Motion
in [Physics]
|
Prev: Free fall
Next: 50% OF POPULATION BELOW AVG IQ!
From: Randy Poe on 26 Sep 2005 21:18 TomGee wrote: > Randy Poe wrote: > > It is a model telling you how the two things called force > > and momentum are related. The equation doesn't cause this > > relationship, but it is a relationship which is true. > > > > > Still, it does not tell you what you imagined it did. It doesn't? Not having your telepathic powers, I don't know what you mean. What did I imagine it told me and why doesn't it tell me that? > Equation, model, > math construct, whatever, it simply states what a force is equal to in > this particular case. All else you imagine it tells you is just that - > imaginary. It does not imply that in the sense it is a necessary > condition for the equation to hold. You can infer what you will from > what it says, but at best an inference is still just a guess. Something I deduce mathematically from the equation F = dp/dt, something that can be derived in clear, unambiguous, deductive steps, is not what we normally term a "guess". Tell you what. Why don't you ask me a question you think I can't answer from F = dp/dt? > > Mass can be viewed as frozen energy, > > > Not according to the formula; No. The mathematical formulas in physics are not the physics, they are merely one component of it. The physics postulates are what gives meaning to the symbols in those equations. For instance, in F = dp/dt, the principle which we have used since Newton's time is that, without exception, a time-changing momentum can only arise as a result of a force, and the vector force is equal to the vector change of momentum. That is always true, and it is exactly true. (Some equations in physics represent approximations; this one is exact). > it says nothing about "frozen energy". No, that is a philosophical interpretation. > What you infer from it is of your own making and not of mine. That's correct. > Frozen energy indeed. Given that energy can be turned into mass and the process reversed with 100% recovery, it seems a reasonable interpretation. At any rate, it is certainly true that mass can be made to entirely disappear, leaving only mc^2 amount of energy behind. Put whatever name you want to that. > > in the amount mc^2, all of which can be recovered in matter- > > antimatter interactions. > > > We are not talking about energy recovery are we? Why yes, we are. We can take energy and turn it into mass. All the energy is gone, and what is on our plate is E/c^2 amount of mass. And we can take that mass and turn it back into energy, after which all the mass is gone and what is on our plate is mc^2 amount of energy. The relation E = mc^2 tells me how to relate these two different states which can be reversibly changed from one to another. I am indeed talking about energy "recovery", or rather energy equivalence, meaning that E can be turned into m, and m into E, and E = mc^2 tells you how much of each you get. > > So in a very real sense, matter IS > > energy. You are arguing some fundamental difference between > > "is" and "is equivalent to". I don't think it's an important > > distinction. > > > > > Yet you think the fundamental difference between force and momentum > always holds regardless of the level of notation. Because there is no equation that equates force and momentum in the same way. Force is not equated to an amount of momentum, but instead to its rapidity of change. You can get the same force from a tiny momentum changing rapidly, or a very large momentum changing slowly. What does "level of notation" mean? You really can't see the difference can you? In the case of matter-energy, we have E = constant*m, or m = constant*E. In the case of force-momentum, we do not. Simple as that. > You are willing to > infer that _in a very real sense_ matter is energy, Yep, because the relationship just has a proportionality constant. > but you refuse to > accept that same sense when it is applied to force and momentum. Yep, because the relationship does not just have a proportionality constant. > Is > that hyprocrisy or fickleness? Neither. It's making a distinction you seem unable to, between p and rate of change of p. Those are two different things. A large p can have a small dp/dt (or indeed, zero). A small p (indeed a zero p) can have a large dp/dt. They can be varied independently. They aren't the same thing. Of these two very different quantities, p and dp/dp, the one that force is related to is dp/dt. When F is large, dp/dt is large. When dp/dt is small, F is small. Yet for a given F, p can be anything at all, and for a given p, F can be anything at all. That makes F not proportional to p. - Randy
From: TomGee on 27 Sep 2005 03:21 Randy Poe wrote: > TomGee wrote: > > Randy Poe wrote: > > > It is a model telling you how the two things called force > > > and momentum are related. The equation doesn't cause this > > > relationship, but it is a relationship which is true. > > > > > > > > Still, it does not tell you what you imagined it did. > > It doesn't? Not having your telepathic powers, I don't know what > you mean. What did I imagine it told me and why doesn't it tell > me that? > > Anticipating your questions, I already answered them in my previous post. > > > > Equation, model, > > math construct, whatever, it simply states what a force is equal to in > > this particular case. All else you imagine it tells you is just that - > > imaginary. It does not imply that in the sense it is a necessary > > condition for the equation to hold. You can infer what you will from > > what it says, but at best an inference is still just a guess. > > Something I deduce mathematically from the equation F = dp/dt, > something that can be derived in clear, unambiguous, deductive > steps, is not what we normally term a "guess". > > Tell you what. Why don't you ask me a question you think I can't > answer from F = dp/dt? > > No, thanks. > > > > > Mass can be viewed as frozen energy, > > > > > Not according to the formula; > > No. The mathematical formulas in physics are not the physics, > they are merely one component of it. The physics postulates > are what gives meaning to the symbols in those equations. > > And don't the common usage of terms which are distinct at certain levels of research but can be used as equivalent terms at other levels of notation. > > > For instance, in F = dp/dt, the principle which we have used > since Newton's time is that, without exception, a time-changing > momentum can only arise as a result of a force, and the vector > force is equal to the vector change of momentum. That is always > true, and it is exactly true. (Some equations in physics represent > approximations; this one is exact). > > Newton formed the equation F=ma which is consistent with Galileo's work and in contrast to Aristotle's F=mv . He invented calculus where he obtained derivatives of functions one which is the equation you use above. Derivatives relate to velocity and speed in obtaining average velocity. Thuss, your use of derivatives is not relevant to our discussion. If you knew what a derivative is you would have known how preposterous your argument really is. > > > > it says nothing about "frozen energy". > > No, that is a philosophical interpretation. > > > What you infer from it is of your own making and not of mine. > > That's correct. > > > Frozen energy indeed. > > Given that energy can be turned into mass and the process > reversed with 100% recovery, it seems a reasonable interpretation. > > Oh, I don't think it is unreasonable, I am just surprised that you are willing to accept such an extrapolation when it is convenient for you to do it but yet you argue that I cannot do the same. > > > At any rate, it is certainly true that mass can be made to > entirely disappear, leaving only mc^2 amount of energy > behind. Put whatever name you want to that. > > > > in the amount mc^2, all of which can be recovered in matter- > > > antimatter interactions. > > > > > We are not talking about energy recovery are we? > > Why yes, we are. We can take energy and turn it into mass. All > the energy is gone, and what is on our plate is E/c^2 amount of > mass. And we can take that mass and turn it back into energy, > after which all the mass is gone and what is on our plate is > mc^2 amount of energy. The relation E = mc^2 tells me how to relate > these two different states which can be reversibly changed from > one to another. I am indeed talking about energy "recovery", or > rather energy equivalence, meaning that E can be turned into > m, and m into E, and E = mc^2 tells you how much of each you get. > > I was hoping you would answer no, but you insist in misunderstanding the equation. I guess that's why you inserted the dp/dt equation where it does not belong. You don't understand math all that well and so you fake your way through discussions. I'm the same way but I don't try to fake my way through it. Math is not the road to reality so I am better off not knowing so much about it that it limits my view of reality like it does yours. > > > > > So in a very real sense, matter IS > > > energy. You are arguing some fundamental difference between > > > "is" and "is equivalent to". I don't think it's an important > > > distinction. > > > > > > > > Yet you think the fundamental difference between force and momentum > > always holds regardless of the level of notation. > > Because there is no equation that equates force and momentum > in the same way. Force is not equated to an amount of momentum, > but instead to its rapidity of change. > > Rate of change, true, but in physics, force is also a physical influence that tends to change the position of an object with mass such that F=mv, and momentum is equal to the product of the mass and its velocity. How much more equivalence than that do you demand? > > > You can get the same > force from a tiny momentum changing rapidly, or a very large > momentum changing slowly. > > What does "level of notation" mean? > > Notation is a set of written symbols used to represent something. Your equation is one level of notation and your inferences from it are a different level of notation about the same subject. > > > You really can't see the difference can you? In the case of > matter-energy, we have E = constant*m, or m = constant*E. > In the case of force-momentum, we do not. Simple as that. > > > You are willing to > > infer that _in a very real sense_ matter is energy, > > Yep, because the relationship just has a proportionality constant. > > > but you refuse to > > accept that same sense when it is applied to force and momentum. > > Yep, because the relationship does not just have a proportionality > constant. > > So you say energy must have a constant times mass and mass must have a constant times energy (don't you mean as a divisor?), in order for the two to be equivalent? I thought you said nothing having different units can ever be equivalent! But since the formula E=mc^2 does not say mass and energy are equivalent, you are simply inferring that at a different level of notation than the level of notation of the formula, huh? Once again, it's okay for you the goose to do it but not okay for me the gander to do it, eh? > > > > Is > > that hyprocrisy or fickleness? > > Neither. It's making a distinction you seem unable to, between p > and rate of change of p. > > I will guess it's a combo of both because you are unable to understand that the topic is p and not a derivative of p. > > SNIP more irrelevant dp/dt nonsense.
From: Randy Poe on 27 Sep 2005 09:51 TomGee wrote: > Randy Poe wrote: > > TomGee wrote: > > > Randy Poe wrote: > > > > It is a model telling you how the two things called force > > > > and momentum are related. The equation doesn't cause this > > > > relationship, but it is a relationship which is true. > > > > > > > > > > > Still, it does not tell you what you imagined it did. > > > > It doesn't? Not having your telepathic powers, I don't know what > > you mean. What did I imagine it told me and why doesn't it tell > > me that? > > > > > Anticipating your questions, I already answered them in my previous > post. > > Well since I don't recall seeing anything like that, I guess it will have to remain an eternal mystery. Such is life. > > > Equation, model, > > > math construct, whatever, it simply states what a force is equal to in > > > this particular case. All else you imagine it tells you is just that - > > > imaginary. It does not imply that in the sense it is a necessary > > > condition for the equation to hold. You can infer what you will from > > > what it says, but at best an inference is still just a guess. > > > > Something I deduce mathematically from the equation F = dp/dt, > > something that can be derived in clear, unambiguous, deductive > > steps, is not what we normally term a "guess". > > > > Tell you what. Why don't you ask me a question you think I can't > > answer from F = dp/dt? > > > > > No, thanks. OK, then you agree that this equation suffices to tell me all I want to know about how forces affect momentum. > > > > Mass can be viewed as frozen energy, > > > > > > > Not according to the formula; > > > > No. The mathematical formulas in physics are not the physics, > > they are merely one component of it. The physics postulates > > are what gives meaning to the symbols in those equations. > > > And don't the common usage of terms which are distinct at certain > levels of research but can be used as equivalent terms at other levels > of notation. What are "levels of notation"? That sentence seems to be missing something. It starts out as if it was going to ask a question, but I can't fathom what the question was going to be. > > For instance, in F = dp/dt, the principle which we have used > > since Newton's time is that, without exception, a time-changing > > momentum can only arise as a result of a force, and the vector > > force is equal to the vector change of momentum. That is always > > true, and it is exactly true. (Some equations in physics represent > > approximations; this one is exact). > > > Newton formed the equation F=ma No, he did not. F = ma is a special case of F = dp/dt when mass is constant and p = mv. The time derivative of mv is ma when mass is constant. "Lex II: Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur." "The CHANGE IN MOTION is proportional to the impressed force, and is made along the straight line along which it is impressed." As I said earlier in the thread, Newton makes it clear in the discussion which follows that "motus" is the product of mass and velocity, i.e. what we now call momentum. So Newton here is saying that vector force is proportional to vector change in momentum. > which is consistent with Galileo's work > and in contrast to Aristotle's F=mv . He invented calculus where he > obtained derivatives of functions one which is the equation you use > above. Derivatives relate to velocity and speed in obtaining average > velocity. I see. That's the only place derivatives are ever used. You are incorrect. > Thus, your use of derivatives is not relevant to our > discussion. If TomGee's Law was true that derivatives are only used for speeds and there's no such thing as the derivative of a momentum, then perhaps you'd be right that F = dp/dt is not relevant to the relation between force and momentum. However, TomGee's Law is ridiculously, laughably incorrect. > If you knew what a derivative is you would have known how > preposterous your argument really is. Oh? Please, ridicule me. Tell me how preposterous my argument really is, based on what a derivative "really is". > > > Is > > > that hyprocrisy or fickleness? > > > > Neither. It's making a distinction you seem unable to, between p > > and rate of change of p. > > > > > I will guess it's a combo of both because you are unable to understand > that the topic is p and not a derivative of p. The QUESTION is whether F = p, and the answer is that F = dp/dt. I am glad that at last you recognize that p and dp/dt are not the same. Therefore it can not be simultaneously true that force is dp/dt and is p. > SNIP more irrelevant dp/dt nonsense. Yes, you're fond of the "irrelevant" word aren't you? "Irrelevant" seems to mean "Oops, he just answered a question that I thought was impossible and turns out to be trivial. Better abandon that line of argument." - Randy
From: TomGee on 27 Sep 2005 16:00 PD wrote: > TomGee wrote: > > PD wrote: > > > > > > And how is YOUR model falsifiable, TomGee? What is good for the goose > > > is good for the panderer. > > > > > > > > Just find a way to show that time is not a property of matter, or that > > time does not pass inversely proportional to an object's state of > > motion, or that space and time are interdependent, or that the s-t > > continuum actually exists somewhere readily accessible for anyone > > wishing to go there, and on and on and on. > > You are under a mistaken impression of what "falsifiability" of a > theory means. This term, as it is used by scientists, means the ability > to confront a prediction of a theory against experimental observation. > If a theory makes no unique prediction that can be confronted with > experiment, then it is not falsifiable. A theory that is not > falsifiable is useless as a theory. > > Okay, but your theory that time is not a property of matter - that you can falsify, right? And SR's theory of time dilation - that you can falsify against experimental observation, right? And AE's theory that space and time are interdependent - that you can falsify against the evidence that time may be dependent on space because matter is dependent upon space but space is not dependent on time or matter and thus AE's interdependence theory of space and time is falsified! Your theory that time is not a property of matter has no support for it and thus it's only opinion, while mine is extrapolated from SR's Twin Paradox and at least one other time dilation effect experimental observations. Two against zero = you lose. Einstein's theory of time and space interdependence is valid only in his imaginary s-t continuum and not in our universe where that interdependence is non-existent, yet you believe it to be true in all cases even though that is obviously false. What good is falsifiability if you only apply it to me and not to those in whom you place absolute faith? Was his static universe theory falsifiable? Was his theory that motion is meaningful only between two bodies falsifiable? Yes, and he contradicted himself when he also said that time and space are dependent upon the motion of an observer, since that makes an observer's motion also meaningful. > > > I somehow got the idea that you knew what you were talking about when > you used that term to question the falsifiability of Louis's ether. I > see that I was mistaken. > > Yes, you were mistaken in not seeing the dripping sarcasm of my charge. We are dealing only with effects for which we offer explanations of Dark Matter and Energy. We are already at odds as to whether it's matter or energy, or both. We must be ready to change our particular views as new evidence shows up, but there is nothing wrong with offering up our ideas about what is the cause behind the observed effects. In fact, it's a good thing to do that because it seems every important serendipitous event comes from the birth of a new idea. Closing your mind to new ideas, then, is not good, PD. Read My Lips: NOT GOOD!!
From: platopes on 27 Sep 2005 16:06
PD wrote: > TomGee wrote: > > PD wrote: > > > > > > And how is YOUR model falsifiable, TomGee? What is good for the goose > > > is good for the panderer. > > > > > > > > Just find a way to show that time is not a property of matter, or that > > time does not pass inversely proportional to an object's state of > > motion, or that space and time are interdependent, or that the s-t > > continuum actually exists somewhere readily accessible for anyone > > wishing to go there, and on and on and on. > > You are under a mistaken impression of what "falsifiability" of a > theory means. This term, as it is used by scientists, means the ability > to confront a prediction of a theory against experimental observation. > If a theory makes no unique prediction that can be confronted with > experiment, then it is not falsifiable. A theory that is not > falsifiable is useless as a theory. > > I somehow got the idea that you knew what you were talking about when > you used that term to question the falsifiability of Louis's ether. I > see that I was mistaken. > If motion were a series of effects, each requiring its own cause, would a heavier object gravitate more slowly toward a large mass than a lighter object? That is, would more of this constant force be needed to move a heavier object than a lighter one? p |