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From: TomGee on 21 Sep 2005 23:20 Randy Poe wrote: > 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. > > No, I am not saying that. I am saying that the isolated object moves using the energy of its mass to move. There are no bodies without energy visible to us and all mass contains relatively vast amounts of energy. A moving body has energy due to its motion in addition to the energy in its mass. The total energy of a mass is measurable as momentum and it can be applied as a force as well, as in the 3rd law of inertial motion. Thus, momentum is both a measurement and a force, like it or not. > > > I guess you're also saying that if a body runs out of KE, it > will stop moving. > > Not quite. It need not be KE, as we're really talking about the potential energy in a body which becomes kinetic energy as it is used. > > > 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. > > Yes, I agree. > > > 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. > > Oh, wonderful. I am surprised, but elated too at having been able to get my point across to you. However, I would not say the constant velocity can be maintained forever. Remember, "Any system will run down when left to itself, through various forms of attrition." The body will eventually run out of the energy it has due to its motion, i.e., its momentum, and probably then something would change in its velocity. I have no idea what may happen to it then. > > > > > 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. > > Yes, we don't like to use force in that way, I agree, but we need to understand that our division of things can make better sense sometime if we combine what we know about them. Work and energy is measured in ergs. Thermodynamics shows that heat, work, and energy are equivalent in that one calorie (the unit by which heat was measured way back then) is equivalent to 4.186 x 10^7 ergs. > > 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. > > Yes, that's true. But we know energy comes in various forms and can be measured in various ways. My model contends that energy is the fifth force and that as such it will be the cornerstone of the GUT as it is common to the other four fundamental forces. It is time for man to get out of the box, stop dividing everything, and start combining what we know individually of all things. The first division item we must dump is this silly obstacle of the division of things which we often use as one and the same thing. We have come a long way in that but there is still work to be done on it. > > > > > > 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. > > Is that what you thought about mass and energy? Were you one of those who would burn at the stake anyone claiming that mass and energy are equivalent? And now that everyone agrees with that, are you now saying the same thing about energy and force. Let's examine the possibility that my wish to unite the two could work. Here is a brief (but long) excerpt from my essay, "The Time And Motion Relationship" (by Thomas Garcia copyright 1996): How is it possible for waves to move through a medium without the media having to travel along with it? We know the answer to that. Waves are a disturbance that transfers energy progressively in a medium, and that may take the form of an elastic deformation or of a variation of pressure, electric or magnetic intensity, electric potential, or temperature. Thus waves - any waves - are a progressive transfer of energy through a medium whenever such en-ergy is created by a causative event. The next question for us, then, should be: How and when does such transfer of energy occur? The answer to that is not really as difficult as it may seem. Energy is commonly de-fined as the capacity of matter to perform work, as a consequence of its motion or position in relation to forces acting upon it. Yet, energy is also defined as usable power, as a vigorous exertion of power, and as a synonym for power. Other synonyms for energy are force, strength, and might. Power is ordinarily defined as the time rate at which work is done, but it is also defined as the ability to act or produce an effect, and it implies possession of the ability to wield force. Therefore, energy is a force having the power to overcome resistance to it. A force is ordinarily defined as any action or influence that when applied to a free body results sometimes in an acceleration of the body and sometimes in elastic deformation and/or other effects. Newton's second law of motion states that the amount of acceleration imposed on an object times the mass of the object is equal to the net force acting on the object. We may argue that particular law refers only to objects, but a force is also described as the influ-ence of a field, such as electrical and gravitational fields. A force acting at an atomic level is known in high-energy physics as an interaction. So-called elementary particles exert forces on each other and the imposition of such forces are called interactions. In spite of all the defini-tions above that lead to the conclusion that energy is a force, I have met with solid opposition against such a claim from some knowledgeable Internet users who post on physics news-groups. They seem unwilling to accept the obvious, probably because there already exist four other well-explained "forces of nature." I have heard no one seriously suggest that energy could be a fifth force. That could be because all four forces use energy as their motive power. They use it in different ways, but it is energy they use, nevertheless. Even the so-called messenger, or "signal" particles must ac-complish their "work," or, "interactions," through the use of energy. One would think that the concept of energy as a force could easily be accepted on the basis alone that it is the one force which is common to all the other forces and if so, it may be that it is also the central factor of the GUT of the universe and essential to the TOE. Clifford E. Swartz writes in "Mechanics," in an article for Microsoft Encarta Encyclopedia 99: "The quantity called energy ties together all branches of physics. In...mechanics, energy must be provided to do work;.... Many other forms of energy exist: electric and magnetic potential energy; kinetic energy; energy stored in compressed springs, compressed gases, or molecular bonds; thermal energy; and mass itself."18 > Among other things, mixing up units inconsistently like that > will cause answers to depend on the units you use. > > I am not mixing up units, I am using terms well-accepted in their application and combining their common usage. > > > > > 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?" > > If I were doing that, you would be correct in saying that. > > > > > 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. > > Yes, we have a large force which is not being applied, so it is a potential force the same as it is a potential energy. > > > 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. > > No I don't. You allow yourself to do what I'm trying to convince you to let me do, but you don't allow me to do it. so long as you don't want to combine mass and energy you will find some way to object to it, even though everyone accepts the combination. It's okay for you to combine terms but when I do it, my source is not acceptable unless it fits your definitions. When you attack Encarta you are attacking well-known authorities in the field whom Microsoft has paid well to write for them. Even if they volunteered the information, they have their reputations to defend so they would not write anything about which they may have some doubts or lack of knowledge. To rag any source except wiki wiki only makes you look like a know-it-all esp. when you offer no support for your opinions. Wiki wiki is different because is can be edited by anyone and so it cannot be considered as reliable as a work which is competitive with the highest authorities in a field. I don't believe Encarta is error-free. I have found some things in it I think lack clarity. But then I find the same in other works too. > > > > 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. > > Um, you do not know Encarta is an encyclopedia, as compare to a dictionary? > > > > > 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: Matthew Lybanon on 21 Sep 2005 23:31 in article 1127359246.581977.318390(a)g49g2000cwa.googlegroups.com, TomGee at lvlus(a)hotmail.com wrote on 9/21/05 10:20 PM: .. . . > Um, you do not know Encarta is an encyclopedia, as compare to a > dictionary? But it was still wrong.
From: Timo Nieminen on 22 Sep 2005 00:13 On Thu, 21 Sep 2005, TomGee wrote: > Timo Nieminen wrote: > > > > Newton says if there is no force, there is no change in the state of > > motion. If there is no change in the state of motion, how can the object > > stop? > > > No, Newton does not say that. That's what they told us he said, but > it's a lie. How can you say that it's a lie, and then basically agree: > He said that without an external force applying to it, an > object will move in a straight line at a uniform motion. Yes, so if there is no external force, the object will move in a straight line in uniform motion. That means that if there is no external force, the speed doesn't change. That means that an _external force_ is _required_ to stop the motion. [cut] > That's my whole point: The translations are actually wrong in claiming > that Newton said an isolated body continues its motion without any > force external or internal applying to the object. If that's your whole point, you should learn Latin, and read the original. If you doubt the translations, read what Newton wrote in the original Latin. And do read Newton's definitions. Especially his definition of force. Read definitions III and IV, and Newton's commentary. You will notice that Newton's "vis insita"/"Vis Inertiae" is called "inertial mass" in modern English physics terminology. Now, "vis insita" can be translated as "innate force", but you should be careful with that terminology since it is not the same as "force" in modern physics. You might also happen to notice that Newton states in his commentary that "vis insita" is the "inertness of the mass" only, and is careful to state that "vis insita" is _not_ a force to the body, but a "force" exerted _by_ the body to resist and external applied force. Thus, in the absence of an external applied force, the "vis insita" does not act. "Vis impressa", as defined in def IV, is what is called "force" in modern physics terminology. Now, if you wish to argue that "vis inertiae" is the "internal force" that sustains motion, (a) this is not "force" as the term is used in modern physics, (b) it is the same as saying that "mass" is the "internal force" that sustains motion, and (c) calling "inertia" a "force" might change the name, but won't change the physics. Newton's statement that, in your words: > without an external force applying to it, an > object will move in a straight line at a uniform motion. still means that an external force ("vis impressa") is _required_ to stop motion. And you might be interested to read Newton's commentary on def V, containing as it does the claim that in the absence of external forces, an object will proceed in its motion "in infinitum". -- Timo
From: PD on 22 Sep 2005 00:31 TomGee wrote: > 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? The definition of a perputual motion machine as Encarta defines it is in conflict with the definition of a perpetual motion machine as almost any reputable physics book would define it. A number of references from reputable physics books would demonstrate that. The fact remains, however, that TomGee has already stated that a very large number of references written by eminent physicists would not be enough to convince him, as those would be all unsupported opinion (in his judgement). He has already demonstrated that he would rather trust Encarta's unsupported definitions, as he considers them to be written by eminent scientists, also an unsupported claim, and he considers those authors to have higher eminence (also an unsupported claim) than the authors of the physics books. PD
From: Eric Gisse on 22 Sep 2005 00:37
Schoenfeld wrote: [snip] > > s(t) = SUM{n=0}^+INF [ s^n(0) t^n / n! ] > > Your assumption that dg/dt = 0 reduces s(t) to: > s(t) = s(0) + s'(0)t + 1/2 s''(0)t^2 > > > Much simpler. I derived the solution, you reverse-engineered the solution from an arbitrary equation. > > > > > > > Don |