Mendel
Senior Member.
The reactions speak for themselves.
I've explained the connection in post #4 https://www.metabunk.org/threads/falling-objects-can-be-faster-than-free-fall.13263/post-306232
Falling objects can be faster than free fall
- Thread starter Mendel
- Start date
- Status
I've explained the connection in post #4 https://www.metabunk.org/threads/falling-objects-can-be-faster-than-free-fall.13263/post-306232
Mendel
Senior Member.
Any bullet is (mostly) in free fall once it leaves the muzzle, with gravity and air resistance being the only forces acting on it. As such, no bullet moves "faster" than free-fall, irrespective of whether "faster" refers to velocity or acceleration. It merely has a high v0 (initial velocity) when it enters free-fall.
qed
Senior Member
So you are explaining why the building collapsed so close to free fall by pondering over g?
Am I correct? Surely not, because the correct thing to focus on is "why so close to free fall", not ponder over g?
[... edit .../
[... I am not even sure what claim we are debunking and why ...]
[... I have re-looked at the OP and see no referenced claim about WTC over g...]
For example, when we mark this thread (debunked) what will have been debunked?
Last edited:
Mendel
Senior Member.
This.
"Free-fall acceleration implies free fall", expressed as "Natural collapse resulting in free fall is simply not plausible" or "Basic principles of engineering ... would dictate that ... resist and slow the downward movement".
Oystein
Senior Member
This is similar to pondering why you never quit beating your wife: A loaded question.
I have said it many times, I will say it again:
The building never collapses "close to free fall". Even if you consider that the vaguery of the phrase "close to" gives you wiggle room.
At all times, the building is collapsing at significantly less than free fall (urrr I am sure you mean an acceleration equivalent to that of free fall, don't you?).
At most, some suitably chosen small bit of the building appears to move for a brief, suitably chosen time interval, and late into the collapse sequence with all the buckling that has already accumulated, at an acceleration that very nearly averages that of free fall.
Right?
I insist that speaking with precision is paramount here.
I suspect that anybody who uses careless wording like "the building", "close to" or "free fall" may be arguing in bad faith.
econ41
Senior Member
Fully agreed.
It is probable but not necessarily always so.
When seeking to explain a phenomenon that requires quantified data it can be that the data is not precise enough or sufficient to support a definitive conclusion.
Explaining the WTC7 collapse issues has been, still is, such a situation.
(1) The measurement data is not sufficient to conclude that there was "over G".
(2) But neither is there sufficient data to conclude the negative. That there was NO "over G".
(3) Since "over G" is a phenomenon that can occur there is no legitimate argument for excluding it from consideration.
And "close to" is a valid though unquantified description to adopt in such a process of exploration. All it says is that the range of possibilities are "close enough" to require factors to be considered including the need for more precise data.
econ41
Senior Member
Agreed. Those AE911 claims are false. To be specific they are "False Generalisations" in the form of false global claims. And they are routinely used by truthers in arguments that make the error of false dichotomy. If anyone wants "proof" many examples are available.
Last edited:
Marc Powell
Active Member
A simple explanation for the action seen in the video is that neither rope ladder is truly falling at G. The entirety of the rope ladder on the right is being subjected to air resistance while the one on the left is having its air resistance progressively reduced as its rungs land on the table. The fact that the rungs are not horizontal is a red herring of no significance.
econ41
Senior Member
A nice attempt @Marc Powell. My thoughts are:
Certainly it is a better topic for challenging our thinking and reasoning skills than some of the other divergent subtopics.
And, for those who, like me are interested in the meta-process denial aspect littering this thread. It is in logical process the same situation as those arguments claiming that "over G" can be dismissed from consideration in WTC7 collapses. There isn't enough data or evidence to warrant disregarding the issues. It doesn't need "proof" that it is a factor. It needs proof that it is NOT. << Some lovely irony for those who may appreciate it.
Good thinking. Worthy of discussion. I suspect that it is negated because all factors on the left are reducing proportionately as the rungs cease to be involved. So the falling weight is also reducing, countering the reduced air resistance? And, at this stage, I haven't a clue as to a full comprehensive analysis - YET!!. So, once again I'll take the risk. It looks "close enough" to offer a case to answer as the lawyers would state it.
Certainly it is a better topic for challenging our thinking and reasoning skills than some of the other divergent subtopics.
I'll challenge you back with that one. Each rung, as it impacts is the same tilting beam model as the several times referenced ball into cup proof of "over G". So, if you want to argue that it is not relevant, I suggest the burden of proof is yours. Go for it.
And, for those who, like me are interested in the meta-process denial aspect littering this thread. It is in logical process the same situation as those arguments claiming that "over G" can be dismissed from consideration in WTC7 collapses. There isn't enough data or evidence to warrant disregarding the issues. It doesn't need "proof" that it is a factor. It needs proof that it is NOT. << Some lovely irony for those who may appreciate it.
Last edited:
qed
Senior Member
But that has nothing to do with over g! It has all to do with free fall, resistance and close to g. Nothing to do with over g.
Why over g in the title of the post? Why all the discussion on over g rather than close to g?
What will we mark as (debunked)?
Last edited:
qed
Senior Member
If you have read any of my posts, you will know I mean the right corner of the penthouse. I have performed femr2's calculations.
Mendel
Senior Member.
• The "over g" is in the title of the post because the ladder clip demonstrates it.
• If an object can "fall at over g" when not being in free fall, it can obviously also fall at (or "close to") g when not being in free fall. This contradicts the AE911 claims I quoted above.
• I am not responsible for the "over g" WTC discussion.
• The claim in the title is true, I provided evidence for it. It won't be marked as debunked, nor does it need to be.
• I did it that way because that fact can be used to debunk several truther claims, but a Metabunk thread needs to be focused on a single claim of evidence.
Mendel
Senior Member.
Air resistance depends mainly on an object's cross-section perpendicular to the air flow.
In fact, a long object has proportionally less air resistance than a short object. Trains would be a good example, as the carriages essentially ride in the slipstream of the train engine.
Article: 
Thus, a long ladder should fall faster than a short ladder, all else being equal.
That contradicts your hypothesis.
You shouldn't dismiss the argument relating to that without grounds.
Marc Powell
Active Member
In my first response, I was trying to be brief. The longer version of my theory is that, while falling vertically, the multiple rungs of the ladder create a column of turbulent air which translates to drag. As the rungs of the ladder on the left land on the table the turbulence progressively decreases allowing the remaining rungs to fall through progressively cleaner air. Weight reduction is not a factor, and because strings do not transmit compressive loads, nor is what happens to the rungs as they haphazardly carom off the table. The diagonal orientation of the rungs may have some minor effect on the amount of turbulence generated as the ladders fall, but since both rope ladders have rungs with similar orientation, that also should not be a factor.A nice attempt @Marc Powell. My thoughts are:
Good thinking. Worthy of discussion. I suspect that it is negated because all factors on the left are reducing proportionately as the rungs cease to be involved. So the falling weight is also reducing, countering the reduced air resistance? And, at this stage, I haven't a clue as to a full comprehensive analysis - YET!!. So, once again I'll take the risk. It looks "close enough" to offer a case to answer as the lawyers would state it.
Certainly it is a better topic for challenging our thinking and reasoning skills than some of the other divergent subtopics.
I'll challenge you back with that one. Each rung, as it impacts is the same tilting beam model as the several times referenced ball into cup proof of "over G". So, if you want to argue that it is not relevant, I suggest the burden of proof is yours. Go for it.
And, for those who, like me are interested in the meta-process denial aspect littering this thread. It is in logical process the same situation as those arguments claiming that "over G" can be dismissed from consideration in WTC7 collapses. There isn't enough data or evidence to warrant disregarding the issues. It doesn't need "proof" that it is a factor. It needs proof that it is NOT. << Some lovely irony for those who may appreciate it.
Mendel
Senior Member.
A single rung falling already does that.
econ41
Senior Member
Thanks for the response @Marc Powell. I'll comment on two aspects.
First:
Second: Take care that you don't pre-emptively discard the comparison I referred to:
First:
Essentially you are moving to quantify the air resistance - a path worthy of consideration because without quantification we cannot dismiss the effect. I note that @Mendel has responded to that aspect. Let's see where the discussion goes.
Second: Take care that you don't pre-emptively discard the comparison I referred to:
That diagonal 'slope' sets up each successive rung to impact at one end whilst the Centre-of-Mass continues to fall with near g acceleration thereby "flicking" the higher end of the rung to accelerate at more than g. True the rope cannot transmit compression but the pull-down on the rope is tension. Giving a bit of impetus to increase the acceleration of all the rungs still above that level.
Plausible - a factor needing further analysis.
Marc Powell
Active Member
If each rung was analyzed as a single body producing drag while falling through a laminar air flow, then rope ladders of any length would fall at equal accelerations and attain equal terminal velocities. However, my theory is that the air vortices of the rungs interact so as to generate greater turbulence the longer the ladder is. Therefore, a shorter ladder will produce less drag and accelerate to a higher terminal velocity more quickly than will a longer ladder.Air resistance depends mainly on an object's cross-section perpendicular to the air flow.
In fact, a long object has proportionally less air resistance than a short object. Trains would be a good example, as the carriages essentially ride in the slipstream of the train engine.
Article:
Thus, a long ladder should fall faster than a short ladder, all else being equal.
That contradicts your hypothesis.
You shouldn't dismiss the argument relating to that without grounds.
Marc Powell
Active Member
Thank you. Your explanation was illuminating. After giving the situation some thought, I think I can see how the diagonal orientation of each rung as it impacts the table would produce tensile forces in the rope that cause the remaining rungs above to fall progressively faster. So, the orientation of the rungs actually does have significance and air resistance may be only a minor issue. It would be interesting to see the experiment with rope ladders carried out in a vacuum to check if air resistance is actually of any significance.
econ41
Senior Member
No problem.
My engineers experienced bare assertion gut feeling says air resistance is less significant if, in fact, it is even in the ballpark.
But, following the recurring derail theme in this thread, I cannot prove that it should be discounted.
Mendel
Senior Member.
Yes. That's counterfactual.
A single rung creates turbulence. The second rung rides in the first rung's turbulence and adds very little to it. The diagram I've quoted underscores this.
You severely underestimate the size and length of turbulent trail that a single object generates.
Do not trust your intuition if you can't back it up with evidence!
Isn't the thread title kind of... obvious? The ladder is going faster than g sure, but it's not just falling. It's falling and being tugged down by the rungs being flattened on impact. That's two downward forces, not just gravity, so obviously it goes faster than g.
As for how all this relates to 9/11, there's a lot of talk about "free fall" means. The OP says the ladder is not in free fall because it's impacting a table. But what is and isn't "free fall" is kind of besides the point when it comes to WTC 7. Was WTC 7 ever in some perfect, idealized form of pure free fall? No. For one, there was obviously air resistance. But what if we discount air resistance? Still no. Obviously in the collapse of a complex structure, there's going to be thousands and thousands of tiny parts hitting each other and causing resistance. But because the most important vertical supports had been suddenly and simultaneously removed, the net resistance created by those impacts was negligible compared to the weight bearing down on them. This amounted to a 9.8 m/s^2 downward acceleration.
It's like if you drop a piano on a feather. As the piano impacts the feather, is it technically in "free fall"? No, it's downward movement is being resisted by the feather. But the effect is so small it's not noticeable.
As for how all this relates to 9/11, there's a lot of talk about "free fall" means. The OP says the ladder is not in free fall because it's impacting a table. But what is and isn't "free fall" is kind of besides the point when it comes to WTC 7. Was WTC 7 ever in some perfect, idealized form of pure free fall? No. For one, there was obviously air resistance. But what if we discount air resistance? Still no. Obviously in the collapse of a complex structure, there's going to be thousands and thousands of tiny parts hitting each other and causing resistance. But because the most important vertical supports had been suddenly and simultaneously removed, the net resistance created by those impacts was negligible compared to the weight bearing down on them. This amounted to a 9.8 m/s^2 downward acceleration.
It's like if you drop a piano on a feather. As the piano impacts the feather, is it technically in "free fall"? No, it's downward movement is being resisted by the feather. But the effect is so small it's not noticeable.
benthamitemetric
Senior Member
I agree with @qed that there is no dispositive evidence of over-g acceleration for any portion of the WTC buildings during their recorded collapses. And if this thread were posted to present a claim that there is evidence of over-g acceleration for a portion of the WTC buildings during their recorded collapses, it could thus be concluded.
But the OP does not present such a claim. Instead, @Mendel's claim was limited:
I don't think these claims are bunk and they are worthy of some note (if for no other reason than that every other aspect of those collapses has been beaten to death with no new noteworthy bunk coming to the fore in years), even if they are second- or third-level considerations in the context of observations of the WTC buildings' collapses. Since the effect noted by @Mendel could affect a portion of the building without accelerating it to over-g (e.g., it could be that a portion of the building that would have collapsed with an average acceleration over some period of time that would have been equal to 0.8g based purely on the resistance imparted by structural components below it instead collapsed with an average acceleration over such period of time equal to g based on some mechanical force imparted by part of the structure to which it was attached), it must be factored into any analysis that purports to draw a conclusion based on the observed acceleration of any portion of the buildings over any period of time.
Though valiant efforts in subpixel tracking have been utilized in past discussions of this point to try to nail down whether over-g accelerations are actually observable in the WTC collapses (which would be significant only in that it would prove that a mechanical acceleration had been imparted to some facet of the building during some moment in the collapse, which itself isn't highly significant because the existence of such forces at many places within such a complicated collapse should not be in doubt), it seems the data set available (i.e., the video) is either too noisy to be conclusive with methods employed today or does not evince any such accelerations.
But the OP does not present such a claim. Instead, @Mendel's claim was limited:
I don't think these claims are bunk and they are worthy of some note (if for no other reason than that every other aspect of those collapses has been beaten to death with no new noteworthy bunk coming to the fore in years), even if they are second- or third-level considerations in the context of observations of the WTC buildings' collapses. Since the effect noted by @Mendel could affect a portion of the building without accelerating it to over-g (e.g., it could be that a portion of the building that would have collapsed with an average acceleration over some period of time that would have been equal to 0.8g based purely on the resistance imparted by structural components below it instead collapsed with an average acceleration over such period of time equal to g based on some mechanical force imparted by part of the structure to which it was attached), it must be factored into any analysis that purports to draw a conclusion based on the observed acceleration of any portion of the buildings over any period of time.
Though valiant efforts in subpixel tracking have been utilized in past discussions of this point to try to nail down whether over-g accelerations are actually observable in the WTC collapses (which would be significant only in that it would prove that a mechanical acceleration had been imparted to some facet of the building during some moment in the collapse, which itself isn't highly significant because the existence of such forces at many places within such a complicated collapse should not be in doubt), it seems the data set available (i.e., the video) is either too noisy to be conclusive with methods employed today or does not evince any such accelerations.
qed
Senior Member
@benthamitemetric The reason why I disagree with you is that @Mendel has clarified the CT claims he believes the OP debunks.
qed
Senior Member
Should we not move the two quoted claims into the OP?
And then tighten to OP to show exactly how the over-g argument debunks this?
[... especially given that is is currently a front-facing 9-11 thread ...]
And then tighten to OP to show exactly how the over-g argument debunks this?
[... especially given that is is currently a front-facing 9-11 thread ...]
Last edited:
econ41
Senior Member
Yes, it should be obvious. And your reasoning is correct.
There are other points in the remainder of your post that are worthy of discussion but are too far off-topic to pursue here.
The relevance to WTC7 is that "over G" is plausible and has to be considered in the WTC7 scenario. We are seeing one error of logic repeated. The reality that we cannot prove that "over g" was involved in the WTC7 collapse does NOT prove that it was NOT a factor. "Cannot prove it is X" DOES NOT prove "It was not X". It is a common error seen in truth movement claims and debunking.
qed
Senior Member
qed
Senior Member
Why is CD not plausible?
qed
Senior Member
Surely implicit is the cause of over g?
qed
Senior Member
What is the evidence for "over g" in WTC7? WTC1? WTC2?
FatPhil
Senior Member.
Well, the reality of those two noun phrases is that "over G" represents a measurement of what actually happened, and that "controlled demolition" is a hypothesis grounded on no evidence at all. One is a concrete result, the other is an abstract concept. There's still no equivalence.
Even if you need to bootstrap the "over g" concept, you're only the tiniest step away from returning to common sense: a perfectly mundane cause of over-g acceleration is subcomponents rotating. We've seen tipping and twisting, therefore this potential cause is supported by evidence. If you want to propose another cause, you are going to have to provide equally undeniable evidence for it. The tipping and twisting, of course, are also *effects*, and so this extra step back has achieved nothing. The equivalence between the paragraphs still doesn't hold.
qed
Senior Member
I really don't get you, over G was never measured nor its cause stated, he said its was "plausible". Surely so is CD in some form?
I stand to be corrected.
FatPhil
Senior Member.
At-or-around-g certainly was measured, see Henkka's post https://www.metabunk.org/threads/falling-objects-can-be-faster-than-free-fall.13263/post-306403 , Figure 3.15 from the NIST report.
Mundane, if somewhat unexpected, causes being able to explain a more extreme result ("over g" is attainable) implies that mundane causes are able to explain a weaker result ("at g" is attainable). Measurements of the weaker result have been made (NIST). A claim that the weaker result is impossible without a non-mundane cause have been made (ae911truth). But the stronger and therefore the weaker result being demonstrable from mundane causes debunks that claim.
End Of Thread. As it should have been 5 pages back.
qed
Senior Member
qed
Senior Member
Why in 9-11, that is inviting trouble! I see no relation.
- Status
Similar threads
