You forgot about
AREA
Under a strict "powers of 1000" system, the only acceptable and practical
units for area are mm�, m�, and km�. These differ by a factor of 1 000 000,
so many measurements would have to be expressed with very large numbers.
The area of a sheet of A4 paper, for example, has to be described as "62 500
mm�." A farm could be "800 000 m�."
Now, could someone please explain why that's more suitable than "625 cm�" or
"80 ha"?
----- Original Message -----
From: "Hooper, Bill and or Barbara" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[EMAIL PROTECTED]>
Sent: Wednesday, November 1, 2000 10:04
Subject: [USMA:8920] Re: Preferred/non-preferred prefixes
> Many of you have countered my argument in favor of voluntarily phasing out
> the use of the special prefixes centi, deci, hecto and deka. The arguments
> always seem to center on the centimetre.
>
> But let me draw a comparison between length and mass:
>
> LENGTH
> If we wish to express the length of 152 cm without using the centi (or
deci)
> prefixes, we could use either 1.52 m or 1520 mm. Several of you have
argued
> that 1520 mm is too long and furthermore implies a precision of 1 mm which
> may not be warranted.
>
> But you miss the point when you assume I am arguing in favor of using 1520
> mm. I am not. I am arguing that one may use either metres OR millimetres,
> WHICHEVER IS MORE SUITABLE. If 1520 mm is not suitable (as noted above),
> then use 1.52 m. Where's the problem?
>
> MASS
> Now please compare this with a similar situation involving mass. Suppose
> something has a mass of 1.52 kg which is also 1520 g. Does anyone
seriously
> think it would be a good idea to express this in centigrams: 152 cg? That
> would be perfectly valid SI usage but I think it would be highly
> inappropriate. No one uses centigrams for measuring anything. Let's not
> start using centi there, where it is not already in common use.
>
> If we don't need centi for centigrams, then I fail to see why we really
need
> centi for centimetres. The situations are the same. (Notice I wrote
"NEED",
> not "WANT".)
>
> We are unfortunately stuck with the historical fact that centi is in VERY
> common use for lengths in centimetres. Fine! So we can accept the
continuing
> use of it there. But let's not start measuring masses in centigrams (and
> time in hectoseconds or voltage in dekavolts or power in deciwatts, etc).
>
> The base unit plus the prefixes kilo and milli will suffice for virtually
> ALL common measurements (and the other powers-of-1000 prefixes will
suffice
> in any case where killo and milli are not large or small enough).
>
> Centi (and deci and deka and hecto) may be WANTED by some peole, but they
> are not NEEDED.
>
> Regards,
> Bill Hooper
>
> PS I appreciate this vigorous exchange of ideas. I hope no one interprets
> this discussion of our varying views to indicate that we are not all
united
> in promoting the general adoption of SI.
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