There is no CGPM resolution or BIPM position statement that I know of
that favors one of these three methods over the other two, unless by
the example of printed documents.
Gene,
I agree that there is no preference given in the standards for the use
of exponential notation over the use of raised dots (or spaces) and
solidi. I don't think that either Stan or I said there was any such
preference.
Jim
On 2014-12-17 12:47, mechtly, eugene a wrote:
Stan, Jim, and others,
I agree, raised dots to denote multiplication of unit symbols, and
solidi (slashes) to denote division of unit symbols are *optional*,
and may be represented by spaces, or by the explicit power (positive
or negative) of each respective unit symbol, as appropriate.
However, one must be careful to avoid the ambiguities (unspecified
sequence order of operations) of certain mixes of multiplications and
divisions of unit symbols.
I like the flexibility of being able to use any of these three methods
of expressing combinations of unit symbols in SI, without exclusion of
the other two methods.
There is no CGPM resolution or BIPM position statement that I know of
that favors one of these three methods over the other two, unless by
the example of printed documents.
Eugene Mechtly.
On Dec 17, 2014, at 9:10 AM, Stanislav Jakuba <[email protected]
<mailto:[email protected]>> wrote:
In due respect, Gene, there is no need for the alternative W.s as
there is no need for the N.m (for work) or the kg.m2/s2. Associating
any quantity with only one form of its unit represents a major
advantage of SI. Let's stick with it. The joule is the only form for
the unit of energy to be used in practice.
To those who commented on this email, and I thank you all, you should
know that the Editor "bought" the reasoning and plans the article for
the January issue.
Stan Jakuba
PS: While on this topic, the above principle applies also to the
quantity "energy consumption" that is universally expressed, wrongly,
as Btu/day, MWh/year, etc. In the spirit of SI, the ONLY unit for
power is the W. And because energy consumption is a flow, the unit of
power (W) is correct here despite the almost universal, worldwide
opposition. Imagine that "... per day, per year, per hour, per
minute, per decade ..." all gone with the watt. Suddenly all
statistics are comparable directly.
On Mon, Dec 15, 2014 at 11:58 AM, mechtly, eugene a
<[email protected] <mailto:[email protected]>> wrote:
Stan,
The “joule” of energy equals exactly one “watt.second”; the
product of the watt and the second, where all reasonably literate
persons have heard of the watt and the second,
and might even know that the watt of power is *defined* as one
joule per second for the time rate of energy processing or transfer.
Try using the watt.second (Ws or W.s) in your writings, until
your readers are more familiar with the joule.
Gene Mechtly.
On Dec 15, 2014, at 8:17 AM, Stanislav Jakuba <[email protected]
<mailto:[email protected]>> wrote:
*USMA members will, I hope, be pleased reading the answer to an
editor who desired that American units be presented alongside
the SI values in my manuscript. *
*
*
*Dear ....*
*I attempted the parenthesis you suggested but found the
resulting complexity of the text disruptive and harder to read.
And there are other problems associated with doubling each
unit. Allow me a few words of explanation.*
**
*The article is about comparing two sets of numbers. For that,
there need not be any unit at all. The majority of readers will
skip the units anyway, and the few curious engineers and physics
teachers will know how to convert to whatever units they like.
As to the several common values I doubt that there are readers
that wouldn't know that water freezes at 0 deg. Celsius or what
a km is. As to the substitution for the one still unfamiliar
unit – the joule or MJ – here Americans use several different
units for energy such as calorie, Btu, kilowatt hour, lb-ft. As
a result. I am at a loss which one to select. Different
professions** use them all – that would be four parentheses.
Instead, I spelled out the symbol MJ and use it consistently
thereafter. Thus no problem with comparing numbers. In any case
non-technical readers will not care, and experts who might be
checking the math will convert the value to whichever unit they
like. I am pleased to say that, up to now, **no publisher asked
me to add conversions. Dozens of articles, no complains. May I
say that one might underestimate one’s readers?*
**
*As a side issue, you may be interested in why I insist on the
units of a system that has only one unit for any measurement, be
it energy, power, or length. That’s because, with the
multiplicity of the U.S. energy and power units, it is common to
present false or misleading numbers and get away with it for it
is too difficult and bothersome for readers to look up all the
conversion factors to check. I might also point out that since
it is the Federal Law and Exec. Order that state that "SI metric
is the preferred measurement system in the **U.S.**" my writing
in SI only should help citizens learning it. Once they see how
**easy comparisons are with SI units, they might actually prefer
that system particularly when noticing the cheating in the daily
press with American units such as the one illustrated in the
other enclosed treatise. *
*Yours,*
*Stan Jakuba*
**
