Dear Jim,
Thanks for the reference to a 'baker's dozen'. I had been meaning to
look this up for some time but had not quite got around to it.
You might find this interesting:
http://www.phrases.org.uk/meanings/Bakers%20dozen.html
I was also interested in the reference to the two kings, Henry II and
Henry III as these lived at a time when there seemed to be a burst of
activity on the issue of honest measures in trading.
Cheers,
Pat Naughtin
Geelong, Australia
On 2008/12/17, at 1:47 PM, James Frysinger wrote:
De-rating a product is not at all uncommon. It provides a cushion or
safety factor with respect to the claims made to sell it.
Overfilling packaged goods is another example of this practice. Even
our folklore remarks on this with "a baker's dozen", which is 13
items.
Jim
Pat Naughtin wrote:
Dear Stan,
Thanks for this article. I enjoyed reading it and I particularly
enjoyed your explanation of torque as I am not an engineer and the
diagram of the horse.
As I read your article, two thoughts occurred to me.
1 I recall my first physics teacher telling me that Watt lifted a
weight vertically in a well using the windlass on the well to
translate the vertical force of the weight to the dragline attached
to the horse's harness. Either way, it would produce the same
effect but with one less pulley.
2 The same physics teacher told us that James Watt also cheated
when calculating the 'power rating' of his horses by understating
the size of a horsepower. The story was that Watt chose the largest
strongest (most powerful) horses that he could find and used these
for his tests. He then rounded down their performance from (say)
590 to 550 foot pound per second. The idea behind this subterfuge
was that he was sure that after he had sold and installed a one
horsepower engine he would be barely out the gate before the new
owner would try out his new steam engine against a real horse. I am
sure that subterfuges such as this were quite common prior to the
international standardisation made possible by the introduction of
the International System of Units (SI). Watt might have been unique
in the creation of the horsepower in that he did it for an
relatively honest reason rather than for cheating and/or obfuscation.
Cheers,
Pat Naughtin
Geelong, Australia
On 2008/12/12, at 1:13 AM, Stan Jakuba wrote:
I am responding to Pat's challenge to help with the explanation of
power, that is power measured in W (not in votes, for example, as
might apply to political power). There are numerous attachments
in these e-mails, arranged to facilitate their opening.
The first group is a scanned article that illustrates the meaning
of mechanical power and of work (as a form of energy). It also
covers torque (it is in the title) thereby touching on the other
topic frequent on this forum - why N·m is a unit of torque
(couple) as is, but N·m as work is called J.
The second one compares power and energy in nutrition and in
workouts. It has been presented on this forum many times. To
obtain the feel for W and J, read the last footnotes.
The next one is a table of food energy (heat) intake and power
output in bicycling and in walking. In the footnotes it covers
some terminology issues, and shows that men's metabolic-to-output
efficiency is on par with any comparably-sized combustion engine,
zoological or mechanical. The table has also been presented here
before.
The last one is a table similar to the preceding one. It presents
several physical activities and shows when power in W equals
numerically energy in kJ. It had also been here before.
While at this, I just thought that you might want to check you
knowledge. Thus the last attachment. I will be glad to check
anyone's answers and provide corrections, if needed. Refer to the
question numbers.
Stan Jakuba
----- Original Message -----
*From:* Pat Naughtin <mailto:[email protected]>
*To:* U.S. Metric Association <mailto:[email protected]>
*Cc:* U.S. Metric Association <mailto:[email protected]>
*Sent:* 08 Dec 03, Wednesday 00:19
*Subject:* [USMA:42118] Re: Problems with power
Dear Bill and Jesse,
First, thank you Bill for responding to Jesse's question. I have
to admit that I ducked when he first proposed it as I have always
found it difficult to explain the difference between energy and
power. I was hoping that someone more knowledgeable about physics
would jump in. I particularly like Bill's line: /power is
instantaneous; energy requires time (even if that time is only a
picosecond)/ as better than the usual dull definitions:
Energy is the ability to do work.
Power is the time rate of doing work or of using energy.
By the way, as I was searching for a better answer to Jesse's
question, I came across two interesting web sites. The first is
the USA Government Web
at http://www.usa.gov/Citizen/Topics/Environment_Agriculture/Energy.shtml
where
I found tutorials such as
this http://www.glenbrook.k12.il.us/gbssci/phys/Class/energy/u5l1a.html
but
I was not happy that these explained in suitable terms an answer
to Jesse's initial question. However, I soon became confused by
the diversity of measuring words used on this web site. As you
know I have found some 199 different words to describe energy
(requiring 39 402 conversion factors) with old pre-metric
measures, when only 1 unit is needed for the metric system (with
no conversion factors at all);
see http://www.metricationmatters.com/docs/EnergyWords.pdf
On the way, I found this interesting comparison of energy
sources http://physics.syr.edu/courses/modules/ENERGY/ENERGY_POLICY/tables.html
although
I was disappointed in the muddled old pre-metric measures placed
in with the correct use of SI units.
Cheers,
Pat Naughtin
P.S. I shall mull some more!
On 2008/12/03, at 3:16 PM, Bill Potts wrote:
I agree with you Jesse.
5 W represents power and 5 J represents the energy used by a 5 W
device in 1
s.
Put another way, power is instantaneous; energy requires time
(even if that
time is only a picosecond).
Bill
________________________________
Bill Potts
WFP Consulting
Roseville, CA
http://metric1.org [SI Navigator]
-----Original Message-----
From: [email protected]
<mailto:[email protected]> [mailto:[email protected]
]
On Behalf
Of Ziser, Jesse
Sent: Tuesday, December 02, 2008 17:45
To: U.S. Metric Association
Subject: [USMA:42115] Re: Problems with power
--- Pat Naughtin <[email protected]
<mailto:[email protected]>> wrote:
supply the power needed - supply the energy needed (Again a
difficult idea as the engineers have to provide an
electrical plant with a
power rating that will provide the maximum amount of
energy needed at a particular time)
This in particular illustrates the problem I have with your use
of the term.
It sounds like
you're saying that a phrase like "supply the 5 watts of power
needed by the
motor" is incorrect
and it should be "supply the 5 watts of energy needed by the
motor". Is
that what you're saying? Because this conflicts with the
definition of the term "power" as
I learned
it in school.
And a power rating specifying the amount of energy needed at one
time? Well
that's just gibberish
to me.
Please explain in more detail why you think these uses of
"power"
should be
changed. I am
confused.
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that
they now save thousands each year when buying, processing, or
selling for their businesses. Pat provides services and resources
for many different trades, crafts, and professions for commercial,
industrial and government metrication leaders in Asia, Europe, and
in the USA. Pat's clients include the Australian Government,
Google, NASA, NIST, and the metric associations of Canada, the UK,
and the USA. See http://www.metricationmatters.com <http://www.metricationmatters.com/
>for more metrication information, contact Pat at [email protected]
<mailto:[email protected]> or to get the free '/
Metrication matters/' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
their businesses. Pat provides services and resources for many
different trades, crafts, and professions for commercial, industrial
and government metrication leaders in Asia, Europe, and in the USA.
Pat's clients include the Australian Government, Google, NASA, NIST,
and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com
for more metrication information, contact Pat at [email protected]
or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
