Dear John and All, Hear! hear!
Regards, Pat Naughtin CAMS Geelong, Australia on 2002-07-14 02.03, kilopascal at [EMAIL PROTECTED] wrote: > 2002-07-13 > > Jim, > > I'm going to disagree with you for the following reasons: > > Will the Authorities on SI ever recognise these other expressions as "energy > units" or just equivalence's to the joule? It is the coherency that you > mention that allows us to recombine different units to equate to the joule, > but that doesn't take away from the joule its position as the sole energy > unit in SI. > > By your argument, I can say that length can be expressed in the unit of > joules per newton, or newton seconds squared per kilogram, etc. Even though > one can express length this way I don't think it could or would take away > the uniqueness of the metre as the sole SI unit of length. The same is true > for the joule. > > The hour not only is not a coherent unit with SI, it isn't even an SI unit. > A unit such as the hour, that may have a special status (accepted) for use > with SI, does not make it an SI unit. The resultant combination of an SI > unit with a non-SI unit is still a non-SI unit. By your logic, we should > accept the FFU as a part of SI because they can be combined with SI (farads > per foot, grams per mile, watts per square inch, etc.). Of course, like the > hour they would not be coherent and would relate with an odd conversion > factor. > > I don't think so! > > John > > > > > ----- Original Message ----- > From: "James R. Frysinger" <[EMAIL PROTECTED]> > To: "U.S. Metric Association" <[EMAIL PROTECTED]> > Cc: "U.S. Metric Association" <[EMAIL PROTECTED]> > Sent: Saturday, 2002-07-13 11:17 > Subject: [USMA:21025] Re: Fwd: Energy unit TWH > > >> kilopascal wrote: >>> >>> 2002-07-13 >>> >>> The terawatt-hour is not an SI unit. There is only one SI energy unit, > the >>> joule. The terawatt-hour is a combination of an SI unit, the watt and > the >>> non-SI time unit, the hour. >>> >>> The watt-hour is a unit accepted with limited use along with SI, but it > in >>> itself is not SI. >> .... >> >> John, >> >> I have to disagree with you here. The joule is a specially named derived >> unit provided for energy. But other derived units, without special >> names, can be and are used to express quantities of energy, such as the >> newton meter, the watt second, the pascal cubic meter, and so on. >> >> Marvelously, due to the coherence of the system, the numerical factor >> that relates each item in that short list above to the joule is "1". >> Since the hour is accepted for use with the SI, the watt hour can be >> used to represent quantities of energy, but since the hour is not a >> coherent unit within the SI, the conversion factor is >> 1 W.h = 3.6 kJ >> with the period on the line in W.h representing the raised dot for >> multiplication. >> >> Jim >> >> -- >> Metric Methods(SM) "Don't be late to metricate!" >> James R. Frysinger, LCAMS http://www.metricmethods.com/ >> 10 Captiva Row e-mail: [EMAIL PROTECTED] >> Charleston, SC 29407 phone: 843.225.6789 >> >> >
