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From: Randy Poe on 29 Sep 2005 08:52 TomGee wrote: > Randy Poe wrote: > > TomGee wrote: > > Yes, I keep talking about the relation between force and > > momentum, whereas you keep correcting me that the topic > > of discussion is the relation between force and momentum, > > clearly a different thing. Sorry about that. > > > No, you keep talking about a derivative of momentum Because dp/dt = F is a derivative of momentum. > in a futile effort > to show that momentum is not a force. Because dp/dt is not equal to p. > And you can't grasp what's wrong with that picture. Because your ignorance is impervious. > > And you've said "every physics textbook" does so, all over > > the place. > > > Is that a fact or is that your opinion based on one of your far-out > inferences? Cite the post so that I can check is you're lying or not. The exact quote was this: >> Sure "we" do, just read a physics book. It is rare where we don't >> use terms like force and momentum nterchangably. So I read this as saying that you believe if I pick up any physics textbook, I will find that force and momentum are used interchangeably. It is rare that they do not. Therefore it should be easy to find such a passage in any physics book. > > You can no doubt provide a quote from a physics > > textbook where the term momentum is used to mean a force, > > right? Thereby proving me wrong when I insist that nowhere > > in physics is momentum used to mean "force"? > > > How would that show that "nowhere in physics" is it used that way? Read it again. "Nowhere in physics" is MY position. Your position is that it's rare for momentum and force NOT to be used equivalently. Keep your position straight. Finding such a passage in a physics textbook would prove me wrong, because my claim is that such a passage doesn't exist. Yours (do try to remember this) is that it does, and such passages are common. [Snip remaining rant. Same old story: Tom thinks p and dp/dt are interchangeable]. - Randy
From: Randy Poe on 29 Sep 2005 08:54 TomGee wrote: > > And you've said "every physics textbook" does so, all over > > the place. > > > Is that a fact or is that your opinion based on one of your far-out > inferences? Cite the post so that I can check is you're lying or not. The post in question was this one. http://groups.google.com/group/sci.physics/msg/d5b178f4c27d1e4f I'll state up front that my memory of the exact words was inaccurate, but I believe I accurately reflect the content. - Randy
From: TomGee on 29 Sep 2005 15:38 Heh heh. Read again what Tipler says: "...the net force equals the change in kinetic energy...." You deny momentum is kinetic energy, so how can he be talking about us equating that to momentum unless he believes both are the same thing?
From: Randy Poe on 29 Sep 2005 16:04 TomGee wrote: > Heh heh. Read again what Tipler says: > "...the net force equals the change in kinetic energy...." Really? Then why did you write this when you quoted Tipler before: "The work done by an unbalanced force...on...[an object]...equals the change in the kinetic energy..." What is the object of that sentence? Is it "net force"? > You deny momentum is kinetic energy, I do. > so how can he be talking about us equating > that to momentum "Momentum", like "net force", is not something that was equated to "kinetic energy" in your actual quote. The quote you provided equated work done to KE, and I agree that when a force does work on an object, the work done is equal to the KE increase of the object. - Randy
From: TomGee on 29 Sep 2005 16:58
No, sorry, Randy. Your eyes must be crossed. Tipler in my quote does not equate the work done _to_ KE at all. He specifically refers to the work done on an object, no on KE. How would you do work on KE, anyways, since KE is the energy a body has due to its motion? |