SI units, anyone ever use "megagram?"
John Wesley Powell
I've seen the term "megagram" used in some recent USGS reports in place
of the more common "metric ton." It seemd wierd, but someone I know in
the USGS showed me chapter and verse from Suggestions to Authors of the
Reports of the USGS:
"Metric Ton (t) as a name for megagram (Mg) should be restricted to
commercial usage, and no prefixes should be used with it." (p. 122)
This is apparently the way things go by the rules of the SI measurement
system. Also note that liters, hectares, and centimeters, some of the
more useful units in the metric system are not really legitimate SI
units. But I'll refrain from flaming the SI system in this forum...(and,
to be fair to USGS, they allow the use of "liter" and "hectare.")
Before I started reading USGS reports I'd never heard anyone use the term
"megagram," though I was was familiar with 100 "megaton" nuclear bombs from
my Cold War childhood. ("Duck and cover!") But before I shoot off my
flame thrower at our scientific public servants, perhaps I shoulds check
to see if anyone outside the USGS uses the term "megagram."
This sort of thing is pretty anal-retentive, IMO. No wonder USGS has such
a reputation for late reports if they obsess about stuff like this!
[And, of course, any flames I get about _me_ obsessing about this will be
sent immediately to /dev/null :)]
And, finally, I would hate to see the use of a good term like "Megaton"
get trashed. After all, what would we do if the USGS produced Cold-War
thriller movies? "Mr. President, if we don't stop those renagade Green
Berets, they'll drop a 100 teragram nuclear warhead on Moscow and start
World War II!!" "Teragram" just doesn't have the same flavor as "megaton."
John Wesley Powell
Colorado River Boat Tours, Inc.
"We comply with the provisions
of the Americans with
Disabilities Act."
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Byron Bodo
>
>
> I've seen the term "megagram" used in some recent USGS reports in place
> of the more common "metric ton." It seemd wierd, but someone I know in
> the USGS showed me chapter and verse from Suggestions to Authors of the
> Reports of the USGS:
>
> "Metric Ton (t) as a name for megagram (Mg) should be restricted to
> commercial usage, and no prefixes should be used with it." (p. 122)
>
Having lived with SI for 20+ years, I've yet to see any usage
of Mg in Canada or Europe. The tonne or metric ton has been
widely used in bilateral Canada-US Great Lakes work to describe
mass where appropriate (e.g., sediment flows) since the mid 1970s
& also for quantifying SO2 emissions of acid rain import.
I can't recall any problems or protests.
Generally, common sense and convenience have been the prevailing
factors, e.g. mass is given in pg, mg, g, kg, t, or whatever to
avoid using exponential notation or excessive decimal digits.
The restriction of tonnes to commercial usage seems rather
arbitrary & a tad silly.
-bb
Dimitri Shcherban
>an17...@anon.penet.fi (John Wesley Powell) wrote:
>>
>>
>> I've seen the term "megagram" used in some recent USGS reports in place
>> of the more common "metric ton." It seemd wierd, but someone I know in
>> the USGS showed me chapter and verse from Suggestions to Authors of the
>> Reports of the USGS:
>>
>> "Metric Ton (t) as a name for megagram (Mg) should be restricted to
>> commercial usage, and no prefixes should be used with it." (p. 122)
>>
>factors, e.g. mass is given in pg, mg, g, kg, t, or whatever to
>avoid using exponential notation or excessive decimal digits.
Well, in my country SI is translated as meter-kilogram-second system of units.
Which is quite different from older SGS (or CGC - I don't really know English
notation for this) which was based on cantimeter-gram-second principle, so to
say.
As a matter of fact the last one was abandoned mostly because all of common
numbers
came out toobig to handle.
IMHO, megagram sounds simply stupid! SI official description sais that basic
unit for mass is kilogram, so we can speak only about kilokilogram %-( But it
will be at least comletely correct and legal.
just to add some fun:
- The atmospheric pressure today will be about 0.11 gectapascals (sp?)
- salt concentartion in this solution is 0.1 once per gallon
Both phrases are from real life! Enjoy, Dima.
Wolfgang Pomrehn
> - The atmospheric pressure today will be about 0.11 gectapascals (sp?)
What to hell is gecta? Do you mean hecto? But air pressure of 0.11 hPa
would us realy cause trouble! ( 1 hPa = 1 mbar )
Actually in Germany hPa is used because, according to the SI rules
pressure should be measured in pascal not in bar.
But since hPa and mbar are equivalent that makes no big difference. It
just may sound strange to somebody not used to it. More problems are
caused by measures like Fahrenheit.
Wolfgang Pomrehn
--------
Wolfgang Pomrehn
kle...@mixer.toppoint.de
## CrossPoint v3.02 R ##
Michael Olea
>In article <5pD09...@mixer.toppoint.de>, kle...@mixer.toppoint.de
>says...
>>
>>di...@essc.psu.edu wrote on 04.07.95:
>>> - The atmospheric pressure today will be about 0.11 gectapascals (sp?)
>>
>>What to hell is gecta? Do you mean hecto?
>In the movie "Back to the future", in the french version,the Doc said
>(several times) that his time vehicle possess "a power of xxx Gigowatts"
>(gigot in french means the leg of the mutton).
>Is it the same in the original american version?
>Jean-Michel Le Cleac'h, Paris, France
Nope. In the American original the Dr. refers to "jiggerwatts",
which refers to the power of one dram (proof enough).
Le Cleac'h Jean-Michel
DaveHatunen
Le Cleac'h Jean-Michel <lecl...@cgi.ensmp.fr> wrote:
>In the movie "Back to the future", in the french version,the Doc said
>(several times) that his time vehicle possess "a power of xxx Gigowatts"
>(gigot in french means the leg of the mutton).
>Is it the same in the original american version?
Interesting. In the English version Doc says "gigawatts" with both of
the g's hard (as "guigawatts"). Since "giga-" is the prefix for 10^9,
it makes me now wonder: How is "giga-" pronounced in French? Is the
first "g" soft?
--
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* As one IS manager put it, "If you make an interface so easy *
* that any Bozo can use it, every Bozo will, and they'll all *
* want IS support, and they'll all be in my office asking how *
* to make their own Home pages the way horny undergraduates go *
* around asking each other's majors and astrological signs." *
* *
* --InfoWorld, Vol 17, Issue 5, June 19, 1995 *
****************************************************************
Gerard Middleton
Up here in chilly Canada we are quite used to using SI units -- in fact
my students learn nothing else in school. So it does not bother me
(much) that the temperature today is a muggy 27 degrees (Celcius) and the
atmospheric pressure is somewhat over 100 kilopascals, or that I have to
take the bus some 8 km to get home.
Funny how soon you get used to these things -- after all there was a time
I had to worry about poundals and British thermal units, not to mention
the confusion caused by differences between the US and Imperial gallon.
--
Gerry Middleton
Department of Geology, McMaster University
Tel: (905) 525-9140 ext 24187 FAX 522-3141
Le Cleac'h Jean-Michel
>How is "giga-" pronounced in French?
>Is the first "g" soft?
Yes we don't use the original greek prononciation with the hard G before the I and the
A.
The french language possess stranges rules:
"garcon, guttural, gorille" are pronounced with a hard G
"girafe, gypse, geler..." are pronounced with a soft G.
If we need to have a hard G to be pronounced we add a U after the G:
"guitare, guerre..."
So in the "giga" french pronounciation the first g is soft and the second is hard, it
gives something like "jeega"
Best regards
DaveHatunen
Gerard Middleton <midd...@mcmail.cis.McMaster.CA> wrote:
>
>Up here in chilly Canada we are quite used to using SI units -- in fact
>my students learn nothing else in school. So it does not bother me
>(much) that the temperature today is a muggy 27 degrees (Celcius) and the
>atmospheric pressure is somewhat over 100 kilopascals, or that I have to
>take the bus some 8 km to get home.
>
>Funny how soon you get used to these things -- after all there was a time
>I had to worry about poundals and British thermal units, not to mention
>the confusion caused by differences between the US and Imperial gallon.
It's interesting that some of the things you mention are just as
arbitrary as the English system.
Temperature is arbitrary. There is no rational way, connected to the rest
of the units, to define the degree. Of course, if you change the size
of the degree of temp you change the size of the calorie, but that
doesn't matter either: it would still fit into an SI just as well.
And the confusion of poundals and slugs and pounds isn't much different
than the confusion of kilograms and Newtons. You still have a factor of
"g" to consider and use properly. Ask your average European how much a
loaf of bread weighs, and I doubt very much the answer will be in
Newtons.
Aside from the fact that most of the world has agreed to use it, the
SI's only true advantage is the inventing of decimally consistent
units. And the English system was/is pretty much headed that way, too.
Very few automobile pistons are specified in inches and binary
fractions thereof; thousandths are used, or even the mildly misleading
"tenth" (ten-thousandth). And except for architects, the feet-inches
system is not used much; most major projects are done in feet and
hundredths of a foot.
Dave Halliwell
>Funny how soon you get used to these things -- after all there was a time
>I had to worry about poundals and British thermal units, not to mention
>the confusion caused by differences between the US and Imperial gallon.
...especially when you have to take into account the difference in size
between US and Imperial fluid ounces....
--
Dave Halliwell I don't speak for my employers, and you
Edmonton, Alberta shouldn't expect them to speak for me.
Stephan Logan
>pressure should be measured in pascal not in bar.
>But since hPa and mbar are equivalent that makes no big difference. It
>just may sound strange to somebody not used to it. More problems are
>caused by measures like Fahrenheit.
Actually I think the correct unit is the kiloPascal. Standard pressure
is 101.1 kPa.
Thorsten Kallnischkies
>>What to hell is gecta? Do you mean hecto?
>In the movie "Back to the future", in the french version,the Doc said
>(several times) that his time vehicle possess "a power of xxx Gigowatts"
>(gigot in french means the leg of the mutton).
Whereas the Hitchhiker's Guide to the Galaxy (D. Adams) claims that a
certain and widely used gun does hundreds of Mega-Hurts.
As a contanental eurapean I can cope with that, but *not* with Glbs/psqin.
Thorsten Kallnischkies
"see if I don't"
Prostnetic Vogon Jeltz
Marc de Jonge
: >Actually in Germany hPa is used because, according to the SI rules
The 'correct' unit is to a large degree up to the user, I'd prefer 1011 hPa
for SP as it is one key less to type and is equivalent with the unit for
atmospheric pressure people were used to in the CGS system (mbar).
-------------
Marc de Jonge (dej...@geof.ruu.nl)
Wolfgang Pomrehn
>
> Up here in chilly Canada we are quite used to using SI units -- in fact
> my students learn nothing else in school. So it does not bother me
> (much) that the temperature today is a muggy 27 degrees (Celcius) and
> the atmospheric pressure is somewhat over 100 kilopascals, or that I
> have to take the bus some 8 km to get home.
Do you realy use kilopascals? That's funny, indeed. Why not hectopascal?
That would be easier because you wouldn't have to change the figures? Btw,
I am wondering what units are used in other countries. Is there any other
countrie than Germany using hPa? Or is it just a stupid speciality?
Gerard Middleton
Yes, Canada really does use kilopascals. A couple of small points about
SI units: unit names are not capitalized, even when named after people,
e.g. the person is Pascal, the unit is pascal. The prefered compound is
a multiple or divisor of 1000, so for metres (yes, in Canada we spell it
that way) prefered units are km and mm, not cm, dm, hm etc. So I believe
that kilopascals should be the prefered unit for meteorology.
Joseph Hearst
Powell) writes:
>
>
>I've seen the term "megagram" used in some recent USGS reports in
place
>of the more common "metric ton." It seemd wierd, but someone I know
in
>the USGS showed me chapter and verse from Suggestions to Authors of
the
>Reports of the USGS:
>
>"Metric Ton (t) as a name for megagram (Mg) should be restricted to
>commercial usage, and no prefixes should be used with it." (p. 122)
>
of grams per cubic centimeter when we are required to use SI in a
report. It is a convenient locution since the values are the same.
>----------------------------------------------------------------------
Dave Halliwell
>And the confusion of poundals and slugs and pounds isn't much different
>than the confusion of kilograms and Newtons. You still have a factor of
>"g" to consider and use properly. Ask your average European how much a
>loaf of bread weighs, and I doubt very much the answer will be in
>Newtons.
I don't know about that: when a value in pounds is given, is that a
pound in the pound/poundal pair, or a pound in the slug/pound pair?
At least in SI, when a person says "I weigh 80 kg", you know they
really mean mass. What do you do if a person says "the weight of the
object is 12 pounds"? Take them at face value, or decide that the mass
was really 12 pounds?
>Aside from the fact that most of the world has agreed to use it, the
>SI's only true advantage is the inventing of decimally consistent
>units. And the English system was/is pretty much headed that way, too.
>Very few automobile pistons are specified in inches and binary
>fractions thereof; thousandths are used, or even the mildly misleading
>"tenth" (ten-thousandth). And except for architects, the feet-inches
>system is not used much; most major projects are done in feet and
>hundredths of a foot.
To bring back a bit of geology, I've had arguments from a couple of
old fossils that feet and inches are much better than metric, because it
is much easier to divide them appropriately. The exact quote was, if I
remember correctly, that "you can divide 12 by anything". Further
discussion clarified that to mean "it's easier to divide a foot by
three".
I hadn't realized how difficult it was to divide 30cm by three. :-)
Byron Bodo
>
> midd...@mcmail.cis.McMaster.CA (Gerard Middleton) writes:
>
> >Funny how soon you get used to these things -- after all there was a time
> >I had to worry about poundals and British thermal units, not to mention
> >the confusion caused by differences between the US and Imperial gallon.
>
> ...especially when you have to take into account the difference in size
> between US and Imperial fluid ounces....
>
Quick. How many of those in an acre-foot ?
-bb
John Tauxe
+---------------------------------------------------------------------------+
| |
| John Tauxe ### |
| Oak Ridge National Laboratory ##### #### ###### ## |
| tau...@ornl.gov ## ## ### ## ## ## ## |
| ## ## ## ## ## ## |
| "It's my job to be cleaning up this ##### #### #### ###### |
| mess and that's all right with me."-JB http://www.ornl.gov/home.html |
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+---------------------------------------------------------------------------+
John Tauxe
>
>Yes, Canada really does use kilopascals. A couple of small points about
>SI units: unit names are not capitalized, even when named after people,
>e.g. the person is Pascal, the unit is pascal. The prefered compound is
>a multiple or divisor of 1000, so for metres (yes, in Canada we spell it
>that way) prefered units are km and mm, not cm, dm, hm etc. So I believe
>that kilopascals should be the prefered unit for meteorology.
However, the _abbreviation_ is capitalized when named after a person,
in this case to Pa, or kPa.
I am a promoter of SI units, and it is not an easy role in the US,
especially in engineering. The toughest ones to get through around here
(we're up to our eyeballs in radioactivity) are the radiological units:
Bq instead of Ci, Sv instead of rem, and Gy instead of rads.
These are SI, but damned if I can get poeple to use 'em.
John Tauxe
In the USCS (US Customary System) we refer to large volumes of water in
acre-feet (AF), or thousand acre-feet (TAF). Here ar ORNL we are soing SI,
and I recently wrote some documents requiring these volumes. I chose the
cubic hectometer hm^3, which at forst sounds wacky, but is sort of like
a cubic hectare -- 100 m on a side. It is also a close conversion, since
1 AF = 1.23 hm^3.
What is the SI standard for this sort of thing?
And flow: 1.0 MGD -> 1.12 TAF/y -> 1.38 hm^3/y
What would you do?
Byron Bodo
>
> I don't get it -- what's wrong with Mg? It's a perfectly good unit!
>
So's the tonne , kilotonne, etc. Just saw another emission inventory
done in t, kt, etc. The move to kill the tonne seems to be
a U.S. bureaucratic initiative. Anyone smell a conspiracy ?
-bb
DaveHatunen
Dave Halliwell <dhal...@nofc.forestry.ca> wrote:
>hat...@netcom.com (DaveHatunen) writes:
>
>>And the confusion of poundals and slugs and pounds isn't much different
>>than the confusion of kilograms and Newtons. You still have a factor of
>>"g" to consider and use properly. Ask your average European how much a
>>loaf of bread weighs, and I doubt very much the answer will be in
>>Newtons.
>
> I don't know about that: when a value in pounds is given, is that a
>pound in the pound/poundal pair, or a pound in the slug/pound pair?
A pound is a unit of force, not mass. Of course it's confusing. That
was my point.
> At least in SI, when a person says "I weigh 80 kg", you know they
>really mean mass. What do you do if a person says "the weight of the
>object is 12 pounds"? Take them at face value, or decide that the mass
>was really 12 pounds?
When a person says "I weigh 200 lb", I think we all know what he means,
too, so I don't get your point.
A kilogram is a unit of mass, not force. Since weight is a force
concept, it is incorrect, although common, to say "I weigh 80 kg".
Scientifically speaking (we were speaking scientifically, weren't we?)
SI weight should be expressed in newtons. This is also confusing.
>>Aside from the fact that most of the world has agreed to use it, the
>>SI's only true advantage is the inventing of decimally consistent
>>units. And the English system was/is pretty much headed that way, too.
>>Very few automobile pistons are specified in inches and binary
>>fractions thereof; thousandths are used, or even the mildly misleading
>>"tenth" (ten-thousandth). And except for architects, the feet-inches
>>system is not used much; most major projects are done in feet and
>>hundredths of a foot.
>
> To bring back a bit of geology, I've had arguments from a couple of
>old fossils that feet and inches are much better than metric, because it
>is much easier to divide them appropriately. The exact quote was, if I
>remember correctly, that "you can divide 12 by anything". Further
>discussion clarified that to mean "it's easier to divide a foot by
>three".
What if we just dropped inches and miles and used feet for everything?
--
********** DAVE HATUNEN (hat...@netcom.com) **********
* Daly City California: almost San Francisco *
* but with parking and lower car insurance rates *
*******************************************************
Dave Halliwell
>In article <3tsbr4$l...@minotaur.nofc.forestry.ca>,
>Dave Halliwell <dhal...@nofc.forestry.ca> wrote:
>>hat...@netcom.com (DaveHatunen) writes:
>>>And the confusion of poundals and slugs and pounds isn't much different
>>>than the confusion of kilograms and Newtons. You still have a factor of
>>>"g" to consider and use properly. Ask your average European how much a
>>>loaf of bread weighs, and I doubt very much the answer will be in
>>>Newtons.
>> I don't know about that: when a value in pounds is given, is that a
>>pound in the pound/poundal pair, or a pound in the slug/pound pair?
>A pound is a unit of force, not mass. Of course it's confusing. That
>was my point.
More confusing than you might suspect, because clearly one of the two
of us is confused about pounds and poundals.
In the slugs/pounds system of units, slugs are mass and pounds are
force. However, in the pounds/poundals system, my impression was that
pounds are mass and poundals are force. An object with a mass of one
pound in the pound/poundal system has a weight of one pound in the
slugs/pounds system.
Unfortunately, none of the physics texts that I have on hand discuss
the pounds/poundals system, so I can't confirm that I am correct
regarding its use of pounds as units of mass. Should I interpret your
paragraph above as an indication that you think that pounds are force and
poundals are mass, or that you are not familiar with that set of units?
>> At least in SI, when a person says "I weigh 80 kg", you know they
>>really mean mass. What do you do if a person says "the weight of the
>>object is 12 pounds"? Take them at face value, or decide that the mass
>>was really 12 pounds?
>When a person says "I weigh 200 lb", I think we all know what he means,
>too, so I don't get your point.
...prehaps because of a disagreement on what constitutes the
pound/poundal system?
>> To bring back a bit of geology, I've had arguments from a couple of
>>old fossils that feet and inches are much better than metric, because it
>>is much easier to divide them appropriately. The exact quote was, if I
>>remember correctly, that "you can divide 12 by anything". Further
>>discussion clarified that to mean "it's easier to divide a foot by
>>three".
>What if we just dropped inches and miles and used feet for everything?
What if we just decide to use furlongs per fortnight for speed?
John Tauxe
>What if we just dropped inches and miles and used feet for everything?
If we all used our feet for a few miles, we could probably drop a
couple of inches, eh? ;*)
John Tauxe
tau...@ornl.gov
DaveHatunen
Dave Halliwell <dhal...@nofc.forestry.ca> wrote:
>hat...@netcom.com (DaveHatunen) writes:
>
>>In article <3tsbr4$l...@minotaur.nofc.forestry.ca>,
>>Dave Halliwell <dhal...@nofc.forestry.ca> wrote:
>>>hat...@netcom.com (DaveHatunen) writes:
>
>>>>And the confusion of poundals and slugs and pounds isn't much different
>>>>than the confusion of kilograms and Newtons. You still have a factor of
>>>>"g" to consider and use properly. Ask your average European how much a
>>>>loaf of bread weighs, and I doubt very much the answer will be in
>>>>Newtons.
>
>>> I don't know about that: when a value in pounds is given, is that a
>>>pound in the pound/poundal pair, or a pound in the slug/pound pair?
>
>>A pound is a unit of force, not mass. Of course it's confusing. That
>>was my point.
>
> More confusing than you might suspect, because clearly one of the two
>of us is confused about pounds and poundals.
I'm not sure how I can be conffused about it when I've never used
thewword up to this point.
> In the slugs/pounds system of units, slugs are mass and pounds are
>force. However, in the pounds/poundals system, my impression was that
>pounds are mass and poundals are force. An object with a mass of one
>pound in the pound/poundal system has a weight of one pound in the
>slugs/pounds system.
F = mg. 1 lb = 1 slug x 32.2 ft/s^2
A poundal is the force required to acellerate a 1 lbm 1 ft/s^2.
This gets tricky, and was always hard to explain to my students. It was
even harder since back when I taught Physics we taught in both the
English and MKS systems, so we had to teach it twice.
The pound, bare-naked as it were, is a unit of force. But the mass that
results in a downward force (weight) of one pound under standard earth
gravity is sometimes referred to as the pound-mass (lbm).
> Unfortunately, none of the physics texts that I have on hand discuss
>the pounds/poundals system, so I can't confirm that I am correct
>regarding its use of pounds as units of mass.
Yeah. it makes it a bit easier for today's high school physics
teachers. AS I say, teh lbm is sometimes used as a unit of mass.
Especailly by enginers stuck with English units.
>Should I interpret your
>paragraph above as an indication that you think that pounds are force and
>poundals are mass, or that you are not familiar with that set of units?
Pounds are force.
Poundals are force.
Slugs are mass.
Pound-masses are mass.
That's what I meant by confusing.
>>> At least in SI, when a person says "I weigh 80 kg", you know they
>>>really mean mass. What do you do if a person says "the weight of the
>>>object is 12 pounds"? Take them at face value, or decide that the mass
>>>was really 12 pounds?
>
>>When a person says "I weigh 200 lb", I think we all know what he means,
>>too, so I don't get your point.
>
> ...prehaps because of a disagreement on what constitutes the
>pound/poundal system?
No, not really. Waht cosntitutes the system is easy to look up if you
have the right references. Being an old fart, my old copy of the CRC
Handbook fo Chemistry and Physics has defintions for them all.
The Kilogram is a unit of mass. But to keep the non-scientific folk
comfortable, tehre is also the kilgram-force (kgf), which is the
downward force exerted by a kilogram in normal earth gravity, and
which is therefore equal to 9.8 newtons.
>>> To bring back a bit of geology, I've had arguments from a couple of
>>>old fossils that feet and inches are much better than metric, because it
>>>is much easier to divide them appropriately. The exact quote was, if I
>>>remember correctly, that "you can divide 12 by anything". Further
>>>discussion clarified that to mean "it's easier to divide a foot by
>>>three".
>
>>What if we just dropped inches and miles and used feet for everything?
>
> What if we just decide to use furlongs per fortnight for speed?
AS long as everybody does it...
Actually, civil engineers msotly use feet for everything.
Kjell T. Svindland
> I don't get it -- what's wrong with Mg? It's a perfectly good unit!
No, it is not. Consider the consequences if someone confuses 1 Mg and 1 mg!
--
Kjell T Svindland
kje...@ibg.uit.no
L. Joeseph Bachman
> I don't get it -- what's wrong with Mg? It's a perfectly good unit!
>
Well, for that matter, what's wrong with centimeter (cm), which is
apparently not an offcial SI unit, but IMO, it has a lot more utility
than Mg.
Folks in the metric world have been using "ton" or "tonne" or "metric ton" for
years without any problems before the SI. So why replace a well-known and
well used term for something new just because it fits into some sort of
rationalistic naming system?
Just my personal opinion, of course. I do my best to use SI units when
writing my official stuff.
Joe Bachman
jbac...@usgs.gov
L. Joseph Bachman
>In article <3u3sp2$9...@stc06.ctd.ornl.gov>, John Tauxe <tau...@ornl.gov> wrote:
>> I don't get it -- what's wrong with Mg? It's a perfectly good unit!
>No, it is not. Consider the consequences if someone confuses 1 Mg and 1 mg!
>--
That's right. For example, I am getting over a mild bout of the flu:
"Doc, I feel lousy."
"Take 500 Mg of Tylenol and call me in the morning."
Well, my doc meant for me to take 2 tablets of Extra-Strength Tylenol.
But if he meant megagrams... Hmm.. 1 Mg is 10^12 mg... So I need to take
_2 TRILLION_ Tylenol Tablets... I don't even know if they make that much
Tylenol in a year. If I swallow one every 10 seconds, it will take me
about 230 million days or about 630 thousand years to finish the first
dose of the prescription. Heck, I'll probably forget to call the doctor
in the morning!
And what's more, I've _seen_ medicines with the term "Mg" printed right
on the label, yet I've been able to pick up the box, pay for it and carry
it home. Maybe they have some sort of anti-gravity device hidden in the
packaging. :-)
Speaking for no one except myself,
Joe Bachman
jbac...@access.digex.net
John Tauxe
>kje...@ibg.uit.no (Kjell T. Svindland) writes:
>
>>In article <3u3sp2$9...@stc06.ctd.ornl.gov>, John Tauxe <tau...@ornl.gov> wrote:
>
>>> I don't get it -- what's wrong with Mg? It's a perfectly good unit!
>
>>No, it is not. Consider the consequences if someone confuses 1 Mg and 1 mg!
>
>
>"Doc, I feel lousy."
>
>"Take 500 Mg of Tylenol and call me in the morning."
>
>Well, my doc meant for me to take 2 tablets of Extra-Strength Tylenol.
>But if he meant megagrams... Hmm.. 1 Mg is 10^12 mg... So I need to take
>_2 TRILLION_ Tylenol Tablets... I don't even know if they make that much
>Tylenol in a year. If I swallow one every 10 seconds, it will take me
>about 230 million days or about 630 thousand years to finish the first
>dose of the prescription. Heck, I'll probably forget to call the doctor
>in the morning!
>
>And what's more, I've _seen_ medicines with the term "Mg" printed right
>on the label, yet I've been able to pick up the box, pay for it and carry
>it home. Maybe they have some sort of anti-gravity device hidden in the
>packaging. :-)
>
>Speaking for no one except myself,
>Joe Bachman
>jbac...@access.digex.net
>
Touche! I have seen Mg used for mg, too. But the point is that common
sense will prevent most of us from confusing the two.
+------------------------------------+
| John Tauxe jta...@aol.com |
+------------------------------------+
L. Joeseph Bachman
> In article <3u3sed$9...@stc06.ctd.ornl.gov>, John Tauxe <tau...@ornl.gov> writes:
> > I have a question for agricultural and water resources applications:
> >
> > In the USCS (US Customary System) we refer to large volumes of water in
> > acre-feet (AF), or thousand acre-feet (TAF). Here ar ORNL we are soing SI,
> > and I recently wrote some documents requiring these volumes. I chose the
> > cubic hectometer hm^3, which at forst sounds wacky, but is sort of like
> > a cubic hectare -- 100 m on a side. It is also a close conversion, since
> > 1 AF = 1.23 hm^3.
> >
> > What is the SI standard for this sort of thing?
> >
> > And flow: 1.0 MGD -> 1.12 TAF/y -> 1.38 hm^3/y
> > What would you do?
> >
>
> Geological Survey, 7th edition, p. 123, it would seem that either cubic meters
> or cubic hectometer would be a valid SI equivalent for acre-foot. Personally,
> I would use cubic meter, because it's a quantity that both I and my readership
> can relate to. I have no idea what "hecto" stands for without looking it up
> somewhere. I think it's reasonable to think that if a trained scientist like
> me, who knows something about SI units and "official" prefixes, has to look up
> the prefix, then my mixed audience of water-resources managers is going to
> think this stuff is total pedantic nonsense. Better to give them a unit that
> is likely to be familiar to them.
>
> Again, just my opinion. Generally, when I write stuff for water-resource
> management and regulatory agencies here in the US, I use US Customary Units,
> as these are most familiar and useful to the water resource managers and the
> general public.
>
> Conversion factors:
>
> To convert from to Multiply by:
>
> acre-feet cubic meter 1,233
> acre-foot cubic hectometer 0.001233
>
> cubic meter acre-foot 0.0008107
> cubic hectometer acre-foot 810.7
>
>
> Based on the note in Suggestions to Authors on p. 122, I also don't see why
> you couldn't use liters (or more likely millions or billions of liters) as
> well. Even reader with no scientific or technical background have probably
> purchased soda in 1 or 2 liter bottles. The only restriction, according to
> this source, is that the only prefix allowed with liters is "milli" (probably
> causing a great concern to all of those European winemakers who sell their
> product in 75 centiliter (cL) bottles), so you couldn't use "megaliter," but
> I wouldn't see any problems with "millions of liters per day" or "X 10^6
> liters."
>
> Joe Bachman
> jbac...@usgs.gov
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
Gerard Middleton
There is nothing wrong with cm except that it is not a _preferred_ SI unit.
SI advises that the commonly used units should all be multiples or
divisors of the basic unit by 1000 -- so m, mm, \mu m (micrometer);
of in the other direction km Mm...
Now, I have never seen anyone use Mm, but it is certainly OK in SI, and
so (presumably) is 1000 km, or even 123,4567 km if people feel more
comfortable that way.
As for the logic of SI -- there is none, except that it would save much
trouble if everyone in the world used the same system. SI is really the
ONLY possible candidate.
An imperfect analogy -- my first PC turned out to be compatible with
almost no others, though a very well engineered device. I rapidly learn
the lesson (also learned by those who bought Betamax video players) that
technical superiority is not what is important, ability to communicate
and use other people's products is. At present USA is like Mac people,
while the rest of the world are all IBM -- except that there really _may_
be some good reasons to stick with Mac.
Byron Bodo
>
>
> There is nothing wrong with cm except that it is not a _preferred_ SI unit.
>
> SI advises that the commonly used units should all be multiples or
> divisors of the basic unit by 1000 -- so m, mm, \mu m (micrometer);
> of in the other direction km Mm...
>
> Now, I have never seen anyone use Mm, but it is certainly OK in SI, and
> so (presumably) is 1000 km, or even 123,4567 km if people feel more
> comfortable that way.
>
Indeed. SI as it has been practiced in Canada and the rest of
the world has generally been fairly flexible, embracing
tonnes, cm, etc, as appropriate.
Have just waded through a mess of lake sediment -- geochronology
papers & every last one uses cm for the sediment section/layer
thicknesses.
The global biogeochem text I've been reading the past month
has 100+ tables & graphs cribbed pretty much verbatim from
source articles. A rough count shows about 1/2 the entries
showing mass use tonnes & the other 1/2 use most
every remaining conceivable SI mass unit including Mg.
It's difficult to imagine that much if any time was spent
squabbling about 'metrically correct' units.
Beyond the US borders it's not a big deal.
-bb
L. Joseph Bachman
>There is nothing wrong with cm except that it is not a _preferred_ SI unit.
Not only is there nothing wrong with the centimer, it's a very useful
measuring unit for measuring many common items in use in the home,
office, laboratory, etc.
>SI advises that the commonly used units should all be multiples or
>divisors of the basic unit by 1000 -- so m, mm, \mu m (micrometer);
>of in the other direction km Mm...
So, what is the reason for this "advice?" Who cares whether the unit
you're measuring with is a multiple/divisor of the basic unit by 1,000?
For many common measuring situations, that's too broad a range.
>Now, I have never seen anyone use Mm, but it is certainly OK in SI, and
>so (presumably) is 1000 km, or even 123,4567 km if people feel more
>comfortable that way.
But, obviously, people don't feel comfortable wit it, we have km, and
no larger units until we get to AU's, light-years, and parsecs (which I
don't think are SI units). The fact that people don't use the unit
surely says something.
>As for the logic of SI -- there is none, except that it would save much
>trouble if everyone in the world used the same system. SI is really the
>ONLY possible candidate.
I regularly use 3 measurement systems with little trouble -- the US
customary system, the cgs metric system and SI. I see no reason why SI
is the "ONLY possible candidate." Generations of scientists used cgs
metric, mks metric, and even US customary and British imperial units with
few problems. With the aid of a pocket calculator, I can quickly convert
from one system to the other. I also assure you that I do _not_ get
confused at all when I visit Canada :-).
>An imperfect analogy -- my first PC turned out to be compatible with
>almost no others, though a very well engineered device. I rapidly learn
>the lesson (also learned by those who bought Betamax video players) that
>technical superiority is not what is important, ability to communicate
>and use other people's products is. At present USA is like Mac people,
>while the rest of the world are all IBM -- except that there really _may_
>be some good reasons to stick with Mac.
Yes, but a cm is 100% compatible with 10 mm. The fact that people get
bent out of shape about the use of cm or cL is a problem with SI, not the
"metric system."
BTW, about 20 years ago, I was a hot propenent of having the USA covert
100% to the metric system. Now I'm not so sure, as the use of US
customary measurement units can be seen as an attempt by those of us in
the States to hold on to some cultural distinctiveness in an increasingly
homogenized world. Of course, most of our manufacturing is now done to
metric system standards, so we are compatible with the world where it counts.
Joe Bachman
jbac...@access.digex.net
Dr. Dick Dickson
>Indeed. SI as it has been practiced in Canada and the rest of
>the world has generally been fairly flexible, embracing
>tonnes, cm, etc, as appropriate.
<snip>
>The global biogeochem text I've been reading the past month
>has 100+ tables & graphs cribbed pretty much verbatim from
>source articles. A rough count shows about 1/2 the entries
>showing mass use tonnes & the other 1/2 use most
>every remaining conceivable SI mass unit including Mg.
Whoever wrote that book was lucky he or she wasn't publishing it for USGS.
They would make him or her redo all the tables and figures to be
consistent with USGS publication style, and make sure that all of the data
were expressed as valid SI units. The way I understnad it, all SI units
are built on the basis of meters, kilograms, and seconds. Named units
that are multiples of an SI units are restricted to multiples of 1000,
and the "official" prefixies are used on the base unit. No new unit
names are allowed for multiples. That's why it's "megagrams," and not
"metric tones," or "tonnes." You can use kilo, mega, giga, tera, or if you
need to get small, milli, micro, nano, pico. But no new names, so it's
"micrometer," not "micron."
>It's difficult to imagine that much if any time was spent
>squabbling about 'metrically correct' units.
I don't know about most countries, but in the US, the SI system is the
legal basis of measurement (even the US customary units are defined
relative to SI units.) So non-SI units are not legal :-). (caveat: I'm
not a lawyer. Check out Public Laws 94-268 and 100-418 ,as passed by the
U.S. Congress. Also National Bureau of Standards, or as it's now know,
NIST, Special Publication 330.) Thus, using units such as
"centimeters," "calories," and "tonnes" is the metric equivalent of
using "furlongs," or "grains per gallon." At least that's the view of SI.
>Beyond the US borders it's not a big deal.
What's commonly used in Canada and most of the world outside the US is the
"metric system" which is close to SI, but not exactly SI. Units such as
"metric tons", "tonnes", "centimeters," "cubic centimeters,"
"centiliters," "deciliters," "calories," "bars," "atmospheres," and so
forth are perfectly good units that have been used in the "metric
system," but are not valid units in SI.
I had a professor who told me many years ago that when they decided to
standardize the "metric system," there was a struggle between the
chemists and the physicists over whose units would form the basis for the
new standarized system. Apprently, the physicists won the debate, and
that's why the chemists had to change the units they worked with. For
example, I have and old (late 70's) physical cemistry text in which the
thermodynamic properties of various compounds were given in kilocalories
per mole, whereas newer texts give these properties in the SI units of
kilojoules per mole.
Personally, I'm closer to a chemist than a physicist, so I've never been
a big fan of SI. Many of the rules do seem a bit obsessive, and anyway,
I think that physcists are arrogant SOB's who think that their knowledge
gives them the ability to meddle in all forms of scientific
investigations. It has annoyed me to no end that they have shoved their
version of the "metric system" down everybody's throat.
As you can imagine, I was not hartbroken when they cancelled the SSC. :-)
It's OK, I'm a doctor!
Dr. Dick
Byron Bodo
>
>
Is it possible that in America the "Land of the Litigious", SI has
been given an excessive legal basis? All I got 20 yrs ago, was
a 2 page list of suggested units that were supposedly Canada's
version of SI. It included tonnes & cm, & gave no particular
status to multiples of 1000 of the base units. Things may have
changed a bit in 20 yrs, but I can't recall seeing any formal
edicts from our metricrats. Last time I looked about 10 years
back tonnes were still O.K. and in wide usage amongst federal
bureaucrats.
What we may indeed have is a general metric system that's been
mislabelled as SI, but so goes much of the world & without much
much fuss.
-bb