Maybe we can pause right there. All along I have talked only about gravity. Weight is not gravity, weight is the result of a mass accelerated (pulled even if unmoving) by gravity and other forces (centripetal being one) at the Earth's (Moons, etc. ...) surface. That is also roughly the Apparent Gravity discussion on the Wikipedia gravity page.
All along I have only held that those extra force components of Apparent Gravity are not Gravity, just a composite/resultant force that is very close to the actual force of gravity. That is why I keep saying as far as gravity goes I don't care about the centripetal accelerations.
Well I'm glad that we are finally getting there, but I did offer this explanation of the disagreement back in #116, and you rejected it outright. Although there are no extra forces involved. I wish you would stop saying that. Never mind. See below.
Quote:
Originally Posted by Hiro
And that directly extends to weight, which rolls back around to where this all started -- the mess over pounds as mass, pounds as weight (and my snide eventual comment about pounds as currency) and the various early posters seemingly willing to ignore they were dealing with an overloaded term.
I won't disagree that other posters became muddled on this - that is why I joined the discussion - and I liked your currency comment.
Quote:
Originally Posted by Hiro
The remainder of your post looks mostly OK, up until you call your g the gravity we use on Earth. Your g is not gravity, it is a version of apparent gravity (the interaction between gravity and ideal spherical centripetal acceleration).
It is those little slips in technical terminology precision that end up perpetuating the issue.
Thanks, but I disagree on two counts:
Mostly OK? Meaning not completely? Don't make that statement without backing it up with specific criticism.
There is no imprecision in that use of g; even though it has been used both to describe the earth's standard gravity (which itself is an average that takes into account rotation) and the local variable value, I defined my use of it as the latter at the outset, so neither imprecise nor ambiguous. I have never seen it used to describe local field strength, which appears to be your preferred definition, but perhaps you can provide a citation for that use.
Quote:
Originally Posted by Hiro
That's D'Alambert's Principle. It just makes the math easier, and unfortunately easier to safely miss-mash the math together. Convenient for a problem at a time, but the mis-mash methods are not necessarily good for generality. Better to save the vector combinations for as late in the evaluation as humanly possible.
No, it's not. It's Einstein's equivalence principle. D'Alembert's Principle (not D'Alambert's) is just a restatement of dynamic equilibrium in a constrained system, and does not mention the equivalence of acceleration and gravity. I've never had to resort to using it.
Quote:
Originally Posted by Hiro
As for whether or not the gravity and the acceleration-at-a-point are are indistinguishable, that is a 'it depends' statement. To an observer standing on the ground with human senses, yes indistinguishable; to a gravitometer calibrated for lat/long and GPS altitude, no quite distinguishable*. Also they are very distinguishable when you are trying to do physical simulations. If you combine the equations algebraically as you have done the math gets ever more nasty when also doing body-body interactions. When you keep the components separated, use sensible local origins and use geometric methods the math is much simpler (though there are more discrete operations), it's also easier to program and extend for more generality (especially important when you don't know what the next question for the sim will be). Seeing as I'm very involved in the latter issues, the side of 'it depends' I fall on defaults to separate components rather than combined far less flexible solutions (try to dynamically simulate something as simple as long range rocket assisted sensor platform delivery using your combined apparent gravity equation compared to by-component methods).
No, there is no "it depends" about it. That particular equivalence principle is completely universal and has no caveats other than the one I quoted (infinitesimally small observer). I have no idea where you got that from, or what you mean by "they are very distinguishable when you are trying to do physical simulations", or where you are going at all with the rest of that comment for that matter, but I would be curious to know. Either you misunderstood my statement of the principle, your simulations are badly flawed, or I am completely missing your point.
Quote:
Originally Posted by Hiro
We should be, it's just a case of say what we mean, mean what we say. Not something almost and incredibly close to like we mean or say. It's just about maintaining discipline when using terminology and I see great benefit with precise use of terminology.
Here I agree entirely, but would point out that I was very careful to define all terms from the outset, made no assumptions or approximations, and dealt only in idealized physics. If you are going to demand precision, you might want to review your own posts. If our original disagreement is just field strength versus local acceleration / weight, then I think that we have resolved that, leaving just the other details that I addressed above.
It has been interesting reading both of your arguments. I think you've actually been arguing over the definition of the word weight. One wants it to refer to the force of attraction between two bodies based on mass. The other wants it to refer to the reading on a scale set on the surface of the earth.
It has been interesting reading both of your arguments. I think you've actually been arguing over the definition of the word weight. One wants it to refer to the force of attraction between two bodies based on mass. The other wants it to refer to the reading on a scale set on the surface of the earth.
Well maybe, but more by implication, since Hiro never explicitly disputed it. However, weight is defined as mg and obviously m is invariant with location. So if g does not include all location-dependent factors the factors that affect weight, then either the definition of weight is incorrect, or it is not what we measure on a scale. I doubt anyone would argue the latter, but I've learned not to be surprised at anything I read here.
It is clear to me that Hiro wants g to be used purely to mean the gravitational field strength of the earth - in which case he is correct - it is position dependent only due to the oblateness of the earth, and independent of rotation. But while that is a perfectly valid quantity, the whole argument arose because the precise definition of weight requires a different value for g - the one that I derived that does take into account rotation. That this is correct is trivially obvious; in addition to the very simple but rigorous derivation that I gave, it is covered in countless basic physics texts and even the entry entitled "Gravity of Earth" on the ever-controversial Wikipedia. It is a little unfortunate that Wikipedia screws up the explanation by introducing a centrifugal force (which is nonetheless valid in the less elegant rotating frame of reference), but I think it is just trying to explain it in lay terms.
Anyway, I think the basic disagreement is pretty much resolved.
Well I'm glad that we are finally getting there, but I did offer this explanation of the disagreement back in #116, and you rejected it outright. Although there are no extra forces involved. I wish you would stop saying that. Never mind. See below.
As for 116 you are reading what you want to see, not what I said. I dismissed the majority of your post precisely because it was about the mathematical contributions of centripetal force. Not gravity. so no need for me to respond to it in detail at all.
Quote:
Originally Posted by muppetry
Mostly OK? Meaning not completely? Don't make that statement without backing it up with specific criticism.
[*]There is no imprecision in that use of g; even though it has been used both to describe the earth's standard gravity (which itself is an average that takes into account rotation) and the local variable value, I defined my use of it as the latter at the outset, so neither imprecise nor ambiguous. I have never seen it used to describe local field strength, which appears to be your preferred definition, but perhaps you can provide a citation for that use. [/LIST]
I did. Which you apparently don't like because I don't agree with the use of g and calling that gravity in your text. The web is also muddled on the topic so most links are irrelevant, I happen to agree with NIST. And I wasn't grading for partial credit so I'm more than willing to say OK on the math without having examined it to the point I would vouch for it. That's not a cut, that's more like I trust you didn't screw up the basics.
Quote:
Originally Posted by muppetry
No, it's not. It's Einstein's equivalence principle. D'Alembert's Principle (not D'Alambert's) is just a restatement of dynamic equilibrium in a constrained system, and does not mention the equivalence of acceleration and gravity. I've never had to resort to using it.
Well we can agree to disagree how to interpret your statements, because on my reading I do see those, I'm not going to argue that your view is wrong because it isn't, it's just at a different abstraction level that derives from the same first principles which is where D'Alembert comes in at a lower level that Einstein (name spelling error inconsequential unless you are trying to be a puffery about it).
Quote:
Originally Posted by muppetry
No, there is no "it depends" about it. That particular equivalence principle is completely universal and has no caveats other than the one I quoted (infinitesimally small observer). I have no idea where you got that from, or what you mean by "they are very distinguishable when you are trying to do physical simulations", or where you are going at all with the rest of that comment for that matter, but I would be curious to know. Either you misunderstood my statement of the principle, your simulations are badly flawed, or I am completely missing your point.
I think you are really missing the point. The sim is well regarded. Not worth arguing over implementation that works, it does and many folks hate the geometric formulations because it's not what is taught in Physics 101, but they make almost everything soooo much simpler.
Strange stuff in a language I don't understand, but that certainly isn't physics...
We seem to have regressed again, and are probably on the wrong side of the law of diminishing return. Many might say we were there days ago, but perseverance is a virtue isn't it?
Let's just agree to differ then. I'm still frustrated that you never addressed any of my arguments with anything resembling technical responses, even when goaded to do so, but still had the nerve to accuse me of lack of precision and technical understanding. Your prerogative though, to use whatever form of argument works best for you. One of the good and bad things about the internet forum is that, in the end, there is no way to prevail in the face of single-minded and determined opposition. I failed miserably to convince you that mathematics and physics trump all else, and, not surprisingly, you failed to convince me that we should regard the basic laws of physics as fuzzy and open to our individual interpretation. At least that's how I read it.
With your permission I'd like to declare this horse fully expired, or feel free to take a parting shot and do the honors yourself.
you failed to convince me that we should regard the basic laws of physics as fuzzy and open to our individual interpretation. At least that's how I read it.
Yes the horse is dead, but only because you have decided that if it isn't said exactly how you want to frame it it becomes "fuzzy and open to our individual interpretation" -- even when I cite the National Institute of Standards and Technology as the source of the interpretation I'm going by-- I guess that puts your last statement in total perspective...
I don't need the internet forums to validate my ego, I'll happily continue to let the research contracts/sponsorships be my validation. If I really was as fuzzy and making individual interpretations as you seem to think, the follow on money would have dried up long ago.
Yes the horse is dead, but only because you have decided that if it isn't said exactly how you want to frame it it becomes "fuzzy and open to our individual interpretation" -- even when I cite the National Institute of Standards and Technology as the source of the interpretation I'm going by-- I guess that puts your last statement in total perspective...
I don't need the internet forums to validate my ego, I'll happily continue to let the research contracts/sponsorships be my validation. If I really was as fuzzy and making individual interpretations as you seem to think, the follow on money would have dried up long ago.
Well damn it - now you've piqued my curiosity again. You didn't cite NIST - a citation is a specific reference to a published work - all you did was claim you got your interpretation from them. However, if you would care to cite something specific from NIST then I'd be happy to take a look at it and explain why it doesn't support your position.
We really are back to the same thing I complained about earlier - I'm giving detailed mathematical proofs while you are busy dismissing them, without any specific criticism, and instead just throwing around unsubstantiated assertions, misusing physics terms and principles, and now name dropping.
But hey - no worries - as long as you are well funded, who cares if you know what you are talking about.
You want some actual citations?
A fairly comprehensive historical description of measurement of local acceleration due to gravity from the National Bureau of Standards:
And even though you don't like Wikipedia, at least when it disagrees with you, how about the Wikipedia page on standard gravity that spells out in very plain English in the second paragraph (no need to worry about understanding equations as we've established you don't do math) that you are wrong about the correct meaning of g - it is the local value that takes into account centripetal acceleration due to the rotation of the earth.
Well damn it - now you've piqued my curiosity again. You didn't cite NIST - a citation is a specific reference to a published work - all you did was claim you got your interpretation from them. However, if you would care to cite something specific from NIST then I'd be happy to take a look at it and explain why it doesn't support your position.
Well I did, but when I lost my edit window apparently I didn't get it in the second time around, it was supposed to be in the last sentence of 145.
Quote:
Originally Posted by muppetry
We really are back to the same thing I complained about earlier - I'm giving detailed mathematical proofs while you are busy dismissing them, without any specific criticism, and instead just throwing around unsubstantiated assertions, misusing physics terms and principles, and now name dropping.
But hey - no worries - as long as you are well funded, who cares if you know what you are talking about.
You want some actual citations?
A fairly comprehensive historical description of measurement of local acceleration due to gravity from the National Bureau of Standards:
And even though you don't like Wikipedia, at least when it disagrees with you, how about the Wikipedia page on standard gravity that spells out in very plain English in the second paragraph (no need to worry about understanding equations as we've established you don't do math) that you are wrong about the correct meaning of g - it is the local value that takes into account centripetal acceleration due to the rotation of the earth.
And all that only says what I have been saying all along; but you refuse to accept gravity is gravity, and the other forces are other forces. You then trot out lots of additional acceleration issues that add up to apparent gravity and then call that gravity. which it isn't.
The Precise Measurement of Mass reference's principles are the same basic ones used for the lunar mission I mentioned earlier where you use knowledge of the centripetal accelerations to isolate the actual gravity. Boynton even used this quote "This example is for the gravitational attraction only and doesn’t include effect of centrifugal force due to earth’s rotation." He then goes on to use that as a starting point in his scale calibrations for location.
EXACTLY the same concept I have been saying all along. Repeatedly.
What part of your own reference is so non-standard that it is what I (in all my supposed non-standard interpretations by your description) have been saying all along?
The other ref link is broken so I won't be able to show how that agrees with me as well.
And OBTW: cheap shots don't prove your point at all.
Well I did, but when I lost my edit window apparently I didn't get it in the second time around, it was supposed to be in the last sentence of 145.
No problem. So where is it? You still haven't given it.
Quote:
Originally Posted by Hiro
And all that only says what I have been saying all along; but you refuse to accept gravity is gravity, and the other forces are other forces. You then trot out lots of additional acceleration issues that add up to apparent gravity and then call that gravity. which it isn't.
Good grief - are you really that obtuse? No it doesn't, and there are no other forces. How many times do I have to make that point? I worked purely in an inertial frame of reference in which there is no centrifugal force. There is only the attraction due to gravity, and then the residual part of it that is left to be measured as weight after some has been used to maintain circular motion.
Quote:
Originally Posted by Hiro
The Precise Measurement of Mass reference's principles are the same basic ones used for the lunar mission I mentioned earlier where you use knowledge of the centripetal accelerations to isolate the actual gravity. Boynton even used this quote "This example is for the gravitational attraction only and doesn’t include effect of centrifugal force due to earth’s rotation." He then goes on to use that as a starting point in his scale calibrations for location.
And then he explains why you have to take into account the variation of g with location (including rotation) to calibrate your scales to get a consistent value for mass. Note that carefully - variation with location taking into account all effects, including rotation - the entire discussion, encapsulated in that one observation.
In any case - you just demonstrated, I think, that you understand this concept just fine when you quoted "use knowledge of the centripetal accelerations to isolate the actual gravity". That clearly indicates that you realize that the acceleration due to gravity measured on the surface of any rotating body is modified by that rotation.
So let me ask one last simple question - would you agree that except on the axis of rotation (i.e. near the poles) the acceleration towards the surface of the earth of an object when it is dropped is dependent on the gravitational field strength, latitude, and the rotation of the earth? And that the normal reaction between a mass and the surface of the earth (i.e. its weight) depend on the same quantities?
If we don't disagree about that (despite that fact that you have denied it repeatedly), then is your entire problem just centered on whether the symbol g is used to mean locally measured acceleration due to gravity or local gravitational field strength? You do understand that simple distinction, don't you? And you do recognize that I defined right at the outset what I meant by g, consistent with the definition in most texts (although I will say for completeness that I do have one 1971 text on mechanics that breaks that convention and uses g sub e to mean effective local acceleration due to gravity) and consistent with the original discussion in this thread.
Quote:
Originally Posted by Hiro
EXACTLY the same concept I have been saying all along. Repeatedly.
EXACTLY the opposite of what you have been saying all along. Repeatedly.
Quote:
Originally Posted by Hiro
What part of your own reference is so non-standard that it is what I (in all my supposed non-standard interpretations by your description) have been saying all along?
Er, what? My objections to your "interpretations" arise when you make statements such as that the validity of the equivalence principle is not universal (it is), or that sensitive enough measurements can detect the difference (they can't, by definition), or that it is some kind of subset of d'Alembert's principle (it's not), or when you try to obfuscate (I assume that is your intent) by using terms borrowed from computing such as "abstraction level" that have absolutely no meaning in physics. I'm guessing your field is programming, although I'm still surprised that we have struggled so much to find a common language.
Quote:
Originally Posted by Hiro
The other ref link is broken so I won't be able to show how that agrees with me as well.
And OBTW: cheap shots don't prove your point at all.
Which cheap shots would those be? Referencing Wikipedia again? I notice you refrained from commenting on that. Or the comment about funding? Well then don't try to use the fact that you have funding to try to support a technical argument. It's completely irrelevant. Or the comment about math? You repeatedly dismissed my analyses without even checking the trivially simple derivations for the errors or invalid assumptions that presumably you must believe are there. What else should I conclude from that?
Anyway - I don't think there is much more I can add to this topic, so this time I really am done.
How many times do I have to make that point? I worked purely in an inertial frame of reference in which there is no centrifugal force.
And we are 180 out now where you are flipping use of the terms centrifugal and centripetal. I no longer have to self-chastize myself -- thanks! And how can you say there is no centripetal force in your calculations when you bring in the angular velocity vector ω? I have no response to that except to scratch my head.
Quote:
Originally Posted by muppetry
you realize that the acceleration due to gravity measured on the surface of any rotating body is modified by that rotation.
Given that statement I highlighted with boldface, there is no way to continue the conversation.
You either don't understand component forces, which you seem to understand just fine in your other explanations so I don't think that's it. Or you are really just blindly dug in that there is no difference between actual the gravitational pull of the involved masses compared to the apparent gravity on the surface of a rotating body which combines the gravitational pull between the masses with the effects of the centripetal accelerations.
Either way, there is absolutely nothing anyone on this Earth or any other celestial body in the Universe could say that reconciles with either of those issues.
And we are 180 out now where you are flipping use of the terms centrifugal and centripetal. I no longer have to self-chastize myself -- thanks! And how can you say there is no centripetal force in your calculations when you bring in the angular velocity vector ω? I have no response to that except to scratch my head.
Given that statement I highlighted with boldface, there is no way to continue the conversation.
You either don't understand component forces, which you seem to understand just fine in your other explanations so I don't think that's it. Or you are really just blindly dug in that there is no difference between actual the gravitational pull of the involved masses compared to the apparent gravity on the surface of a rotating body which combines the gravitational pull between the masses with the effects of the centripetal accelerations.
Either way, there is absolutely nothing anyone on this Earth or any other celestial body in the Universe could say that reconciles with either of those issues.
Once again, you didn't address even a single point I raised in my last post, and instead posted another raft of random bullshit and strawman arguments. So agreed. We are done.
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Comments
Maybe we can pause right there. All along I have talked only about gravity. Weight is not gravity, weight is the result of a mass accelerated (pulled even if unmoving) by gravity and other forces (centripetal being one) at the Earth's (Moons, etc. ...) surface. That is also roughly the Apparent Gravity discussion on the Wikipedia gravity page.
All along I have only held that those extra force components of Apparent Gravity are not Gravity, just a composite/resultant force that is very close to the actual force of gravity. That is why I keep saying as far as gravity goes I don't care about the centripetal accelerations.
Well I'm glad that we are finally getting there, but I did offer this explanation of the disagreement back in #116, and you rejected it outright. Although there are no extra forces involved. I wish you would stop saying that. Never mind. See below.
And that directly extends to weight, which rolls back around to where this all started -- the mess over pounds as mass, pounds as weight (and my snide eventual comment about pounds as currency) and the various early posters seemingly willing to ignore they were dealing with an overloaded term.
I won't disagree that other posters became muddled on this - that is why I joined the discussion - and I liked your currency comment.
The remainder of your post looks mostly OK, up until you call your g the gravity we use on Earth. Your g is not gravity, it is a version of apparent gravity (the interaction between gravity and ideal spherical centripetal acceleration).
It is those little slips in technical terminology precision that end up perpetuating the issue.
Thanks, but I disagree on two counts:
That's D'Alambert's Principle. It just makes the math easier, and unfortunately easier to safely miss-mash the math together. Convenient for a problem at a time, but the mis-mash methods are not necessarily good for generality. Better to save the vector combinations for as late in the evaluation as humanly possible.
No, it's not. It's Einstein's equivalence principle. D'Alembert's Principle (not D'Alambert's) is just a restatement of dynamic equilibrium in a constrained system, and does not mention the equivalence of acceleration and gravity. I've never had to resort to using it.
As for whether or not the gravity and the acceleration-at-a-point are are indistinguishable, that is a 'it depends' statement. To an observer standing on the ground with human senses, yes indistinguishable; to a gravitometer calibrated for lat/long and GPS altitude, no quite distinguishable*. Also they are very distinguishable when you are trying to do physical simulations. If you combine the equations algebraically as you have done the math gets ever more nasty when also doing body-body interactions. When you keep the components separated, use sensible local origins and use geometric methods the math is much simpler (though there are more discrete operations), it's also easier to program and extend for more generality (especially important when you don't know what the next question for the sim will be). Seeing as I'm very involved in the latter issues, the side of 'it depends' I fall on defaults to separate components rather than combined far less flexible solutions (try to dynamically simulate something as simple as long range rocket assisted sensor platform delivery using your combined apparent gravity equation compared to by-component methods).
No, there is no "it depends" about it. That particular equivalence principle is completely universal and has no caveats other than the one I quoted (infinitesimally small observer). I have no idea where you got that from, or what you mean by "they are very distinguishable when you are trying to do physical simulations", or where you are going at all with the rest of that comment for that matter, but I would be curious to know. Either you misunderstood my statement of the principle, your simulations are badly flawed, or I am completely missing your point.
We should be, it's just a case of say what we mean, mean what we say. Not something almost and incredibly close to like we mean or say. It's just about maintaining discipline when using terminology and I see great benefit with precise use of terminology.
Here I agree entirely, but would point out that I was very careful to define all terms from the outset, made no assumptions or approximations, and dealt only in idealized physics. If you are going to demand precision, you might want to review your own posts. If our original disagreement is just field strength versus local acceleration / weight, then I think that we have resolved that, leaving just the other details that I addressed above.
It has been interesting reading both of your arguments. I think you've actually been arguing over the definition of the word weight. One wants it to refer to the force of attraction between two bodies based on mass. The other wants it to refer to the reading on a scale set on the surface of the earth.
Well maybe, but more by implication, since Hiro never explicitly disputed it. However, weight is defined as mg and obviously m is invariant with location. So if g does not include all location-dependent factors the factors that affect weight, then either the definition of weight is incorrect, or it is not what we measure on a scale. I doubt anyone would argue the latter, but I've learned not to be surprised at anything I read here.
It is clear to me that Hiro wants g to be used purely to mean the gravitational field strength of the earth - in which case he is correct - it is position dependent only due to the oblateness of the earth, and independent of rotation. But while that is a perfectly valid quantity, the whole argument arose because the precise definition of weight requires a different value for g - the one that I derived that does take into account rotation. That this is correct is trivially obvious; in addition to the very simple but rigorous derivation that I gave, it is covered in countless basic physics texts and even the entry entitled "Gravity of Earth" on the ever-controversial Wikipedia. It is a little unfortunate that Wikipedia screws up the explanation by introducing a centrifugal force (which is nonetheless valid in the less elegant rotating frame of reference), but I think it is just trying to explain it in lay terms.
Anyway, I think the basic disagreement is pretty much resolved.
Well I'm glad that we are finally getting there, but I did offer this explanation of the disagreement back in #116, and you rejected it outright. Although there are no extra forces involved. I wish you would stop saying that. Never mind. See below.
As for 116 you are reading what you want to see, not what I said. I dismissed the majority of your post precisely because it was about the mathematical contributions of centripetal force. Not gravity. so no need for me to respond to it in detail at all.
Mostly OK? Meaning not completely? Don't make that statement without backing it up with specific criticism.
[*]There is no imprecision in that use of g; even though it has been used both to describe the earth's standard gravity (which itself is an average that takes into account rotation) and the local variable value, I defined my use of it as the latter at the outset, so neither imprecise nor ambiguous. I have never seen it used to describe local field strength, which appears to be your preferred definition, but perhaps you can provide a citation for that use. [/LIST]
I did. Which you apparently don't like because I don't agree with the use of g and calling that gravity in your text. The web is also muddled on the topic so most links are irrelevant, I happen to agree with NIST. And I wasn't grading for partial credit so I'm more than willing to say OK on the math without having examined it to the point I would vouch for it. That's not a cut, that's more like I trust you didn't screw up the basics.
No, it's not. It's Einstein's equivalence principle. D'Alembert's Principle (not D'Alambert's) is just a restatement of dynamic equilibrium in a constrained system, and does not mention the equivalence of acceleration and gravity. I've never had to resort to using it.
Well we can agree to disagree how to interpret your statements, because on my reading I do see those, I'm not going to argue that your view is wrong because it isn't, it's just at a different abstraction level that derives from the same first principles which is where D'Alembert comes in at a lower level that Einstein (name spelling error inconsequential unless you are trying to be a puffery about it).
No, there is no "it depends" about it. That particular equivalence principle is completely universal and has no caveats other than the one I quoted (infinitesimally small observer). I have no idea where you got that from, or what you mean by "they are very distinguishable when you are trying to do physical simulations", or where you are going at all with the rest of that comment for that matter, but I would be curious to know. Either you misunderstood my statement of the principle, your simulations are badly flawed, or I am completely missing your point.
I think you are really missing the point. The sim is well regarded. Not worth arguing over implementation that works, it does and many folks hate the geometric formulations because it's not what is taught in Physics 101, but they make almost everything soooo much simpler.
Strange stuff in a language I don't understand, but that certainly isn't physics...
We seem to have regressed again, and are probably on the wrong side of the law of diminishing return. Many might say we were there days ago, but perseverance is a virtue isn't it?
Let's just agree to differ then. I'm still frustrated that you never addressed any of my arguments with anything resembling technical responses, even when goaded to do so, but still had the nerve to accuse me of lack of precision and technical understanding. Your prerogative though, to use whatever form of argument works best for you. One of the good and bad things about the internet forum is that, in the end, there is no way to prevail in the face of single-minded and determined opposition. I failed miserably to convince you that mathematics and physics trump all else, and, not surprisingly, you failed to convince me that we should regard the basic laws of physics as fuzzy and open to our individual interpretation. At least that's how I read it.
With your permission I'd like to declare this horse fully expired, or feel free to take a parting shot and do the honors yourself.
Until next time...
you failed to convince me that we should regard the basic laws of physics as fuzzy and open to our individual interpretation. At least that's how I read it.
Yes the horse is dead, but only because you have decided that if it isn't said exactly how you want to frame it it becomes "fuzzy and open to our individual interpretation" -- even when I cite the National Institute of Standards and Technology as the source of the interpretation I'm going by-- I guess that puts your last statement in total perspective...
I don't need the internet forums to validate my ego, I'll happily continue to let the research contracts/sponsorships be my validation. If I really was as fuzzy and making individual interpretations as you seem to think, the follow on money would have dried up long ago.
Yes the horse is dead, but only because you have decided that if it isn't said exactly how you want to frame it it becomes "fuzzy and open to our individual interpretation" -- even when I cite the National Institute of Standards and Technology as the source of the interpretation I'm going by-- I guess that puts your last statement in total perspective...
I don't need the internet forums to validate my ego, I'll happily continue to let the research contracts/sponsorships be my validation. If I really was as fuzzy and making individual interpretations as you seem to think, the follow on money would have dried up long ago.
Well damn it - now you've piqued my curiosity again. You didn't cite NIST - a citation is a specific reference to a published work - all you did was claim you got your interpretation from them. However, if you would care to cite something specific from NIST then I'd be happy to take a look at it and explain why it doesn't support your position.
We really are back to the same thing I complained about earlier - I'm giving detailed mathematical proofs while you are busy dismissing them, without any specific criticism, and instead just throwing around unsubstantiated assertions, misusing physics terms and principles, and now name dropping.
But hey - no worries - as long as you are well funded, who cares if you know what you are talking about.
You want some actual citations?
A fairly comprehensive historical description of measurement of local acceleration due to gravity from the National Bureau of Standards:
J. Res. Nat. Bur. Stand. Sec. C: Eng. Inst., Vol. 72C, No. 1, p. 1
A conference paper that describes quite concisely why this matters:
http://www.space-electronics.com/Lit...nt_of_Mass.PDF
And even though you don't like Wikipedia, at least when it disagrees with you, how about the Wikipedia page on standard gravity that spells out in very plain English in the second paragraph (no need to worry about understanding equations as we've established you don't do math) that you are wrong about the correct meaning of g - it is the local value that takes into account centripetal acceleration due to the rotation of the earth.
Well damn it - now you've piqued my curiosity again. You didn't cite NIST - a citation is a specific reference to a published work - all you did was claim you got your interpretation from them. However, if you would care to cite something specific from NIST then I'd be happy to take a look at it and explain why it doesn't support your position.
Well I did, but when I lost my edit window apparently I didn't get it in the second time around, it was supposed to be in the last sentence of 145.
We really are back to the same thing I complained about earlier - I'm giving detailed mathematical proofs while you are busy dismissing them, without any specific criticism, and instead just throwing around unsubstantiated assertions, misusing physics terms and principles, and now name dropping.
But hey - no worries - as long as you are well funded, who cares if you know what you are talking about.
You want some actual citations?
A fairly comprehensive historical description of measurement of local acceleration due to gravity from the National Bureau of Standards:
J. Res. Nat. Bur. Stand. Sec. C: Eng. Inst., Vol. 72C, No. 1, p. 1
A conference paper that describes quite concisely why this matters:
http://www.space-electronics.com/Lit...nt_of_Mass.PDF
And even though you don't like Wikipedia, at least when it disagrees with you, how about the Wikipedia page on standard gravity that spells out in very plain English in the second paragraph (no need to worry about understanding equations as we've established you don't do math) that you are wrong about the correct meaning of g - it is the local value that takes into account centripetal acceleration due to the rotation of the earth.
And all that only says what I have been saying all along; but you refuse to accept gravity is gravity, and the other forces are other forces. You then trot out lots of additional acceleration issues that add up to apparent gravity and then call that gravity. which it isn't.
The Precise Measurement of Mass reference's principles are the same basic ones used for the lunar mission I mentioned earlier where you use knowledge of the centripetal accelerations to isolate the actual gravity. Boynton even used this quote "This example is for the gravitational attraction only and doesn’t include effect of centrifugal force due to earth’s rotation." He then goes on to use that as a starting point in his scale calibrations for location.
EXACTLY the same concept I have been saying all along. Repeatedly.
What part of your own reference is so non-standard that it is what I (in all my supposed non-standard interpretations by your description) have been saying all along?
The other ref link is broken so I won't be able to show how that agrees with me as well.
And OBTW: cheap shots don't prove your point at all.
Well I did, but when I lost my edit window apparently I didn't get it in the second time around, it was supposed to be in the last sentence of 145.
No problem. So where is it? You still haven't given it.
And all that only says what I have been saying all along; but you refuse to accept gravity is gravity, and the other forces are other forces. You then trot out lots of additional acceleration issues that add up to apparent gravity and then call that gravity. which it isn't.
Good grief - are you really that obtuse? No it doesn't, and there are no other forces. How many times do I have to make that point? I worked purely in an inertial frame of reference in which there is no centrifugal force. There is only the attraction due to gravity, and then the residual part of it that is left to be measured as weight after some has been used to maintain circular motion.
The Precise Measurement of Mass reference's principles are the same basic ones used for the lunar mission I mentioned earlier where you use knowledge of the centripetal accelerations to isolate the actual gravity. Boynton even used this quote "This example is for the gravitational attraction only and doesn’t include effect of centrifugal force due to earth’s rotation." He then goes on to use that as a starting point in his scale calibrations for location.
And then he explains why you have to take into account the variation of g with location (including rotation) to calibrate your scales to get a consistent value for mass. Note that carefully - variation with location taking into account all effects, including rotation - the entire discussion, encapsulated in that one observation.
In any case - you just demonstrated, I think, that you understand this concept just fine when you quoted "use knowledge of the centripetal accelerations to isolate the actual gravity". That clearly indicates that you realize that the acceleration due to gravity measured on the surface of any rotating body is modified by that rotation.
So let me ask one last simple question - would you agree that except on the axis of rotation (i.e. near the poles) the acceleration towards the surface of the earth of an object when it is dropped is dependent on the gravitational field strength, latitude, and the rotation of the earth? And that the normal reaction between a mass and the surface of the earth (i.e. its weight) depend on the same quantities?
If we don't disagree about that (despite that fact that you have denied it repeatedly), then is your entire problem just centered on whether the symbol g is used to mean locally measured acceleration due to gravity or local gravitational field strength? You do understand that simple distinction, don't you? And you do recognize that I defined right at the outset what I meant by g, consistent with the definition in most texts (although I will say for completeness that I do have one 1971 text on mechanics that breaks that convention and uses g sub e to mean effective local acceleration due to gravity) and consistent with the original discussion in this thread.
EXACTLY the same concept I have been saying all along. Repeatedly.
EXACTLY the opposite of what you have been saying all along. Repeatedly.
What part of your own reference is so non-standard that it is what I (in all my supposed non-standard interpretations by your description) have been saying all along?
Er, what? My objections to your "interpretations" arise when you make statements such as that the validity of the equivalence principle is not universal (it is), or that sensitive enough measurements can detect the difference (they can't, by definition), or that it is some kind of subset of d'Alembert's principle (it's not), or when you try to obfuscate (I assume that is your intent) by using terms borrowed from computing such as "abstraction level" that have absolutely no meaning in physics. I'm guessing your field is programming, although I'm still surprised that we have struggled so much to find a common language.
The other ref link is broken so I won't be able to show how that agrees with me as well.
Apologies - somehow truncated the URL.
And OBTW: cheap shots don't prove your point at all.
Which cheap shots would those be? Referencing Wikipedia again? I notice you refrained from commenting on that. Or the comment about funding? Well then don't try to use the fact that you have funding to try to support a technical argument. It's completely irrelevant. Or the comment about math? You repeatedly dismissed my analyses without even checking the trivially simple derivations for the errors or invalid assumptions that presumably you must believe are there. What else should I conclude from that?
Anyway - I don't think there is much more I can add to this topic, so this time I really am done.
How many times do I have to make that point? I worked purely in an inertial frame of reference in which there is no centrifugal force.
And we are 180 out now where you are flipping use of the terms centrifugal and centripetal. I no longer have to self-chastize myself -- thanks! And how can you say there is no centripetal force in your calculations when you bring in the angular velocity vector ω? I have no response to that except to scratch my head.
you realize that the acceleration due to gravity measured on the surface of any rotating body is modified by that rotation.
Given that statement I highlighted with boldface, there is no way to continue the conversation.
You either don't understand component forces, which you seem to understand just fine in your other explanations so I don't think that's it. Or you are really just blindly dug in that there is no difference between actual the gravitational pull of the involved masses compared to the apparent gravity on the surface of a rotating body which combines the gravitational pull between the masses with the effects of the centripetal accelerations.
Either way, there is absolutely nothing anyone on this Earth or any other celestial body in the Universe could say that reconciles with either of those issues.
And we are 180 out now where you are flipping use of the terms centrifugal and centripetal. I no longer have to self-chastize myself -- thanks! And how can you say there is no centripetal force in your calculations when you bring in the angular velocity vector ω? I have no response to that except to scratch my head.
Given that statement I highlighted with boldface, there is no way to continue the conversation.
You either don't understand component forces, which you seem to understand just fine in your other explanations so I don't think that's it. Or you are really just blindly dug in that there is no difference between actual the gravitational pull of the involved masses compared to the apparent gravity on the surface of a rotating body which combines the gravitational pull between the masses with the effects of the centripetal accelerations.
Either way, there is absolutely nothing anyone on this Earth or any other celestial body in the Universe could say that reconciles with either of those issues.
Once again, you didn't address even a single point I raised in my last post, and instead posted another raft of random bullshit and strawman arguments. So agreed. We are done.
I don't think there is much more I can add to this topic, so this time I really am done.
You are? Could have fooled me!
<whinghing snipped> We are done.
Really now? Finally?
Too bad, I really wanted to see if you would take the next step and claim the forces involved in jumping prove anti-gravity.
@SolipsismX, did your popcorn maker get worn out yet?
Does Gorilla Glass Need Screen Protector?