Falling objects can be faster than free fall

[Mendel]

According to Youtube comments, it seems the answer to the rope ladder is that because the rungs are angled, hitting the table causes them to flatten, which creates a slight downward pull on the above rungs. I'm no expert though, this is just what the comments are saying. But I don't see how it's applicable to the WTC collapses, or specifically WTC 7, since that was the one in free fall.

Nobody claims it's applicable to the WTC directly. There is no data (and no software) to accurately simulate these collapses, so there's no way to make such a claim with evidence.

The ladder experiment is meant to disperse the incredulity that is used to claim that a free-fall-like acceleration must mean free fall with no resistance, because it does not.

There are various mechanical ways to effect a gravity-powered acceleration in excess of 1g, and it's quite possible that the damaged steel frame buildings exhibited some of them.

Other examples include
• a trebuchet
• a rod with one end supported and the rest freely falling

 

[Oystein]

You're splitting hairs...

No. Not at all. YOu failed to grasp the core message.

What I try to explain - but you either completely fail to understand or consciously ignore - is a very fundamental considerastion: That the basic Laws of Conversation in physics - Conversation of Energy, Conversation of Momentum - apply only to a closed system, not to parts of a closed system.

The closed system that you must consider is, in its simplest form, the entire building resting on a planet that can be, for practical purposes, considered as having unlimited mass. While it is true that the building, as it is progressively destroyed, continuously sucks up part of the potential energy and therefore the motion of "The Building" must at all times be at less than gravitational acceleration relative to earth, this is most emphatically NOT true for PARTS of the building, or the system.

This is what we're talking about:


Source: https://www.youtube.com/watch?v=aBYoKEbIIBg

The roofline starts to descend about 10 seconds into the video.

This is AFTER all of the core has already started to descend, right? After a lot of internal destruction has already occurred, right? After the wall has lost most of its lateral support, right? So what we are talking about is merely a short interval of time occurring late into the collapse sequence, right?

For the first 100 feet of the fall, the roofline is going at 9.8 m/s^2.

Unproven, and very certainly FALSE.
For a suitably chosen time interval that probably starts a bit AFTER the roofline started to descend, its motion averaged 9.8 m/s^2 squared, which equivalent to g, right?

But - is it constant during that interval?
Probably, demonstrably, no. During a sub-part of that interval, acceleration is >g, and for other parts of the interval, therefore, acceleration is <g.
Both results prove the roofline is NOT "in freefall". It proves the roofline experiences both downward forces (the OP video demonstrates one possible mechanism for this) and residual upward forces in addition to gravity.
Right?

This lasts for about two seconds.

If you plot acceleration vs time, there is nothing in that graph that "lasts for about two seconds". Acceleration increases, decreases, increases again, decreases again along an irregular path. It is never straight and horizontal.
The about two second interval is arbitrarily chosen for the conscious purpose of having it average g.

To describe what everyone can plainly see in the video as "Only a SMALL PART of WTC7" feels like gaslighting and feels like you're being overly defensive.

But it isn't. See the fundamental remark at the beginning of this post: You cannot, in a chaotic event like a highrise collapse, take the motion of an arbitrarly chosen point on the object and treat it as representative of the whole object. IT ISN'T.

Like the debunker doth protest too much. Sure it's the north wall, but that's because that's the only wall we can see in the video!

How do you know you't observe the same on the other walls? You make up stuff.

Well, we can see the northwest wall also, and it's falling just the same.

You mean the West wall?
I would love to see your tracking and measuring of the West wall ... roofline, I suppose

There's no reason to think the walls we can't see are doing something radically different.

But there is every reason to think the CORE is doing something "radically" different. (Like running into the ground).

Anyway, it is pretty unimportant what the other walls do:

The walls are only a part of the structure, and the OP experiment demonstrates how a part of a structure can fall at >g even (and especially!) as it runs into resistance from below.
You cannot deny that, because you have seen the video.

 

[Mendel]

The about two second interval is arbitrarily chosen for the conscious purpose of having it average g.

Cherry-picking data, right out of the pseudoscience cookbook.

You cannot deny that, because you have seen the video.

But they can detract from it.

"Freefall acceleration proves no resistance" is not a credible argument once you've seen this experiment. (It was never valid.)

 

[Gamolon]

Just so we're on the same page. AE911Truth (as many other skeptics) usually cite NIST for this:

https://www.ae911truth.org/evidence/near-free-fall-acceleration

Go watch the video Henkka posted in #39.

Just to be clear, the entire building did not fall at the same time, certain parts collapse at different times.

The east penthouse fell into the building first. Then about 7 seconds later the west penthouse started to collapse which was quickly followed by what was left of the building. You do see the west penthouse disappear behind the façade correct?

 

[Gamolon]

The roofline starts to descend about 10 seconds into the video. For the first 100 feet of the fall, the roofline is going at 9.8 m/s^2.

Not true. The roofline did not start in immediate freefall when it started to move downward. Go find graphs of the event and you'll see what I am talking about.

 

[Just Bruce]

In the 9/11 discussions, "free fall acceleration" is often treated as a kind of speed limit for gravity-driven falling objects. But that's a misconception. Watch this short video:

Source: https://youtube.com/watch?v=n8WxkqMRgS4

Because the ladder on the left impacts a table, it is no longer in free fall, and therefore mechanical effects can then cause acceleration or deceleration.

Nothing about the WTC collapses was free fall (excepting the parts ejected to the side that fell through clear air, which came close). Therefore, free fall acceleration is neither a necessity nor a limit.

I think if the runs where level, the ladders would fall at the same rate even if one was hitting the table. I think what is happening is that one end of a run hit first. This imposes an angular momentum around the center of mass for the run. Since the runs are rigid, an extra downward force is imposed on the string at the opposite end of the impact. This could be tested by slanting all of the runs the same direction and seeing if the high side of the ladder falls faster and truing it with the runs level to make the effect go away.

 

[Thomas B]

"Freefall acceleration proves no resistance" is not a credible argument once you've seen this experiment. (It was never valid.)

Does AE911T have to be more precise about the implications of "free fall" than NIST? If "Freefall acceleration proves no resistance" was "never valid", then surely Shyam Sunder's reasoning in that press conference they make so much is, at least on the face of it, invalid too?

“[A] free-fall time would be an object that has no structural components below it.... What the analysis shows...is that same time it took for the structural model to come down...is 5.4 seconds. It’s about 1.5 seconds, or roughly 40 percent, more time for that free fall to happen. And that is not at all unusual because there was structural resistance that was provided in this particular case.”

https://www.ae911truth.org/evidence/free-fall-acceleration

To me, this is where I think we're all (skeptics and debunkers) too far down the rabbit hole to make any progress. Once our debunking comes to depend on criticizing NIST's way of explaining the engineering principles we have lost the authority we need.

Here, I think the skeptic (and just the person who is curiously investigating these issues) is entitled to say that there is an important relationship between the acceleration of the collapse and the resistance the structure offered. That there are interesting physics experiments you can do to explore edge cases that challenge the absoluteness of the principle doesn't undermine the validity of the reasoning that finds "free fall" an interesting issue.

 

[Mendel]

Does AE911T have to be more precise about the implications of "free fall" than NIST? If "Freefall acceleration proves no resistance" was "never valid", then surely Shyam Sunder's reasoning in that press conference they make so much is, at least on the face of it, invalid too?

https://www.ae911truth.org/evidence/free-fall-acceleration

It's a cherry-picked quote without context, I don't see ae911truth link back to the actual press conference. Sunder's point is that it's not unusual for a collapse to be slower than free fall because of resistance. Now re-read my logic explainer above to understand why that is not the same as saying that resistance means slower collapse.
It's not invalid.

To me, this is where I think we're all (skeptics and debunkers) too far down the rabbit hole to make any progress. Once our debunking comes to depend on criticizing NIST's way of explaining the engineering principles we have lost the authority we need.

We don't need authority. If you do, that's on you.
The NIST report is great because it has collected evidence and analysis on collapse initiation for the WTC towers. They make a compelling case that the fires caused the collapse.
They did not analyse the progressive collapse phase because they did not have the means to do so, and because there is no need to.

Here, I think the skeptic (and just the person who is curiously investigating these issues) is entitled to say that there is an important relationship between the acceleration of the collapse and the resistance the structure offered.

What would that relationship be? Can you prove it?

That there are interesting physics experiments you can do to explore edge cases that challenge the absoluteness of the principle doesn't undermine the validity of the reasoning

What reasoning, exactly? Please be explicit.

that finds "free fall" an interesting issue.

Prove that free fall was involved, i.e. that the falling parts had no contact with other objects.
If you can't, "free fall" is a groundless speculation that violates common sense. If it wasn't involved, it's not interesting.


For WTC7, this is even more damning, because for the facade to have no contact with other objects implies that the interior of the building has already collapsed (as evidenced by the penthouses disappearing), which means any CD would have already taken place before the "freefall" even started. And that means the free fall can't be proof of it.


Like the truthers, you fail to follow the evidence.

 

[Thomas B]

It's a cherry-picked quote without context, I don't see ae911truth link back to the actual press conference.

This doesn't align with my memory of Chandler's careful analysis of the press conference. What context are you claiming is left out?

 

[Thomas B]

Like the truthers, you fail to follow the evidence.

Interesting point. And there's a sense in which it is correct. In my view, conspiracy theorists and debunkers alike are excessively obsessed with "facts" that they think can settle the questions, though they of course disagree about what counts as "evidence".

I am more concerned about fitting the facts (always somewhat in question) into a coherent world view, building a model of social and material reality that can make sense of what is going on.

I'm sure someone will now tell me that this is just the wrong forum for that. Point taken.

 

[Mendel]

This doesn't align with my memory of Chandler's careful analysis of the press conference. What context are you claiming is left out?

I don't know because there's no link to the source. That's not good. It's not transparent.

We don't know why Shyam Sunder said that, or if he subsequently qualified or clarified it. The context is simply missing.

 

[Mendel]

Interesting point. And there's a sense in which it is correct. In my view, conspiracy theorists and debunkers alike are excessively obsessed with "facts" that they think can settle the questions, though they of course disagree about what counts as "evidence".

Neither facts nor evidence are arbitrary. This is not simply a disagreement.
Truth is not a matter of opinion, like the fake news purveyors would have you believe.
The fact that you espouse these views disqualifies you as a skeptic.

But I'm ready to hear how you compose your reality, if it's not based on "evidence".

 

[Mendel]

What would that relationship be? Can you prove it?

Evaded.

What reasoning, exactly? Please be explicit.

Evaded.

It appears @Thomas B 's words have no meaning.

 

[Thomas B]

I don't know because there's no link to the source. That's not good. It's not transparent.

We don't know why Shyam Sunder said that, or if he subsequently qualified or clarified it. The context is simply missing.

Are we looking at the same page? They clearly refer back to the August 26, 2008 briefing.

Dr. Shyam Sunder explains the meaning of free fall at NIST’s WTC 7 Technical Briefing on August 26, 2008.

https://www.ae911truth.org/evidence/free-fall-acceleration

And then immediately refer us to Chandler's detailed video analysis of the briefing:
https://www.ae911truth.org/evidence/videos/video/7-nist-finally-admits-free-fall-part-1 (link fixed)

They also link to his essay, in which he provides the context in writing, also noting the response of John Gross:

I had an opportunity to confront NIST about the easily demonstrated fact of free fall at the technical briefing on August 26, 2008. I and several other scientists and engineers also filed official "requests for correction" in the days that followed. When they released their final report in November 2008, much to the surprise of the 9/11 Truth community, they had revised their measurements of the collapse of the building, including an admission of 2.25 seconds of absolute free fall. However, they couched the period of free fall in a framework of a supposed "three phase collapse sequence" that still occupies exactly 5.4 seconds.

The recurrence of 5.4 seconds, even in a completely revised analysis, is very puzzling until you realize its context. NIST lead investigator Shyam Sunder told the audience in the August 26, 2008 Technical Briefing that their computerized collapse model had predicted the collapse down to the 29th floor level would take 5.4 seconds, well beyond the 3.9 seconds required for free fall. From the events at the Technical Briefing it appears that a team headed by structural engineer John Gross dutifully fabricated a 5.4 second observation to exactly match the prediction. Anyone with any experience in laboratory measurement would have expected some amount of uncertainty between the prediction and the measurement. They would have been doing extremely well to come up with a computer model that would predict the collapse time within 10%. But no...their measurement exactly matched the prediction to the tenth of a second. Keep in mind that their computer model was constructed in the absence of the actual steel, which had long since been hauled away and destroyed. According to NIST's records, none of the steel from Building 7 remains. (Pause and ponder that fact for a moment. Anyone who has watched CSI knows the importance of preserving the physical evidence in a crime scene. Destroying a crime scene is in itself a crime, yet that is exactly what happened in the aftermath of 9/11, and it happened over the loud protests of the firefighters and others who had a stake in really finding out the truth.)

Back to our story. NIST's computer model predicted 5.4 seconds for the building to collapse down to the level of the 29th floor. John Gross and his team found the time the roofline reached the 29th floor, then picked a start time exactly 5.4 seconds earlier to give a measurement that matched the model to the nearest tenth of a second. They took their start time several seconds prior to the actual start of free fall when nothing was happening. The building was just sitting there, with the clock running, for several seconds. Then it dropped, with sudden onset, and continued for 2.5 seconds of absolute free fall.

https://www.ae911truth.org/evidence...911truth/101-free-fall-and-building-7-on-9-11

You're free to disagree with him, of course. But I don't think the charge that he (and therefore AE911T) is quoting NIST "out of context" can be made to stick.

 

[Mendel]

Are we looking at the same page?

Yes. It doesn't link to the briefing, or a transcript of it.

And your offtopic quote contains several falsehoods, as explained above.

 

[Thomas B]

But I'm ready to hear how you compose your reality, if it's not based on "evidence".

In part, one wants to refer to evidence; but, in part, one must defer to authority. Otherwise one is playing whack-a-mole with facts proffered by anonymous members of forums like this.

At the end of the day, I will not hold a view about 9/11 -- either in re its engineering or its historical aspects -- that isn't endorsed by some credible figure of authority. That doesn't have to be an "official" government agency, mind you. It just has to be someone (preferably several) whose credibility is actually on the line. Of course, where authorities disagree, I have to make a judgment call. But even that is an assessment of both the evidence and the authority involved.

 

[Oystein]

Thomas, you quote Chandler:

... When they released their final report in November 2008, much to the surprise of the 9/11 Truth community, they had revised their measurements of the collapse of the building, including an admission of 2.25 seconds of absolute free fall. ...

https://www.ae911truth.org/evidence...911truth/101-free-fall-and-building-7-on-9-11
Questions (I would not mind if @Mendel also tried to answer, and we compare answers then ):

1. Is the building ever in "2.25 seconds of absolute free fall" - YES or NO, Thomas?
2. Is the North wall ever in "2.25 seconds of absolute free fall" - YES or NO, Thomas?
3. Does NIST "admit" "2.25 seconds of absolute free fall" - YES or NO, Thomas?
4. Is Chandler correct - YES or NO, Thomas?
5. Is NIST correct - YES or NO, Thomas?

From my post #38, I have open questions:
Will you understand and will you admit that WTC7 was not at any time, not even during the short time interval when a point on the roofline was observed to move at about g, anywhere near freefall acceleration?

 

[Thomas B]

Yes. It doesn't link to the briefing, or a transcript of it.

This is very weird. It does link to AE911T's video of the briefing (contained in Chandler's analysis). And it makes specific reference to the name and date of a briefing that is then easily discoverable online. This is not good enough for you?

 

[Thomas B]

Will you understand and will you admit that WTC7 was not at any time, not even during the short time interval when a point on the roofline was observed to move at about g, anywhere near freefall acceleration?

I'm still thinking about those questions.

I was quoting here, not to endorse Chandler's views, but to show that he is not taking Sunder's remarks "out of context," as @Mendel claims.

 

[Thomas B]

Evaded.

Evaded.

It appears @Thomas B 's words have no meaning.

Are we really going to accuse each other of evading questions that we haven't answered within an hour of being asked?

Many of the issues you all raise here literally give me pause. Sometimes, I actually don't have an answer. Which means I have to think about it for days, even weeks and months. You seem very impatient for me to see the error of my ways. I'm sorry my mind doesn't work that way.

 

[Mendel]

Are we really going to accuse each other of evading questions that we haven't answered within an hour of being asked?

Many of the issues you all raise here literally give me pause. Sometimes, I actually don't have an answer. Which means I have to think about it for days, even weeks and months. You seem very impatient for me to see the error of my ways. I'm sorry my mind doesn't work that way.

This isn't about an issue I raised. (Well, it is, but I raised them in the OP, not an hour ago.)
This is about words you used. In a serious argument.
And it now turns out you do not know what you meant.
This is disrespectful to the people you're talking to.

I have not evaded any question.

 

[Mendel]

In part, one wants to refer to evidence; but, in part, one must defer to authority. Otherwise one is playing whack-a-mole with facts proffered by anonymous members of forums like this.

At the end of the day, I will not hold a view about 9/11 -- either in re its engineering or its historical aspects -- that isn't endorsed by some credible figure of authority. That doesn't have to be an "official" government agency, mind you. It just has to be someone (preferably several) whose credibility is actually on the line. Of course, where authorities disagree, I have to make a judgment call. But even that is an assessment of both the evidence and the authority involved.

Soo... suddenly the evidence does matter.

Would you say you'd be looking for "facts that you think can settle the questions" arising from the authorities' differences?

When you assess "authority", does it matter that neither Gage nor Chandler are engineers?

 

[Thomas B]

Me at 7:49

Here, I think the skeptic (and just the person who is curiously investigating these issues) is entitled to say that there is an important relationship between the acceleration of the collapse and the resistance the structure offered.

You at at 8:16

What would that relationship be? Can you prove it?

You at 9:25:

Evaded.

And, to put a button on it:

It appears @Thomas B 's words have no meaning.

I don't think I'm the one who's being disrespectful.

Is your point that, since you're right, my not immediately admitting that you are right is a sign of disrespect?
My view is that taking time to consider someone's points before responding is, at the very least, also a sign of respect.

 

[Mendel]

Is your point that, since you're right, my not immediately admitting that you are right is a sign of disrespect?
My view is that taking time to consider someone's points before responding is, at the very least, also a sign of respect.

You had answered my post, taking as little time as you yourself chose, but omitted to answer these questions.
It's fine to take time about new issues, but that was to clarify points you had made yourself.
If you don't know why you made them, the proper recourse is to retract the post.

 

[Thomas B]

You had answered my post, taking as little time as you yourself chose, but omitted to answer these questions.
It's fine to take time about new issues, but that was to clarify points you had made yourself.
If you don't know why you made them, the proper recourse is to retract the post.

I will keep that in mind in responding to you going forward. It will mean I won't respond as quickly, of course. Cheers.

 

[Thomas B]

that was to clarify points you had made yourself.
If you don't know why you made them, the proper recourse is to retract the post.

I haven't said I anything I feel I need to retract, though I may have course have said something that is wrong. Is there something you think I shouldn't even have considered posting? (I'm a little confused about what I've done to make you say that my "words have no meaning". I must have committed a pretty radical breach of logic or decorum.)

 

[Gamolon]

This doesn't align with my memory of Chandler's careful analysis of the press conference. What context are you claiming is left out?

Explain why Chandler’s graph, in his careful analysis, shows about 1 second of non-freefall when the roofline starts to descend? If all supports were immediately cut/removed, then why didn’t the roofline start free fall at the onset?

 

[Gamolon]

This doesn't align with my memory of Chandler's careful analysis of the press conference. What context are you claiming is left out?

What percentage of the WTC7, in Chandler’s careful analysis, do you think descended at free fall for 2 seconds?

 

[Thomas B]

Soo... suddenly the evidence does matter.

Would you say you'd be looking for "facts that you think can settle the questions" arising from the authorities' differences?

When you assess "authority", does it matter that neither Gage nor Chandler are engineers?

In a situation where Gage (an architect) and Chandler (a physics teacher) are saying that NIST (a government agency) is wrong, I tend to think that NIST is probably right, and that whatever errors they have committed would be pointed out by engineers in the scientific literature (people like Uwe Starossek). But that doesn't immediately solve the problem of understanding what the authorities I trust say. As I keep saying, my problem is not deciding what/who to believe; it is one of making sense of what they say.

Many of the things that people here seem to want me to believe about the WTC collapses are not, as far as I can tell, compatible with what recognized authorities on the subject say. So to believe them would be to live in a somewhat strange universe where we learn about these things in online forums, rather than in established scientific forums.

 

[Thomas B]

Explain why Chandler’s graph, in his careful analysis, shows about 1 second of non-freefall when the roofline starts to descend? If all supports were immediately cut/removed, then why didn’t the roofline start free fall at the onset?

I'm not sure I understand the question. Can you mark the point in the graph you're talking about?

But, in any case, my point wasn't that Chandler is right, nor do I know how to explain any anomalies in his presentation. My point was, against @Mendel's assertion to the contrary, that Chandler engaged with Sunder's point in its context in great detail.

 

[Gamolon]

I'm not sure I understand the question. Can you mark the point in the graph you're talking about?

But, in any case, my point wasn't that Chandler is right, nor do I know how to explain any anomalies in his presentation. My point was, against @Mendel's assertion to the contrary, that Chandler engaged with Sunder's point in its context in great detail.

We’ll make this easy.

Do you think WTC7 fell at free fall? Yes or no?

 

[econ41]

We’ll make this easy.

Do you think WTC7 fell at free fall? Yes or no?

I agree, discussing a topic would be more productive, even though it is not the thread topic.

But why start halfway into the argument?

Start from the beginning. Take it one step at a time and see who agrees.

Step #1 -Do we agree that both Chandler and NIST claim that a marked location at the roofline of WTC 7 fell with Free Fall acceleration, within the accuracy of their measuring methods?

There is no point debating if it was a state of Free Fall if we don't even agree on free-fall acceleration.

And there are about half a dozen more steps before we can understand why the physics principle of @Mendel's OP example is relevant.

Better still of course would be if members could agree as to what claim they are disputing. It makes it a damn sight easier to discuss if all parties agree what they are discussing.

 

[qed]

f) And here, we can apply what we learned in above experiments: The UPward acceleration of the core-side of the floor beams causes a DOWNward acceleration of their perimeter ends in addition to freefall, and that impulse is, IMO, what makes the perimeter accelerate, briefly, at >g!

Stop it! We have agreed not to talk of this bunk!

 

[qed]

This relates to bunk spread by members on this site and it makes me very angry. There is no evidence of over g collapse in 9-11, it is bunk we should not entertain.

This bunk keeps coming back like that old friend... I know where this goes from past experience on eventually locked threads.

 

[econ41]

This relates to bunk spread by members on this site and it makes me very angry. There is no evidence of over g collapse in 9-11, it is bunk we should not entertain.

Do you refer to over "G" as a phenomenon of physics or are you only denying it in the context of WTC 7?

 

[qed]

Do you refer to over "G" as a phenomenon of physics or are you only denying it in the context of WTC 7?

No evidence in WTC 7 context. We have been here before at least 4 times in the last 10 years. You cannot present it.

 

[Thomas B]

Do you think WTC7 fell at free fall? Yes or no?

I don't have an opinion on the technical issue that I think is in dispute here.

 

[qed]

This WTC7 over G bunk exists only on MetaBunk. It is even gone from 4Chan.

 

[Landru]

I don't have an opinion on the technical issue that I think is in dispute here.

Then why are you commenting?

 

[econ41]

No evidence in WTC 7 context.

Thanks.

You cannot present it.

It is not needed - the discussion is already circling. Without anyone showing any relevance of "over G" - the actual thread topic - to WTC 7 collapse.