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From: TomGee on 2 Oct 2005 05:08 Randy Poe wrote: > TomGee wrote: > > No, sorry, Randy. Your eyes must be crossed. Tipler in my quote does > > not equate the work done _to_ KE at all. > > I'm reading this message: > http://groups.google.com/group/sci.math/msg/dd6f6945e97b7e6c > > in which you provided the following quote from Tipler: > > "The work done by an unbalanced force...on...[an object]...equals the > change in the kinetic energy of the...[object]" > > > He specifically refers to the > > work done on an object, > > yes, and says that it equals the change in KE of the object. > > But you misunderstood the word "on" to mean "to", which is why I asked the question below. > > > no on KE. How would you do work on KE, > > anyways, since KE is the energy a body has due to its motion? > > How do you confuse sentences so thoroughly? > > The work is done by the force on the object. Work is energy. > It is translated into kinetic energy of the object. Nowhere > did I say, or Tipler say, that "work is done on the KE". > > No, but you said that work was done _to_ KE. > > > However the quote you gave clearly says the work is EQUAL TO > (not "done on") the change in KE, and I agree. > > How, on second reading of your own quote, did this get transmuted > to "the force is equal to the KE"? Do you see the word "force" > in that passage? > > You should be asking yourself how you took the word "on" to mean "to", because that seems to be your major problem with reading, which is why I said your eyes musta got crossed. If you have such a handicap, your poor reading comprehension level is of course understandable, but if not, you're making a laughingstock of yourself here on these ngs. I would say that you're the one who should not be talking physics having such poor reading skills.
From: Randy Poe on 2 Oct 2005 18:08 TomGee wrote: > Randy Poe wrote: > > TomGee wrote: > > > Randy Poe wrote: > > > > Because dp/dt is not equal to p. > > > > > > > > > > > Hey, that's my position, not yours! A derivative cannot be equal to > > > the function from which it is derived! > > > > If that's your position, then can you explain this comment of > > yours? > > > > "False logic. dp/dt is a derivative of p so if force is a derivative > > of > > p, it must by definition also be p." > > > > http://groups.google.com/group/alt.sci.physics/msg/c61fe7149a24099a > > > > It sure looks to me like you're saying the derivative of p > > is also "by definition" p. > > > > > Yes, it is, but it is not equal to p. So the derivative of p is the same thing as p, but it's not equal to p. You're going to have to explain that one to me. In my universe, if two things are the same by definition, they're equal. > We can measure momentum as p=mv > without knowing it's rate of change, then we can derive F=dp/dt from > it, but we cannot derive it unless we know the mass and velocity first. Um, incorrect. > They cannot be equal to the same thing but they can be the same thing > because one is a quantity and the other is the force of that quantity. That makes no sense. Again, if two things are the same thing, they're equal. > > By the Tipler quote that says force is the time rate of change > > of momentum? > > > > Again, how does that prove that F = dp/dt is wrong? > > > > > Another one of your bad inferences. Tipler said that force is the time rate of change of momentum. That's not an "inference", it's in the quote you provided. Above, you claim the Tipler quote proves me wrong. How does the Tipler quote prove me wrong? What is he saying that is different from what I'm saying? > I could just as easily infer that > you said p=mv is wrong. Well, I did, actually. It's true in non-relativistic situations, but not in general. > > Yes, I really can't see how "force is the time rate of change > > of momentum" proves F = dp/dt is wrong. > > > > > Never said that. Another one of your false inferences. No, Tipler said it. And you said the Tipler quote proved F = dp/dt is wrong. > > Nor can I see how "work done on an object equals change in > > KE of the object" contradicts "force and momentum are not > > interchangeable". > > > Aren't you the one who said KE is not changed by an external force? No, I never said such a thing. Can you provide the quote where you garbled that inference from? - Randy
From: TomGee on 3 Oct 2005 02:24 Randy Poe wrote: > TomGee wrote: > > Randy Poe wrote: > > > TomGee wrote: > > > > Randy Poe wrote: > > > > > Because dp/dt is not equal to p. > > > > > > > > > > > > > > Hey, that's my position, not yours! A derivative cannot be equal to > > > > the function from which it is derived! > > > > > > If that's your position, then can you explain this comment of > > > yours? > > > > > > "False logic. dp/dt is a derivative of p so if force is a derivative > > > of > > > p, it must by definition also be p." > > > > > > http://groups.google.com/group/alt.sci.physics/msg/c61fe7149a24099a > > > > > > It sure looks to me like you're saying the derivative of p > > > is also "by definition" p. > > > > > > > > Yes, it is, but it is not equal to p. > > So the derivative of p is the same thing as p, but it's not > equal to p. You're going to have to explain that one to me. > > I do below. I don't expect you to agree. > > > In my universe, if two things are the same by definition, > they're equal. > > Yes, but in the real universe, they're not always equal. What objects or quantities or properties are equal to depends on more than just an equal sign. If you say, "These two mountains are equal", the statement is nonsense. For it to make sense, you must qualify it something to compare the two, height, area, mineral amounts, difficulty in climbing, etc. Since that is not necessary in your universe, there is no way for you to agree. > > > We can measure momentum as p=mv > > without knowing it's rate of change, then we can derive F=dp/dt from > > it, but we cannot derive it unless we know the mass and velocity first. > > Um, incorrect. > > > They cannot be equal to the same thing but they can be the same thing > > because one is a quantity and the other is the force of that quantity. > > That makes no sense. Again, if two things are the same thing, > they're equal. > > Yes, in your universe. > > > > > By the Tipler quote that says force is the time rate of change > > > of momentum? > > > > > > Again, how does that prove that F = dp/dt is wrong? > > > > > > > > Another one of your bad inferences. > > Tipler said that force is the time rate of change of momentum. > That's not an "inference", it's in the quote you provided. > > Above, you claim the Tipler quote proves me wrong. > > In your universe, proving you wrong equals proving F=dp/dt wrong, so that's why you inferred I said that. > > > How does the Tipler quote prove me wrong? What is he saying > that is different from what I'm saying? > > > I could just as easily infer that > > you said p=mv is wrong. > > Well, I did, actually. It's true in non-relativistic situations, > but not in general. > > But in your universe relativistic situations are reality while in our real universe, relativistic situations are imaginary. Not only are your eyes crossed, but your brain is upside down. > > > > > Yes, I really can't see how "force is the time rate of change > > > of momentum" proves F = dp/dt is wrong. > > > > > > > > Never said that. Another one of your false inferences. > > No, Tipler said it. And you said the Tipler quote proved > F = dp/dt is wrong. > > > > Nor can I see how "work done on an object equals change in > > > KE of the object" contradicts "force and momentum are not > > > interchangeable". > > > > > Aren't you the one who said KE is not changed by an external force? > > No, I never said such a thing. Can you provide the quote where > you garbled that inference from? > > - Randy
From: TomGee on 3 Oct 2005 02:37 Randy Poe wrote: > TomGee wrote: > > No, sorry, Randy. Your eyes must be crossed. Tipler in my quote does > > not equate the work done _to_ KE at all. > > "The work done by an unbalanced force...on...[an object]...equals the > change in the kinetic energy of the...[object]" > > Subject of sentence: work done on an object. > Object of sentence: change in KE of object > Verb: equals. > > You really don't think the passage above says the work done > equals the change in KE? You don't see this sentence equating > work and KE? You don't see "work" at the start, "KE" at the > end, and "equals" in the middle? > > - Randy > > I don't see the word "on" meaning "to" in any way.
From: Randy Poe on 3 Oct 2005 10:59
TomGee wrote: > Randy Poe wrote: > > TomGee wrote: > > > No, sorry, Randy. Your eyes must be crossed. Tipler in my quote does > > > not equate the work done _to_ KE at all. > > > > "The work done by an unbalanced force...on...[an object]...equals the > > change in the kinetic energy of the...[object]" > > > > Subject of sentence: work done on an object. > > Object of sentence: change in KE of object > > Verb: equals. > > > > You really don't think the passage above says the work done > > equals the change in KE? You don't see this sentence equating > > work and KE? You don't see "work" at the start, "KE" at the > > end, and "equals" in the middle? > > > > > I don't see the word "on" meaning "to" in any way. The relevant verb is "equals". When Tipler says the work EQUALS the change in KE, you don't read this as the work is EQUAL TO the change in KE? Remember (I know your memory is short, but your words are quoted above), you are saying Tipler does not equate work done, to change in KE. In my universe, if I say x = y, I am equating x to y. - Randy |