Posted by John on January 08, 2000 at 13:48:44:
In Reply to: Re: slugs posted by Scott Johnson on January 07, 2000 at 01:04:31:
> All of these units are derived units except amperes. They can be
> expressed in basic units. The amperes is not really metric or English,
> but is claimed by both systems (the same for seconds, moles, and
> candelas).
The Ampere is metric or SI. It is defined as an SI unit. Ampere never was an English unit. Ampere is now defined as the current in two parallel conductors, of negligable cross section, seperated by 1 m of free space, and of infinite length, that will produce a force of 200 nN between the conductors for each metre of length. No way can Ampere be considered an English unit.
It is an SI unit used with English since English does not have a current unit of its own. Just like kindergarten is a German word used in English, because no English word exists to convey the concept. Using kindergarten in English does not make it an English word.
> > When using these units, one is using SI, especially when one uses the
> > proper prefix attachments, even if one isn't aware of it. So, to say
> > English is as complete as SI is a big oversight.
> I did not say this. We are talking English and metric system not SI.
> SI and metric are not equivalent (though the SI system does use
> the metric system).
SI is metric and metric is SI. SI is the official symbol and metric is the common name. Yes, SI came into existence in 1960 and before that there was MKSA and cgs, all called metric. But, when SI was born, the rest were officially deprecated. Even so, a metre is the same in SI, in MKSA and cgs, as are all other units. I can go on and on, but I think you got the point.
> Maybe I should rephrase my statement. The English system is as
> complete as the metric system (not a complete system under your
> definitions). Both the English system and metric system define
> basic units, not derived units. Other systems are left to define
> the derived units.
> The metric system defines the kilogram and the meter, that's it.
> The rest of the basic units do not necessarily belong to English
> or metric or any other system. They've been adopted by both systems.
> SI units are a standardization that happens to be based on the original
> metric system.
I don't think English seperates base from derived. I've never seen it done. If you can do it, show me how it is done.
SI, defines 7 base units: length (metre, m), mass (kilogram, kg), time (second, s), Thermodynamic Temperature (kelvin, K), electric current (ampere ,A), luminous intensity (candela, cd), and quantity of matter (mole, mol).
The rest are derived units. Derived units may be defined from base units, like velocity (metres per second, m/s), other derived units, like voltage (volt = joule per coloumb, J/C), or a combination of derived and base units, like power(watt = joule per second, J/s).
So, your statement above is wrong.
> > BTW, English is not a recognized system. In order for it to be
> > considered a system, it must be consistant and coherent.
> > The CGPM and BIPM only recognizes SI as a system, as it is
> > the only "collection of units" fitting the definition of
> > what a measuring system is. Even the US government goes
> > along with the CGPM and BIPM decision, by calling the
> > English hodgepodge as: US Customary Units.
> The English system is consistent and coherent.
No it isn't. A coherent system has only one unit used to measure a physical property. For example in SI, there is only the metre to measure length. English has inch, foot, yard, mile, etc. All seperate and non-related units, except for conversion factors. SI scales by use of prefixes, but a prefixed unit is not distinct like units in English are. 123 mm is the same as 123 x 10^-3 m. The 123 stays intact when going from millimetres to metres. There is no conversion involved as there is when going, for instance from feet to yards. 12 feet is 4 yards. 12 is not 4. I could go further, but I think you got the point.
A consistant system requires that a unit name can not be duplicated and have alternate uses. A kilogram is a unit of mass. But, an ounce can be a unit of mass, a unit of weight, and a unit of volume. Then an ounce can be avoirdupois or troy. In each case the values of the ounce vary.
For these reasons, the BIPM does not consider English a system.
> Of course the CGPM "recognizes" SI as a system - they created the
> SI system. They are not an organization that recognizes measurement
> systems, they define measurement systems (in coordination with
> laboratories through out the world - including the US). They are the creators
> and maintainers of the SI system. The BIPM is under the CGPM.
Neither the CGPM or the BIPM invented metric. The French Acadamy of Sciences did during the time of the French revolution. The BIPM and the CGPM came about as a result of the Convention du metre in 1875, to assure the continued perfection and stability of metric (now SI), as well as to add add define units, etc.
> You give the false impression that they are some sort of independent organizations
> that decide what systems to be recognized or not. This is not the case.
OK! The BIPM is the International Bureau of Weights and Measures, and the CGPM is the General Conference of Weights and Measures. The CGPM is a part of the BIPM.
In addition, international industrial organizations do not recognize English as a legitimate system. They are the ISO, and IEC, just to name two. All of their standards are SI based. American standards organizations wanting to be recognized as having international appeal, are now in the process of adopting their standards to rational SI in order to accepted by ISO and IEC.
> You are right the US government goes along with the CGPM because
> they with other industrial nations signed the international treaty establishing the organization.
Which means they agree that English is not a system.