Tom Wade, Group:
To get people to "think metric...".....
I see the NEED to 'think metric' and relate measurements to definition of
the METRE.
While, it is NOT my intention to revoke a discussion of TIME at this list,
there is a need to see things beyond. Long ago, I sent some documentation to
United Nations through UN Iformation Office in New Delhi; and later followed
up thro Indian Mission, New York in 2002 May:
http://www.brijvij.com/Ind-Mission20020521.doc
Several upgrades have been made during my discussions with
<[email protected]> and <[EMAIL PROTECTED]>. A brief, however can
be seen at:
http://www.the-light.com/cal/bbv_IndiaContributes.doc
Regards,
Brij Bhushan Vij
(Monday, Kali 5106-W49-01)/D-081(Tuesday, 2006 March 21H16:97(decimal) ET
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From: Tom Wade <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
To: "U.S. Metric Association" <[email protected]>
Subject: [USMA:36337] RE: Prefix choices
Date: Tue, 21 Mar 2006 14:31:24 +0000
Greetings,
But if we are going to get people to use the SI in their personal lives we
will have to 'allow' the centimeter for use. One of the frequent grips
against the SI is that (to some people) it does not feel "natural" because
(they say) it does not related to a 'body measurement'. To get people to
"think metric..." we have to come up with something they can readily see
for a comparison.
I am in complete agreement with Linda. The cm is every bit as SI as the
mm, and which you use depends on which is more appropriate to the
particular
application. Where you need the precision, then mm is the one to us, which
would cover engineering and scientific applications. Where you don't need
more precision, then cm are just fine (the whole number argument only
applies
if you have to use something like 4.5 cm, but then you need greater
precision
than 1 cm, so mm would be better).
Ultimately, it is to be hoped that people will be using metric units for
their
height, and that is a very good example of cm precision. I doubt if even
in
Australia people measure their heights in mm. It is more likely to be done
in
cm (note that a height of 1.74 m will probably be spoken as "one seventy
four"
which although in meters is really a cm measure). Getting someone to
remember
their height as 1741 mm rather than 174 cm is simply not going to happen.
Other examples of quantities that people might want to measure in which cm
are the more appropriate are:
How far from the kerb have I parked ?
What size monitor is this ?
How high should I hang this mirror ?
There are quite a lot of things you will come into contact with in everyday
life, whose size you want to estimate, but not to more than a 1 cm
precision.
I have never bought into the argument that using cm slows down a metric
transition. It is just that the areas that used the mm (because they
needed
the precision) went better because the benefits from whole-number usage
were
a significant advantage over fractions of an inch. The clothing industry
adopted cm because they don't need the level of precision of mm, and thus
the
benefit of metrication wasn't a huge advantage over inches. I doubt if
metrication would be any faster if they chose to label clothes in mm sizes
(in fact, it would have made metric quantities far more unwieldy, and thus
slowed down metrication "damn, there are only 846 mm waist sizes - where
are
the 849 mm ?").
People's perception of numbers is not linear. For example, 10 000 km and
100 000 km are an order of magnitude apart. So are 10 cm and 10 mm, but
people are more sensitive to changes with small numbers, so the same prefix
is fine for the first two, but it's handy to have a choice for the latter.
This is why there is greater granularity (every ten) in prefixes around the
base unit than further away (every thousand).
There is a danger of overenthusiastic simplification here. Remember this
is
a system to be used by ordinary people. Pick the prefix that you are most
comfortable with, but when educating, you must include everything between
mega and micro at the very least.
The centimeter and the liter are your friends.
---------------------------------------------------------
Tom Wade | EMail: tee dot wade at eurokom dot ie
EuroKom | Tel: +353 (1) 296-9696
A2, Nutgrove Office Park | Fax: +353 (1) 296-9697
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