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From: TomGee on 23 Sep 2005 18:34 Randy Poe wrote: > TomGee wrote: > > Herman Trivilino wrote: > > > "TomGee" <lvlus(a)hotmail.com> wrote ... > > > > > > >> > If you think you did not say it. then just what do you mean by F=dp/dt? > > > >> > > > >> Wow! Don't you know the difference between a quantity and its time rate > > > >> of > > > >> change? > > > >> > > > >> We can write v=dx/dt, where v is velocity and x is position. Do you > > > >> think > > > >> this means that velocity and position are equal? And that we can write > > > >> v=x?! > > > >> > > > > So you don't know what he means by that either, eh? > > > > > > Yes, I do. He's talking about a derivative, or rate of change. In this > > > case, its a rate of change with respect to time. > > > > > > > > Yes I know that, but what is the relevance of that to the topic? > > > > > > > > > p is the momentum. > > > > > > > > Yes I know that, but what is the relevance of that to the topic? > > > > > > > > > dp/dt is the rate at which p changes with time. > > > > > > > > Yes I know that, but what is the relevance of that to the topic? > > > > > > > > > F is the net force. > > > > > > > > Yes I know that, but what is the relevance of that to the topic? > > > > > > > > > He's claiming that F=dp/dt, a valid claim. > > > > > > > > 2+2=4 is a valid claim too, but (You guessed it!): Yes I know that, > > but what is the relevance of that to the topic? > > Let me refresh your obviously-failing memory as to the topic: > > I said this: > > > > That doesn't tell use "energy can be used as a force". It > > > > does relate force and momentum: F = dp/dt. > > You responded: > > > > It would be a pity if you were right, but you contradict yourself > > > immediately by saying above that force and momentum are equivalent. > > So the topic is "Tom just informed me I said force and momentum > are equivalent". > > I asked: > > Where did I say that? I would have snipped more, but I wanted > > to leave all the stuff you quoted from me so you can point > > me to the passage where you think I said F = p. > > And you responded: > > > If you think you did not say it. then just what do you mean by F=dp/dt? > > So the topic is still "Tom informed me I said force and momentum > are equivalent", and you amplified it to say that "F = dp/dt > is a statement that force and momentum are equivalent". > > I did not amplify it. You're the one who said it "relates" force and momentum. I simply asked you to explain how you think it relates to them. > > > The next few posts, including this one, explain the statement > "F = dp/dt" does not say "force and momentum are equivalent". > > I did not ask you for that. And you have not yet answered my question of what you meant by the statement. > > > Since I asked you to tell me where I said F = p (see immediately > above) and you said "if you think you did not say it, then just > what do you mean by F=dp/dt"? We all interpret you to be saying > that saying F=dp/dt is equivalent to F=p. > > Well, you all are wrong, obviously, in your assumptions. What part do you not understand about, "what do you mean by F = dp/dt?" Plain English and simple question, what's so difficult to understand about it? > > > > > You're claiming that F=p, an invalid claim. > > > > > No, I'm claiming no such thing. > > Well, OK. You're claiming that *I* said F=p. And you're claiming > that when I said F=dp/dt, that was a statement that F=p. > > No, I'm not. That's your understanding of what I said, but your understanding is wrong. > > > So since the topic is "what does F=dp/dt mean", the discussion > of the meaning of "dp/dt" is relevant. > > Why, if you cannot decipher the very very very simple question? Why bother with discussion if you jump to wrong conclusions about a simple question and infer some dark evil trap I am setting for you? No need for me to do that; you do that to yourself without any help from me. I want discussion. It delights me no end. But if you're not listening, why do you bother? Just to make noise? Or to show off how much you know? That's readily obvious to all who read your posts.
From: TomGee on 23 Sep 2005 18:39 Herman, you answered something but you did not answer my question. It was a plain and simple question yet neither you nor your buddy understood it. So I must say, it doesn't get any less relevant than that.
From: TomGee on 23 Sep 2005 18:49 Well, thanks for your input, Paul. Would you be able to answer my question to Randy? Herman tried but he had no luck with it either. Or maybe you can clarify the question for them as you have clarlfied the equation which Randy claims "relates" to our topic.
From: stephen on 24 Sep 2005 16:23 In sci.math Randy Poe <poespam-trap(a)yahoo.com> wrote: > TomGee wrote: >> Okay, Randy, but this first: >> Work is a purposeful physical effort directed toward doing something. >> It is a means for energy transfer. >> Entropy is a measure of the energy in a system or process that is >> unavailable to do work. >> Perpetual Motion is a long-held concept of a system that could operate >> indefinitely, once started, without any further expenditure of outside >> energy. Such a system is not in accord with the fundamental laws of >> physics. Any system will run down when left to itself, through various >> forms of attrition. On the subatomic level, perpetual motion may be >> said to be observed in the motion of electrons around a nucleus. Even >> here, however, the concept of entropy (the second law of >> thermodynamics) views the universe as a whole as incapable of perpetual >> motion. >> Microsoft Encarta Reference Library 2005. 1993-2004 Microsoft >> Corporation. All rights reserved. > Wow. > More later. But just one comment on this: You need a better > reference source. Everything you have posted from Encarta on this > topic has been wrong. Not just subtly wrong, but wrong in > huge ways, wrong on basic elementary stuff, wrong according > to any introductory high-school level physics book. > That Microsoft would put this trash out under their name is > appalling, but not surprising. You also might want to check the Encarta entry first hand, if you can. It does not seem to be available online without a subscription, but I know from first hand experience that TomGee changes words and phrases when he "quotes" the Encarta. Stephen
From: stephen on 24 Sep 2005 16:44
In sci.math Randy Poe <poespam-trap(a)yahoo.com> wrote: > TomGee wrote: >> Herman Trivilino wrote: >> > "TomGee" <lvlus(a)hotmail.com> wrote ... >> > >> > >> Where did I say that? I would have snipped more, but I wanted >> > >> to leave all the stuff you quoted from me so you can point >> > >> me to the passage where you think I said F = p. >> > >> >> > > If you think you did not say it. then just what do you mean by F=dp/dt? >> > >> > Wow! Don't you know the difference between a quantity and its time rate of >> > change? >> > >> > We can write v=dx/dt, where v is velocity and x is position. Do you think >> > this means that velocity and position are equal? And that we can write >> > v=x?! >> > >> So you don't know what he means by that either, eh? > He just told you what I meant. I didn't say F = p, I said F is the > time rate of change of p. Even TomGee's Oracle agrees with you. From the Allmight Encarta According to Newton's second law of motion, named after the English astronomer, mathematician, and physicist Sir Isaac Newton, the force acting on a body in motion must be equal to its time rate of change of momentum. Another way of stating Newton's second law is that the impulse, that is, the product of the force multiplied by the time over which it acts on a body, equals the change of momentum of the body. This is the last paragraph of http://encarta.msn.com/encyclopedia_761554136/Momentum.html The article seems to be written for a totally untechnical audience. It does not include any equations, so it is likely TomGee will be unable to understand dp/dt. Stephen |