>"Michael Alexander" <malex@bigfoot.com> writes:
>>While reading the latest edition of "Network Rail", I noticed that they
>>seem to have adopted the incorrect "kph" as their standard abbreviation for
>>kilometres per hour.
>>Apart from giving them less credibility than they deserve, does this annoy
>>anybody else, or is it just me? It seems that we are being flooded by kph,
>>kmh and even abberations like kmp/hr, while the simple (& correct) km/h is
>>becoming a rarity.
>No, it's not just you. Metric things have taken over pretty well in
>this country, but there are a few old imperial constructions that
>people find it hard to give up. They seem to me to be psi, mpg and mph.
>Few people use kPa, none at all use L/100 km, and kph reminds them of mph.
>The best I saw, at a tramstop, was a painted speed limit for the tram -
>20 k/mh. Well, they tried!
>>And of course, the pronunciation of kilometres as "k'lommiters" is even
>>worse. You almost get strange looks these days if you pronounce it
>>correctly!
>Sorry, you (and I) are pissing into the wind with this one! People think
>it's correct (thermometer, barometer, speedometer etc. etc.) and are
>amazed when you suggest that kilometres, not being measuring instruments,
>are not pronounced as them. Maybe we could ask them to pronounce
>kilogram, kilopascal, kilojoule, kilonewton, kilowatt etc, followed up by
>pronouncing mill-IM-etre, cen-TIM-etre, and see what happens. But I think
>we have to give up - we don't want to look obsessive, do we!
>Regards,
>David.
Coherent systems of units
The base SI units, the derived SI units, and the supplementary units
together form a coherent system of units in which the derived units
obtained from the base units are expressed in algebraic form by making
use of the signs for multiplication and division and of powers.
The International Bureau of Weights and Measures has published a
comprehensive document that describes the origins of the International
System of Units, based on decisions of the General Conference on
Weights and Measures and the International Committee for Weights and
Measures, the practical application of the System, and the methods by
which the most important units are realized at the principal national
metrological institutes.
Decimal multiples and submultiples of SI units
For the purpose of creating a limited series of decimal multiples and
submultiples of SI units, several General Conferences on Weights and
Measures, the 1lth (1960, Resolution 12), the 12th (1964, Resolution
8), and the 15th (1975, Resolution 10), adopted the following SI
prefixes and symbols:
exa (E) for 10^18 deci (d) for 10^-1
peta (P) for 10^15 centi (c) for 10^-2
tera (T) for 10^12 milli (m) for 10^-3
giga (G) for 10^9 micro (u) for 10^-6
mega (M)for 10^61 nano (n) for 10^-9
kilo (k) for 10^3 pico (p) for 10^-12
hecto (h) for 10^2 femto (f) for 10^-15
deca (da)for 10^1 atto (a) for 10^-18
There are a couple of new ones introduced in 1996 or 97 for 10^+21 and
10^-21, but I have mislaid the reference to them. You can see that
the abbreviated prefixes are not totally consistent, mixing and
matching upper and lower case, also one and two-letter prefixes
When it is necessary to distinguish between the coherent totality of
the SI units and the decimal multiples and submultiples bearing the SI
prefixes, the latter units are referred to simply as decimal multiples
and subniultiples of SI unitS6.
The SI prefixes can of course also be used for forming the
corresponding decimal multiples and submultiples of units not
belonging to the coherent system of 51 units.
Prefixes indicate powers of 1000. When stating the numerical value of
a measurement, a prefix should be selected which will give a value for
the measurement between 0.1 and 1000 eg. 1234 litres should be 1.234
kilolitres.
Multiples of the unit of mass are formed with the unit "gram" instead
of the base unit "kilogram".
The tonne, which is the special name for a megagram, is used with the
prefixes "kilo" and "mega" only.
Pronunciation of the prefix and the unit is not altered by their
combination. Kilogram, for example, is pronounced as if it were two
words with approximately equal emphasis on each. The prefix "kilo" is
pronounced as "killo" regardless of the unit to which it is attached.
But thenm, you could always pronounce them the way the inventors, the
French do. For a decent argument on KILLO-meters versus kilOMetres,
please contact Gough Whitlam
For scientific and technical calculations all measurements should be
expressed in terms of the SI unit. Non-SI units should not be used in
such calculations.
See
http://www.newcastle.edu.au/department/bi/birjt/techinfo/units_si.html
For an Australian view.
Geoff Lambert