>Dear All, > >A little while ago there was a discussion here about luge speeds. Some >favored metres per second and others favored kilometres per hour. > >This raises the whole issue of what we are trying to do with metrication. > >Are we trying to introduce SI globally? Included with SI I would include the >concept of only having one unit for each quantity. > >Or are we trying to introduce a mongrel system that is largely SI but also >includes odd units that have different pedigrees. For example the reasons >might include such things as: > >. historical considerations >. special pleading by scientific groups >. arguments about safety by medical groups >. direct political pressure at the whim of powerful politicians > >Think about km/h, L/100km, kWh, etc. > >Cheers, > >Pat Naughtin
We have a well-established mongrel system; it is the measurement of time. That was so well established world-wide that the metric fathers did not dare to touch it. Certainly when driving it is more practical to think in terms of km/h rather than m/s. For fuel consumption L/100 km preferable to, say, m3/Mm. As for electricity consumption kWh is more comprehensible that J, again because we think of time more in terms of hours than seconds. To get a clean system we would need to have 100 000 newseconds in a day, But that would be inconvenient for timing three work shifts in a day. It would also involve new valwes for speed, acceleration, frequency, force, pressure, work, power, electric charge, electromotive force, capacitance, electric resistance, electric conductance, magnetic flux, magnetic flux density, inductance, activity of a radionuclide, kerma, organ equivalent dose, and about 24 other SI derived units. Anyway, you get the idea. Changing the second is not on. The hour is here to stay. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 TEL. 416-486-6071
