Re: can someone explain the candela a little?
- From: Oz <Oz@xxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 7 Apr 2005 14:30:09 +0000 (UTC)
Ralph Hartley <hartley@xxxxxxxxxxxxxxxx> writes
>
>The concept of force existed for thousands of years independent of time,
>length, and mass. (I don't know what you mean by a *concept* existing
>"in nature")
>
>The relationship is a rather recent discovery.
Indeed, Mr Newton.
Personally I would suggest this is not 'recent'.
>Archimedes knew quite a bit about force, but I doubt he used units of
>mass*length/time^2 (not "solely" nor "naturally" nor at all). Naturally
>he used the same units as mass, a practice that survives to this day.
And which causes endless problems with starting mechanics students and
probably engineering students to this day. Force is NOT mass.
>The natural relationship between force and mass in normal life is that
>determined by gravity (on earth).
Yes.
>Produce (in the US) is *still* sold by the pound.
Considering how smug americans were during the war because they had a
strightforward decimal currency whilst we brits used the archaic LSD, I
find their attachment to archaic units hilarious.
>The pound originated
>as a unit of mass. It was later converted into a unit of force.
Its never been a unit of force (since newton).
The unit of force is (dregs memory) the poundal and IIRC one pound mass
weighs 32 poundals.
>At least
>that's what the textbooks say. It is used far more as a unit of mass. No
>one *ever* uses the "slug".
Its unfortunate to find a physicist using mass as a unit of force.
I have been skinned alive here for less....
>The Newton is better known, but it's use requires knowing a (non power
>of ten) constant in a system that otherwise lacks them. That's is one of
>the (few) advantages of the "English" system: a pound of something
>weighs one pound. A Kilo weighs 9.?? Newtons, I'd have to look it up.
Its 10 as far as engineers need (9.81)....
In english g=32 fpss isn't it?
Ye gods its amazing how stuff learned in youth persists...
>Force measuring devices are *still* the dominant means of measuring mass.
So what?
Resistance is the dominant means of measuring light...
>Of course we are now so aware of the relationship between force, mass,
>length, and time, that it is hard to imagine anyone *not* knowing.
Oh yes it is.
>But we now also know the relationship between length and time as well.
>If you follow your argument to its logical conclusion, you *must*
>advocate the elimination of the meter as well. It is, after all,
>proportional to the second, not a "different kind of stuff" at all.
I'd be very happy to loose the meter and measure in nanoseconds.
Of course this works out at about a foot .....
--
Oz
This post is worth absolutely nothing and is probably fallacious.
Use oz@xxxxxxxxxxxxxxxxxxxx [ozacoohdb@xxxxxxxxxxxxx functions].
BTOPENWORLD address has ceased. DEMON address has ceased.
.
- References:
- can someone explain the candela a little?
- From: robert bristow-johnson
- Re: can someone explain the candela a little?
- From: J. J. Lodder
- Re: can someone explain the candela a little?
- From: robert bristow-johnson
- Re: can someone explain the candela a little?
- From: Ralph Hartley
- can someone explain the candela a little?
- Prev by Date: Re: can someone explain the candela a little?
- Next by Date: General Relativity Question: Wald...Derivative Operators.
- Previous by thread: Re: can someone explain the candela a little?
- Next by thread: Re: can someone explain the candela a little?
- Index(es):
Relevant Pages
|
