On 04/06/12 15:07, James Knott wrote:
Mike Scott wrote:
No way!!! Remind us what the original intent of the metre was - and
how wrong (and pointless). And the current definition is, well,
arbitrary, is it not?
And how do entities like the litres and are fit into a "rational"
system that already has cubic this and square that?
The original "metre" was 1/10,000,000 the distance between the equator
and pole. It was later refined to the distance light travels in 1 ⁄
As I said, arbitrary, and pointless.
299,792,458 second. The second is defined by the oscillations of the
cesium atom. Now consider water. One millilitre (1 cm³ or cc) has a mass
of 1 gram.
Approximately. But so what?
> .... A litre = 1000 cc and 1 Kg. Nice and convenient that. Now
what about the weight and dimensions of an ounce of water? U.S. vs
A pint of water weighs a pound and a quarter. At least, on my side of
the Atlantic. It even rhymes. A fluid ounce of water is just that - an
ounce.
(Although you then land with asking about at what temperature and
pressure - just as with mg and ml (or is that cc? See? :-) )
But a litre = 1000cc - so what? It's an introduction of another
pseudo-fundamental unit, because it's "about the right size" for real
use (a cubic metre is rather a lot :-) ). Rather like the imperial
system, I find. Similarly with the are (which I had to look up - a
square decametre)
imperial ounce? U.S. or imperial quart? Gallon? When you work in science
or engineering the metric system works out extremely well due to the
easy scaling. You certainly can't say the same for the various
traditional units.
I wouldn't try to. My point is that the metric system is fundamentally
just as irrational, and twice as pointless :-)
For my own part, I do as I'd advice others: use whichever is convenient
for the job in hand. And don't mix 'em. You make expensive craters on
Mars like that :-}
--
Mike Scott
Harlow, Essex, England
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