25 Jan
1999
25 Jan
'99
3:15 a.m.
It was thus said that the Great Hans Franke once
stated:
> > Philip.Belben(a)pgen.com wrote:
> > > Metre, Kilogram, Second, Ampere, Kelvin, Mole and Candela (normally
> > Kilogram? Why not gram?
> Since the base unit is the Kilogram. As Philip said,
> the Mass is still defined by the artefact kilogram
> in Paris - there is no other definition until now.
Uh, I thought a gram was defined as 1 cc of water at
4C. A kilogram is
1,000 cc of water at 4C, which is one litre of water (a litre being 1,000 cc
volume).
Basicly there should have been a unit called grave, that equals
the weight of 1 dm water - but after the french revolution, the
new politicians (the original metric system idea was _not_ an
invention of the revolution - most work, including the definiton
had already been done by a kings commision, ordered by Louis XVI -
the revolutionaries just took the fruit)decided that it would be
better to have a gramme as basic unit - since most (fine/exact)
measurements would be based on smaler units than a (what now is
know as) kg. They just had a technical problem - a prototype of
a g unit would be very small, and to get the same acuracy the
methods of production had to be 1000 times more exact than for
a kilogramme (for example if there is a complete layer of atomes
'to much' around the prototype, it inflicts a 1g prototype 1000
times as much as a 1 kg prototype). So the definition of the kg
as the base unit is a mixed up of usability and technical
possibilities.
In fact, the logical base unit would have been a ton:
one m^3 of water.
Gruss
H.
--
Ich denke, also bin ich, also gut
HRK