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From: TomGee on 21 Sep 2005 17:56 Yata yata yata. Total nonsupport for everything you said. Why should anyone take your opinion on this? If everything Encarta says is wrong, you are accusing eminent scientists of being stupid. Where does that leave you who claims to know more than they but who never gives anything more than your own opinion?
From: Randy Poe on 21 Sep 2005 19:39 TomGee wrote: > > > [...], then we can safely and simply assume > > > that my internal force is nothing more than the kinetic energy of the > > > body. If you are using the term "internal force" to mean "kinetic energy" then what you are saying is that "without kinetic energy, a body would not move". I can accept that, though it is vacuous, since to me "kinetic energy" is just the term for the energy which is stored in the motion. I guess you're also saying that if a body runs out of KE, it will stop moving. Again, that's a perfectly reasonable statement, though I would say that *by definition* a body which is not moving has no KE, and KE has no meaning apart from motion. And finally I guess you'd say that a body with KE will maintain a constant velocity forever if there are no external forces. And again I'd agree: if there are no external forces, KE is conserved, and so motion is unchanged. > > Force and energy can't be the same. They are of different dimension! > > > force and energy are not dimensions. They are OF different dimensions. They HAVE different dimensions. They are different things. That's why we don't like to use a word like "force" to describe a thing like KE which doesn't have the dimensions of force. The dimensions of force are mass times acceleration (mass x length/ time^2). The dimensions of energy are mass times velocity^2 (mass x length^2/time^2). Energy has the units of force times distance. > > > My model contends that energy is a force. Energy is not, of course, a force. Trying to equate energy to ma will lead to nonsense. Among other things, mixing up units inconsistently like that will cause answers to depend on the units you use. > > It's automatically rejected, out of hand. > > > By you and those who cannot see the forest for the trees. No, by trying to equate two non-comparable things. It's like saying "in my theory, area is age, and henceforth I will measure all real-estate properties in years, and if you disagree you're brainwashed. Can I sell you seventeen years of prime downtown property?" > > Force is a gradient of energy. > > > A gradient is a slope. How is force a slope of energy? It is the negative of the gradient with respect to position. In particular, where you have a sharp gradient in potential energy, you have a large force. For all interactions, the gradient of the potential energy function is the force. A very simple example: the gravitational potential energy close to the earth's surface is mgh, where h = height from the surface. The gradient of this is a vector of magnitude mg, pointing downward. > Gradient: physics measure of change: a measure of change in a physical > quantity such as temperature or pressure over a specified distance > Microsoft® Encarta® Reference Library 2005. © 1993-2004 Microsoft > Corporation. All rights reserved. Poorly stated, but at least Encarta didn't get it completely wrong that time. It has a more precise definition. It isn't just a "measure of change", it's a spatial derivative, a vector. And as you probably know, derivatives are not "over a specified distance" so Encarta got that part wrong. You really, REALLY need a better reference source. > Nothing in there about force being a measure of change in energy. You just looked up the definition of gradient. Did you expect to find a list of everything that is a gradient of something else? If I tell you velocity is the time derivative of distance, do you think that you will find velocity and distance listed under "derivative"? > > Put informally, force is a measure of how an energy (potential energy) > > changes with position. > > > You're just making that up, aren't you? Or else you're guessing. Neither. F = -grad V. > > Forces are interactions between objects. Internal forces exist only for > > composite bodies -- they are forces between the objects that make up the > > composite body. > > > I just bet that with a little encouragement you could make up a whole > new bunch of physical laws, no? Hint: the fact that you haven't seen these things doesn't mean they're new to the face of the earth, only new to you. They can be found in books. The derivative relationships between physical quantities won't be found in high school books. For those, you need a physics with calculus book such as is used in some college courses. Halliday and Resnick for instance. But I assure you such relationships are to be found in the standard texts. > > > A force is "power or strength: the power, strength, or energy that > > > somebody or > > > something possesses" > > > Microsoft® Encarta® Reference Library 2005. © 1993-2004 Microsoft > > > Corporation. All rights reserved. Not in physics. You really, REALLY, *REALLY* need a better reference than that. I suggest a physics book, ANY physics book, if you want information on physics. > > That's a layman's definition from a layman's reference. It's contradicted > > by even the most elementary of introductory physics references. Power is a > > rate of energy (has dimensions of energy over time). Force is a gradient of > > energy (has dimensions of energy over distance). > > > > > More made up definitions. Contradictions of authoritative sources <snort> Hint: No dictionary is an "authoritative source" for any technical term, and Encarta appears to be a less authoritative source than most dictionaries based on your quotes. > > It is perhaps the most fundamental facet of natural science that quantities > > with different dimensions can't be compared. It's meaningless to say > > they're the same, or equal. > > > Yet we compare the dimensions of length, depth, height, and time > everyday. Length, depth, and height are all lengths. Those are comparable. We can't compare force and energy, and we do *not* compare lengths and times. OK, I have a book which is 12" high here. And I've been sitting at this computer for 15 minutes. Can you tell me which is bigger, since you say such things are compared every day? - Randy
From: odin on 21 Sep 2005 19:51 If you are using the term "internal force" to mean "kinetic energy" then what you are saying is that "without kinetic energy, a body would not move". I can accept that, though it is vacuous, since to me "kinetic energy" is just the term for the energy which is stored in the motion. Don't try to help him make sense. Just plonk the fucker.
From: Randy Poe on 21 Sep 2005 20:14 odin wrote: > If you are using the term "internal force" to mean "kinetic > energy" then what you are saying is that "without kinetic > energy, a body would not move". I can accept that, though > it is vacuous, since to me "kinetic energy" is just the term > for the energy which is stored in the motion. > > Don't try to help him make sense. Just plonk the fucker. I love that he keeps quoting Microsoft Encarta as his authority. Is there anyone beyond the age of about 10, doing reports for school, who would consider using that as a source? - Randy
From: Herman Trivilino on 21 Sep 2005 20:21
"TomGee" <lvlus(a)hotmail.com> wrote ... >> What followed was NOT a description of an experiment. > Correct. It was a description of many experiments No, it was NOT a description of an experiment. > force and energy are not dimensions. Yes, they are. For example, the SI dimensions of force are newtons. The SI dimensions of energy are joules. Something that's measured in joules can't be the same as somethihng that's measured in newtons. > > Force is a gradient of energy. > A gradient is a slope. How is force a slope of energy? Sketch a graph of the potential energy versus the position. The slope will give you the magnitude of the force. > Gradient: physics measure of change: a measure of change in a physical > quantity such as temperature or pressure over a specified distance > Microsoft? Encarta? Reference Library 2005. ? 1993-2004 Microsoft > Corporation. All rights reserved. > Nothing in there about force being a measure of change in energy. Nope. You'd need a physics book for that. >> Put informally, force is a measure of how an energy (potential energy) >> changes with position. > >You're just making that up, aren't you? Or else you're guessing. No. And, no. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |