these units though. Can you give me some examples of where, why, or how people would use a kg-f or a poundal?
edit: I found THIS on Wikkopedia:
Just for the record (English system):
Length Foot ft
Mass Pound lb
Time second s
Electric current --No units (other than metrical ones)--
Temperature Rankine R
Amount of substance Poundmole lbmol
Luminous intensity candle
Anyway, on to your message...
As far as I am concerned, 'obsolete', just like 'arbitrary', is a word that seem to be bandied about in these kind of debates without any real thought. I would say that, as in many engineering fields, the kilogramme-force and the pound-force are preferred over the Newton and poundal. This results in often being required to use the TMe/hyl and slug.
The problem essentially arises as there is an awkward relationship between thebasic units both in metrical systems and English ones (i.e. the acceleration of gravity is not great). Thus, we end up with the above situation.
I would say that the Newton and kilogramme ARE more often used than the english equivalent of Pound and poundal, but that is merely because English does not have the vast network of officaldom's support behind as SI does. It is because of this that the slug-pound-poundforce situation is more of an "issue" when using english units than when using metric SI; people simply use what is most practical (given issues raised by g's figure in these systems of ours) without being given advice on which units are 'preffered' as is the case in SI.
Back on to 'obsolete', though- I would say that units still used and serving a purpose, are far from 'obsolete'. I certainly shouldn't like to tell all of those english and metric engineers that their units, and probably they themselves, are 'obsolete'.
As for my membership of the dozenal association, I shall clarify. Dozenalists are a diverse bunch- like any group of people. Some dozenalists believe the only way forward is to adopt a base-12 counting system and have a system of weights and measures where the units are related totally by the factor 12 and its squares, cubes etc. However, some other dozenalists just believe that the number 12 should play a large part in present systems of W&M within the context of a base-10 numeral system. I am more the latter than the former.
Bearing this acceptance of mine of the base-10 counting system that we all use, and also keeping in mind the issues (touched on above) relating to g as a troublesome pseudo-constant, I have devised some alternative systems of W&M.
Given we are working within a base-10 counting system, the factors of much use are 10, 100, 1000 etc, and 2 and 5. Thus I bring you to the core of three alternative systems- one metric-slanted (in a way), and two English slanted.
Inch-Pound_Trice
This system was designed by Andrew Usher and Leonard Cottrell. I shall link you to a page on the units system.
IPT
Foot-Pound-Quarter
By use of a unit of time- I call the 'quarter [second]'- equal to EXACTLY 0.25 seconds, we have reduced g to 2.010878 feet per quarter squared. Far more manageable and useful than the English 32.17405ft/s/s or the SI 9.80665m/s/s
The corresponding force unit is equal to 0.497 pounds of force. This unit is called the mark (from the many 8oz / half-pound units historically widespread on the European continent and in Britain)
Alen-Mark-Quarter: a variant system
This systems introduces a metric-style equivelance 'tween mass, capacity and volume units (1 CC = 1ml = 1g)
This is due to make a length of EXACTLY 2ft become the length unit (the alen: from the 24" units of europe of this name, related to the 'ell'). The mass of a volume of 1 cubic alen of water is now equal to 500 pounds.. or 1000 marks (hence the change in mass unit)
Obviously, due to a length unit equal to exactly 2 ft, g is now effectively taken out of the equation, with g accelerating at 1.005439alens per quarter squared (at 45 degrees sea level)
****** The advantage of both of these systems is that they fix some fundamental and frankly embarressing problems with English- one of which is shared with metric- and are completely usable i nthe context of a nation using the Traditional English units (due to exact conversion between marks and pounds, alens and feet, quarters and seconds (2:1, 1:2, 4:1 respectively)
New Metric- based on the decimal time system
The reason the metre is its length is due to it being based on a fraction of the Earth's ciorcumference by way of the centesimal system of angular measurement (1 right angle = 100 grads)
This system was shortly abandoned (along with the corresponding decimal time), and so thus the metre became irrelevant.
However, this system looks as if it may make a return after being repackaged by swatch as "internet time", with 1 "metric second"- the "blink"- being equal to 0.864 secs (1/100,000 days).
In such a system g = 288.2"
My variant comes from the view that the Earth's circumference is no longer relevant (and never really was), so that making g = a sensible number (either 1, 10, 100, 1000... or 2) is of primary importance. I say that g is 10 "metres" per "blink" squared.
This results in the following:
New Metre (I call it 'arshin')= 28.82"
New Kilogramme (I call it 'funte')= 13.84oz
New Newton (I call it 'tael')= 1.384ozf
[the names are fro mthe Russian and East Asians units of similar sizes]
Cheers, I hope this has been of interest.
