Of course, John, *time rate* of energy (J/s) (of production, transfer, or conversion to other forms including heat) is not energy (J).
I did get your point! Your concern is confusion of the quantities power and energy, not a particular numerical value. But if you do quote a value, it should be in SI (my point). Please forgive me for misspelling your name. I'll try to remember it is Steele. Gene. ---- Original message ---- >Date: Wed, 9 Jun 2010 07:34:16 -0700 (PDT) >From: "John M. Steele" <[email protected]> >Subject: [USMA:47606] Re: One unit only >To: "U.S. Metric Association" <[email protected]> > > The point is NOT the 15000. > > The point is that BTU/h != BTU > Power != energy > > Watts != joules > > Here "!=" is used in the computer language sense of > "not equal" > > Stating the incorrectness of the label (power vs. > energy confusion) is the entire point of the > reference. > > ------------------------------------------------ > > From: "[email protected]" <[email protected]> > To: U.S. Metric Association <[email protected]> > Sent: Wed, June 9, 2010 10:05:33 AM > Subject: [USMA:47602] Re: One unit only > > If the SI rating is merely incidental, why even > state the non-SI rating. Is the non-SI rating more > than incidental? > > Again, why burden the readers with the numerical > conversion of the rating, accurate or only orally > approximate? > > ---- Original message ---- > >Date: Wed, 9 Jun 2010 06:38:19 -0700 (PDT) > >From: "John M. Steele" > <[email protected]> > >Subject: Re: [USMA:47590] Re: One unit only > >To: [email protected], "U.S. Metric Association" > <[email protected]> > > > > Obviously, there may be alternatives to my > > viewpoint, but I felt the SI rating was > incidental > > to the conversation when the real issue is that > the > > label is completely wrong and contributes to the > > confusing of power and energy. > > > > Of course, the BTU is as poorly and multiply > defined > > as the calorie. Pick a BTU, pick any BTU! > However, > > I would hazard a professional SWAG that the > rating > > relates to a fuel rating and an API method, > > therefore BTU60, the value at 15.5555 °C (60 > °F), > > which is 1054.68 J/BTU. Of course 1 h = 3600 s, > so > > 15000 BTU/h x 1054.68 J/BTU x 1 h/3600 s = about > > 4400 W (4394.5 W if you like "decimal dust"). > > > > Any other BTU would only change the result > > slightly. For practical accuracy just multiply > the > > BTU/h value by 0.293 to get watts (in your head, > > even 0.3 would suffice) > > > > > ------------------------------------------------ > > > > From: "[email protected]" > <[email protected]> > > To: U.S. Metric Association <[email protected]> > > Sent: Wed, June 9, 2010 9:07:13 AM > > Subject: [USMA:47590] Re: One unit only > > > > John, > > Although you may be forgiven(?) for quoting Jim's > > non-SI value, you too do not include the power of > > the gas grill in watts. What is it? Why burden > the > > readers to convert to SI? > > Gene > > p.s. I do have highest regard for the postings of > > both of you relative to postings by other > > subscribers in spite of this rare deviation from > SI. > > ---- Original message ---- > > >Date: Tue, 8 Jun 2010 18:59:49 -0700 (PDT) > > >From: "John M. Steele" > > <[email protected]> > > >Subject: [USMA:47581] Re: One unit only > > >To: "U.S. Metric Association" > <[email protected]> > > >Cc: "U.S. Metric Association" > <[email protected]> > > > > > > Jim, > > > > > > I agree with glassy-eyed and wobbly kneed, but > > this > > > is the ROOT of all energy vs power confusion. > > > > > > Just ask, "So, after the grill has consumed > 15000 > > > BTU, it dies? That seems like a lot of money > for > > a > > > grill with a one hour life." > > > > > > I'm afraid it is up to the engineers to be > > > persistent PITAs on this matter. Proud to > serve. > > :) > > > > > > > > ------------------------------------------------ > > > > > > From: James R. Frysinger > <[email protected]> > > > To: [email protected] > > > Cc: U.S. Metric Association > <[email protected]> > > > Sent: Tue, June 8, 2010 9:47:38 PM > > > Subject: Re: [USMA:47579] Re: One unit only > > > John, your last paragraph can be exemplified > with > > > the ratings that one sees posted for gas > grills. > > > They are usually rated as being, for example, > "15 > > > 000 BTU". What is meant, though, is "15 000 > > Btu/h" > > > -- where I have fixed the error in the symbol > and > > > have added the divisor. The former is an > energy > > > value; the latter is a power value (the rate > at > > > which chemical energy is converted to thermal > > > energy). > > > > > > Caution: Experience has shown that if I try to > > > discuss this with the sales staff, they get > > > glassy-eyed and start to look wobbly in the > > knees. > > > > > > Jim > > > > > > John M. Steele wrote: > > > > Pat, > > > > I'm sorry but I must go back to your > statement > > to > > > Stan, " It seems really odd to me that > engineers, > > > who > > > > > probably know much better, are using a > > power > > > unit > > > > > when they are referring to energy." > > > > In the instance you cite, you are talking > > about > > > energy over a time period, and energy divided > by > > > time is power. Annual energy usage has a > > dimension > > > of power, whether you use power units (watts) > or > > > explicitly describe the energy and the time > > period. > > > > Stan is at least technically correct in > using > > > watts. I have some misgivings about average > > power > > > vs peak power if the situation is not fully > > > explained. > > > > Power and energy have exactly the same > > > relationship between them as velocity and > > distance. > > > If either is described fully as a time > function, > > I > > > can derive the other. Since I am retired, I > > drive > > > much less. Pardon the miles, but they are > > > unfortunately the units on my odometer. I am > > only > > > driving 4000 - 4500 miles per year. As there > are > > > 8760 hours in a common year, my average speed > is > > > circa 0.5 MPH. That, of course is completely > > > useless as a description of my driving which > is > > > normally at 25 - 75 MPH, plus many hours with > the > > > ignition is off. My miles per annum is a > speed > > > (just not terrible useful). 0.5 MPH or 4400 > > > miles/annum encodes the same information. > > > > In the same sense 1600 PJ/annum and 50.7 GW > > > encode the same information. As I don't know > how > > > evenly the 1600 PJ of coal is burnt over the > > year, > > > the utility of average power may be debatable > but > > it > > > is technically correct. When energy usage > over a > > > period is described, the period is so > intimately > > > attached to the energy that it would be better > to > > > drop both units than only one. > > > > I do understand that you meant petajoules > per > > > annum, but I believe that omitting the per > annum > > has > > > lead to some of the confusion that has existed > > here > > > in various notes about energy vs. power. It > must > > be > > > completely explicit, or at least that is my > view > > on > > > the matter. > > > >...
