where does the power go?

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Chris Smith
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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 5:00 pm

Some of us learn our history, some of us don’t. Some of us have degrees in mechanical engineering and the ones that don’t seem to want to set the pace. <p>How foolish of me, they with out the degree know things that I don’t? <p>Like how to guess it wrong, and argue, and deny, and piss and moan.<p> Ill stick to the facts and the history. <p>For the record and what’s in the history books, James Watt took a guess at the work done by a horse and guesstimated it to be the figures we still use today.<p> These factors have made up the world of torque and Horse power for the last three hundred years. <p>But if this piece of history or these facts elude you or confuse you, feel free to change them into any term that you can handle. Other wise, stop arguing with the history books and Facts, it sounds like your whining. <p>And for the record, that why a formal education trumps a guess any day.

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Re: where does the power go?

Post by Robert Reed » Sun Sep 18, 2005 5:08 pm

Chris
After reading your last reply, would this be correct to condense it into a nutshell : ???
Pounds-feet is "Static Force"
Foot-Pounds is "Dynamic Force"

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Chris Smith
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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 5:29 pm

That’s close Robert.<p>The “foot pound” is more of a colloquial term derived over the years, and applied loosely to the form of work that we have used in modern times and ways. <p>A inaccurate expression because you cant have 100 feet, and one pound of force, and call it a accurate term.<p> The last few posts back, the electrical term for work described it best, loosely but accurately.<p> We can "reel in" 100 foot of cable over a one foot wheel diamater, with a torque factor of X, and then claim it to be Feet pounds as in “Feet times X pounds times 100 foot of distance distance” for a total equation. <p> This isn’t however a physics or engineering standard. <p>The term coined from James Watt stated how many pounds of force, specifically against a one foot radius, and with time added in was equal to a unit called the Horse power or portion there of.<p>To reverse this role and say, how many feet, against a pound of force, simply does not equate to the same thing. And to say "well we know what it means, or that it really is the same thing", is also incorrect. <p>The foot pound will remain a misnomer, used well and often, but just a misnomer.

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Re: where does the power go?

Post by josmith » Sun Sep 18, 2005 5:49 pm

"A inaccurate expression because you cant have 100 feet, and one pound of force, and call it a accurate term."<p>What makes this inaccurate? One pound of force acting over a given distance sounds precise and repeatable to me.

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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 5:53 pm

100 pounds and one foot are not the same as 100 feet and one pound, and thats why its called the Pound foot, after James Watt meant it to be. <p>Work can be “described by” any colloquial term one wishes to chose.<p> My yard cost twenty bucks and three Mexicans two hours, to do the work.<p> It took three ham sandwiches to get the energy to climb a mountain, and that too is work. <p>These are colloquial terms and uses describing the job done. <p>MY Calories, or work hours to pay off some one else, who burned the calories to get the job done. This is work. <p>If mechanics, physics, or engineering were to rate these same jobs, the Pound foot or Joule, HP, Watt, or the calorie would be used, and not back wards. <p>Even the foot pound term used to described a 100 foot reel of wire rope over a three inch pulley lifting a 230 kilo gram object in one minute can be converted into the proper rating of Pound /Foot or horse power or watt or joule.

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Re: where does the power go?

Post by josmith » Sun Sep 18, 2005 6:28 pm

"100 pounds and one foot are not the same as 100 feet and one pound, and thats why its called the Pound foot, after James Watt meant it to be."<p>They are the same in that both situations define the same quantity of energy.

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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 6:47 pm

Is that what your physics teacher taught you Joe, or is it just a big guess from the peanut gallery?<p>Im GUESSING it’s the latter. <p>I can name one physics factor that get in your way, I mean it gets in the way of your guess. <p>Can you name what factor screws up your equation?

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Re: where does the power go?

Post by josmith » Sun Sep 18, 2005 7:01 pm

So you are saying that they don't define the same amount of energy? How so?

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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 7:25 pm

"To Define" the work "done" is not the same as the actions that it takes to achieve those actions. Quantitatively speaking both are the same. [static-work-done, mathematically so after the fact]<p>100 pound / foot and 100 foot pounds in a static mode of work already done are the same. <p>However, in real life work done is always followed by a real action, a real time frame, and a real exercise on how to get it done. <p>When your "working" the real world, you can not ignore the other factors that come into play. <p>Mass, momentum, and acceleration are once again part of the WHOLE picture. <p>So if you think you can accelerate a 100 foot pole with a weight on it, just as fast as you can accelerate a one foot pole, with equal and opposite of numbers to make the equation the same, Good luck. <p>Hence the reason and formation of the exact science called physics, and the exact terms they use.<p> They are not approximate, they are not “close enough” and each one of them has no approximation to another term. <p>Each term builds on another to form a third. <p>Each term defines a specific exact meaning, and these meanings are not “transferable or approximate to another”. <p>They are exact in their defining points for a unconfused reason. <p>Chaos is not what physics is about, and pretending the foot pound and the pound foot are the same is just a small part of that chaos.

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Re: where does the power go?

Post by josmith » Sun Sep 18, 2005 8:01 pm

Foot pounds and pound feet can be confusing although they are clearly defined. I wouldn't use either one without adding the words "of energy" or "of torque" after them for reinforcement.
I don't see how you get from a failure of the English language to "chaos"
The real world can be defined by theory. It's a mater of how precise the model needs to be. More precision requires more factors to be included.

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Re: where does the power go?

Post by Chris Smith » Sun Sep 18, 2005 8:14 pm

Yes joe that is my point. <p>You cant flip terms and say they are the same. <p>James Watt knew that a measurement needed to be applied, and so he set a standard. <p>That standard is not interchangeable with another. <p>But rather each term has its exact meaning, and for a reason. <p>The minute you flip flop from one to the other your not including other factors, and thus the end result will be chaos, as far as a reproducible scenario. <p>If I sent you the result in Foot pounds, and you tried to guess that I used Pounds feet, your experiment would most likely fail. <p>This is why we use exact terms, so there is no chaos in the results.

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Re: where does the power go?

Post by terri » Mon Sep 19, 2005 5:18 am

So if I say, "746 Watts," what do I mean in mechanical terms?<p>And is it dyne-cm or cm-dyne per second?
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Re: where does the power go?

Post by Chris Smith » Mon Sep 19, 2005 9:38 am

746 watts of potential is the “same as” or “equal to” 550 pounds /feet of potential. [stored energy] <p>That’s 550 pounds of weight, and one foot of leverage, not 550 feet of fall or length using a one pound object. <p>And this “implies” all of the other “standard” factors of physics for stored energy.<p>This does not “dictate” that you must use these standards. <p>If you incorporate time or levers out side the norm, you are doing so in a “non standard” fashion and your NEW formulae will reflect this fact. <p>This include all the laws of physics, friction, mass, momentum, and acceleration all of which is how the figure was arrived at in the first place to create a “standard”. <p>Add or subtract any other formulae, rule, or applications out of the standard and you form a different equation such as the “Foot pounds” which relates to “Work” but does not state how that work was done in a “standard format” or rule. It merely states a accumulated amount of work has been done.<p>The Newton meter is the SI, the dyne centimeter is the Erg, and the Pound Foot is the British units for the "system[s] unit of work".<p>[ September 19, 2005: Message edited by: Chris Smith ]</p>

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Re: where does the power go?

Post by terri » Mon Sep 19, 2005 10:41 am

OK, I'll go along with the car ads which quote torque in pound-feet lately. I'll try to remember this.<p>So the story about the furlong-stone per fortnight measure of power, which I'm fond of quoting, is incorrect, I guess.<p>It should be stone-furlong per fortnight.<p>[ September 19, 2005: Message edited by: terri ]</p>
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Re: where does the power go?

Post by Chris Smith » Mon Sep 19, 2005 11:35 am

As long as you use the 14 pounds and the 14 days in the right context, it should work out?<p>But 660 feet of torque radius?<p>[ September 19, 2005: Message edited by: Chris Smith ]</p>

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