The Collapse Of WTC7: Why was it so fast?

[runlikell]

The official government report on the collapse of WTC building 7 (a 47 story skyscraper which also collasped on 9/11 as the 3rd of the day) reports that during the first few seconds of its collapse, that the building accelerated at freefall speed.

 

This is astonishing. How could this be possible without the use of controlled demolition techniques to use explosive energy to more the matter that sits at the bottom of and directly underneath the building out of the way so that it does not provide resistance when the upper part moves through its normal path? That is, normally we use explosives from top to bottom to acheive fast collapes that are close to freefall. But now it is claimed that the explosives are not necessary? Why bother with controlled demolitions at all from now on then?

 

The fact is that the investigation was illegitimate for several reasons, not the least of which was that there was a major conflict of interest between WTC security managers being close family members to government employees with authority over the investigation. It's no wonder they didn't even bother examining for evidence of explosives.

[swansont]

The official government report on the collapse of WTC building 7 (a 47 story skyscraper which also collasped on 9/11 as the 3rd of the day) reports that during the first few seconds of its collapse, that the building accelerated at freefall speed.

 

That's not what the report says, so this is all moot, right?

 

The observed descent time of the upper 18 stories of the north face of WTC 7 (the floors clearly visible in the video evidence) was 40 percent greater than the computed free fall time. A more detailed analysis of the descent of the north face found three stages: (1) a slow descent with acceleration less than that of gravity that corresponded to the buckling of the exterior columns at the lower floors, (2) a freefall descent over approximately eight stories at gravitational acceleration for approximately 2.25 s, and (3) a decreasing acceleration as the north face encountered resistance from the structure below.

 

bottom of p. 48. Emphasis added.

 

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=861610

[md65536]

[...]the building accelerated at freefall speed.

 

 

[...]

 

The fact is that the investigation was illegitimate for several reasons, not the least of which was that there was a major conflict of interest between WTC security managers being close family members to government employees with authority over the investigation. It's no wonder they didn't even bother examining for evidence of explosives.

 

The inner structure of the building fell before the outside. It is only the outside of the building that fell at free-fall speed as if it was completely unsupported.

 

There was no need to do a legitimate investigation, because the government-accepted answer was quite clear: Heat from an office fire knocked a "lynch pin" i-beam off its seat, and without that one support all the other supports were quickly and easily pulled off balance, just like a building made of plastic straws balanced on end and tied to each other with pieces of string might do.

[rigney]

The official government report on the collapse of WTC building 7 (a 47 story skyscraper which also collasped on 9/11 as the 3rd of the day) reports that during the first few seconds of its collapse, that the building accelerated at freefall speed.

 

This is astonishing. How could this be possible without the use of controlled demolition techniques to use explosive energy to more the matter that sits at the bottom of and directly underneath the building out of the way so that it does not provide resistance when the upper part moves through its normal path? That is, normally we use explosives from top to bottom to acheive fast collapes that are close to freefall. But now it is claimed that the explosives are not necessary? Why bother with controlled demolitions at all from now on then?

 

The fact is that the investigation was illegitimate for several reasons, not the least of which was that there was a major conflict of interest between WTC security managers being close family members to government employees with authority over the investigation. It's no wonder they didn't even bother examining for evidence of explosives.

"CONSPIRACY", is that your first or second major? Perhaps you would also like to question President Kennedys murder in Dallas? Edited January 2, 2012 by rigney

[md65536]

"CONSPIRACY", is that your first or second major? Perhaps you would also like to question President Kennedys murder in Dallas?

Though the question's not directed at me, "CONSPIRACY" is my first major. I propose we stick to discussing the collapse of WTC7 in this thread.

[rigney]

Though the question's not directed at me, "CONSPIRACY" is my first major. I propose we stick to discussing the collapse of WTC7 in this thread.

Ten years after literally hundreds of millions have been spent trying to determine what happened at the trade center, the best minds in the business are not skeptical.Have you ever witnessed the demolition of a building? Especially one that has been inspected and prepared, using explosives for its destruction? Even a two or three story building requires much engineering and people with years of experience in the trade to do the job with accuracy. It isn't a simple task. While we can't prevent maniacs from causing destruction, the least we can do is not give them comfort in believing our own nation would do such a clandestine and heinous thing as to comfort them for their efforts.

As I said earlier in the previous post, jump on the Kennedy assassination theories also. It still doesn't satisfied some folks even after 50 years. Who knows?

http://www.ehow.com/how_2059817_demolish-building.html

Edited January 2, 2012 by rigney

[Pantaz]

... It still doesn't satisfied some folks even after 50 years. ...

Some people aren't satisfied that the Earth orbits the Sun. Heck, some people aren't even satisfied that the Earth is round! Dissatisfaction doesn't alter the facts.

 

Physics trumps Belief every time.

[md65536]

Ten years after literally hundreds of millions have been spent trying to determine what happened at the trade center, the best minds in the business are not skeptical.Have you ever witnessed the demolition of a building? Especially one that has been inspected and prepared, using explosives for its destruction? Even a two or three story building requires much engineering and people with years of experience in the trade to do the job with accuracy. It isn't a simple task.

 

Are you arguing that it's very difficult to bring down a building like that?

 

Because the facts are:

1. The building did come down that day.

2. There was external damage to building and there was a fire that was left to burn.

 

If you're trying to answer a question like "how much explosives or explosives expertise is required for these two things to happen", and if your answer is anything more than "Very little to none at all", then there is a problem here.

While we can't prevent maniacs from causing destruction, the least we can do is not give them comfort in believing our own nation would do such a clandestine and heinous thing as to comfort them for their efforts.

As I said earlier in the previous post, jump on the Kennedy assassination theories also. It still doesn't satisfied some folks even after 50 years. Who knows?

Is it better to avoid questioning things in order to also avoid comforting "maniacs"? Is it better to falsely believe "only outsiders would do a thing like that"?

 

The Kennedy assassination is off topic and possibly setting up a strawman. I'm not saying that OP's post can't be argued against, but I am saying that "It's a conspiracy theory" isn't a good argument on its own.

 

 

 

Some people aren't satisfied that the Earth orbits the Sun. Heck, some people aren't even satisfied that the Earth is round! Dissatisfaction doesn't alter the facts.

 

Physics trumps Belief every time.

 

And there are some who are satisfied in "the facts" only to the degree that the evidence warrants it, and there are some who call that "physics".

Edited January 3, 2012 by md65536

[rigney]

Are you arguing that it's very difficult to bring down a building like that?

 

Because the facts are:

1. The building did come down that day.

2. There was external damage to building and there was a fire that was left to burn.

 

If you're trying to answer a question like "how much explosives or explosives expertise is required for these two things to happen", and if your answer is anything more than "Very little to none at all", then there is a problem here.

 

Is it better to avoid questioning things in order to also avoid comforting "maniacs"? Is it better to falsely believe "only outsiders would do a thing like that"?

 

The Kennedy assassination is off topic and possibly setting up a strawman. I'm not saying that OP's post can't be argued against, but I am saying that "It's a conspiracy theory" isn't a good argument on its own.

 

And there are some who are satisfied in "the facts" only to the degree that the evidence warrants it, and there are some who call that "physics".

After watching and listening for ten years to the rhetorical conspiracy theories of 9/11, I've had it. This link will show just how far we have drifted from any truth.

 

9/11 witch hunt

http://www.youtube.com/watch?feature=endscreen&v=ovXy_enhxG4&NR=1

[md65536]

After watching and listening for ten years to the rhetorical conspiracy theories of 9/11, I've had it. This link will show just how far we have drifted from any truth.

 

9/11 witch hunt

http://www.youtube.c...vXy_enhxG4&NR=1

 

Yes, it's sad. Information doesn't make sense to some people, and they invent their own explanations. Then other people associate all the alternatives together (and others like Fox News encourage this), so that now anyone who questions what happened on 9/11 is grouped with any other "conspiracy nut".

 

I've got into these 9/11 arguments before and I can't prove anything useful. The best that I think can be agreed on is:

- There is not enough information to fully explain every detail of that day (as should be expected), and there are some puzzling questions that still remain.

- There were choices made in the name of protecting the interests of people, over doing the most thorough investigation possible. (Eg. supposedly avoiding comforting the enemy at the expense of the comfort of the families of victims).

 

So I don't think there's enough evidence to support the conspiracy theories, but I don't think there's enough evidence to disprove them all either. Scientifically, some open questions remain. I suppose it is a cold case.

[runlikell]

is it possible for an object to begin decent, and during a measured period to accelerate at free-fall speed, while simultaneously during this period moving downward through a pathway that is occupied by considerable mass? ie, a pool ball landing on another without losing momentum?

 

I am trying to comprehend NIST's explanation for the collapse of WTC7 as occurring without the aid of any added forces. Please do not resort to ad hominen attacks. Is this not a matter of basic physics? Because if I understand the agreed upon measurements of the first several stories of collapse of that building, as equal to free-fall acceleration, wouldn't that mean that had I jumped off the building at the moment the collapse began, and videotaped my twin standing on the edge of roof, that we would have both remained at the same elevation, even though I had nothing but air beneath me, yet my twin had a vertical wall of construction material directly beneath him?

 

Am I wrong to see this specific part of the collapse as a issue of basic physics? If incorrect, why? If it is indeed basic physics, can anyone give other examples of such a phenomenon occurring, especially ones which have occurred in the laboratory and can be repeated?

 

Thanks fellow critical thinkers and science lovers

Edited March 22, 2012 by runlikell

[swansont]

!

Moderator Note

Merged, since this is the same basic question. Don't open new threads on this.

As pointed out above, your premise is false. The initial collapse was not under free-fall conditions.

[runlikell]

What are playing word games now? Or are you seriously asserting that the outer building structure as observed through numerous video recordings, did no decent at freefall acceleration for any period of its collapse?

 

This is what it has come down to, huh? Deliberate misinterpretation. And hey, if you're not deliberately being mischievous then a pity your pathetic effort to respond to what I had intended to be addressed. It doesn't take an Enlgish scholar to figure out what I meant. Either start thinking more than a half dozen seconds or quit being an argumentitive bully.

 

Are we all at a consensus now that there is no such phenomenon that allows for freefall descent while passing through a fall line that contains substantial matter?

[Pantaz]

What are playing word games now? Or are you seriously asserting that the outer building structure as observed through numerous video recordings, did no decent at freefall acceleration for any period of its collapse?

If you are responding to swansont's last post, he referred specifically to the "initial collapse" described in the NIST report. As previously posted, the NIST report states that a 2.25 second period of free fall occurred between two periods of "acceleration less than that of gravity":

 

The analyses of the video (both the estimation of the instant the roofline began to descend and the calculated velocity and acceleration of a point on the roofline) revealed three distinct stages characterizing the 5.4 seconds of collapse:

• Stage 1 (0 to 1.75 seconds): acceleration less than that of gravity (i.e., slower than free fall).
  
• Stage 2 (1.75 to 4.0 seconds): gravitational acceleration (free fall)
  
• Stage 3 (4.0 to 5.4 seconds): decreased acceleration, again less than that of gravity
  

- Section 11, FAQs - NIST WTC 7 Investigation

 

 

is it possible for an object to begin decent, and during a measured period to accelerate at free-fall speed, while simultaneously during this period moving downward through a pathway that is occupied by considerable mass? ie, a pool ball landing on another without losing momentum? ...

 

When you added "simultaneously" you have indeed proffered a false premise. The report specifically states the measured free fall occurred prior to contacting additional material. Certainly, some portions of nearly any collapsing structure will experience brief periods of "free fall" between the instances of contacting/impacting neighboring debris.

 

 

... Because if I understand the agreed upon measurements of the first several stories of collapse of that building, as equal to free-fall acceleration, wouldn't that mean that had I jumped off the building at the moment the collapse began, and videotaped my twin standing on the edge of roof, that we would have both remained at the same elevation, even though I had nothing but air beneath me, yet my twin had a vertical wall of construction material directly beneath him? Am I wrong to see this specific part of the collapse as a issue of basic physics? If incorrect, why?

 

The initial 1.75 seconds were determined to be less than gravitational acceleration. Per your analogy, you would fall 15 meters before your twin achieved "free fall". Bear in mind, at that 1.75 second mark, you have reached a velocity of 17.15 meters per second (and continuing to accelerate), but your twin has been accelerating more slowly, so he has fallen a lesser distance and is traveling at something less than 17 m/s. Your velocity will never match that of your twin at any given time after zero.

 

As a (very rough) example, let's imagine that your twin's initial acceleration is 8 m/s^2 (free fall being 9.8 m/s^2). At 1.75 seconds, he has fallen only 12.25 meters (2.75 meters less than you) and is traveling at only 14 meters per second.

 

(Note: I understand that the initial 1.75 seconds is a period of increasing acceleration for the twin, so the velocity and distance traveled will be somewhat greater than my example, but I don't know how to do the calculations.)

[swansont]

What are playing word games now? Or are you seriously asserting that the outer building structure as observed through numerous video recordings, did no decent at freefall acceleration for any period of its collapse?

 

This is what it has come down to, huh? Deliberate misinterpretation. And hey, if you're not deliberately being mischievous then a pity your pathetic effort to respond to what I had intended to be addressed. It doesn't take an Enlgish scholar to figure out what I meant. Either start thinking more than a half dozen seconds or quit being an argumentitive bully.

 

Not deliberate misinterpretation. I merely assumed that you meant what you said: "first few seconds of its collapse" and "the first several stories of collapse". The NIST report is quite clear that these were not under free-fall conditions. Your claim to the contrary is false.

 

You really shouldn't be blaming me for your difficulties in constructing an argument.

[runlikell]

I am referring to the first few seconds of decent for the outer layer of the structure. We do all agree that the upper portion of the outer layer fell at free fall for a period of several seconds, right?

[Aemilius]

runlikell "This is astonishing. How could this (free fall) be possible without the use of controlled demolition techniques...."

 

It's not possible. In spite of all the drivel here to the contrary, no natural progressive structural failure or collapse (except for bridges and other structures that pass through air) could have created the conditions required for gravitational acceleration to have occurred at any point during the collapse of the building.

Edited February 21, 2014 by Aemilius

[Ophiolite]

I've never felt that hysteria was a good companion for an effective argument.

[Aemilius]

Right. I haven't seen an effective argument yet.... Do you have an effective argument?

 

Interesting that my opening remark, firmly based on well known physical principles, immediately gets a "Neg Rep" in a science forum!

Edited February 22, 2014 by Aemilius

[Ringer]

Right. I haven't seen an effective argument yet

 

Did you not see the argument that starting from a false premise usually leads to false conclusions? It's pretty effective and, as an added bonus, it's true!

[Aemilius]

You mean this?

 

Pantaz "When you added "simultaneously" you have indeed proffered a false premise. The report specifically states the measured free fall occurred prior to contacting additional material. Certainly, some portions of nearly any collapsing structure will experience brief periods of "free fall" between the instances of contacting/impacting neighboring debris."

 

That's semantics, not an effective argument. Maybe we should define what we're arguing about before we argue about it. This is a schematic representation of gravitational acceleration....

 

So, free fall only occurs when an object falls un-obstructed under the influence of gravity alone. If there's anything beneath the falling object that would tend to impede it's downward progress, then some of its gravitational potential energy will be used in overcoming the resistance and it will not be found falling at gravitational acceleration compared to an identical object falling un-obstructed from the same height at the same time over the same distance....

 

Control on the right, details....

http://picasion.com/pic76/ef2992a1bed34a1ad9d2e8f520c5ad7e.gif

The idealised object, or Control (above right), depicted in the animation is for comparison as a constant reminder of what happens to an object in free fall. The scenario (above left) in the animation is depicted on the left."

Edited February 22, 2014 by Aemilius

[Ringer]

Is that schematic your argument? Also, I don't think using the imperial system for physics problems is reasonable by any stretch of the imagination. . .

[Aemilius]

No, the schematic isn't an argument, it just illustrates free fall. How could a schematic be an argument? I'm just curious really, I don't have an argument/theory per se.... and the imperial system was good enough for the NIST to use in it's analysis and final report.

 

So what's your opinion of the whole thing Ringer? Do you agree with the NIST that the failure of one column caused/triggered the global collapse?

Edited February 22, 2014 by Aemilius

[Ophiolite]

I said:

I've never felt that hysteria was a good companion for an effective argument.

 

 

Then,

 

Right. I haven't seen an effective argument yet.... Do you have an effective argument?

 

I do not have an effective argument. (I do not have a formed opinion on the matter.) I do have an agenda.

 

This is my agenda. I favour remaining calm when presenting hypotheses, or viewpoints that are known to be controversial. Regardless of my view of these individual hypotheses, or viewpoints, it is my carefully considered opinion (supported by abundant research, personal experience and anecdotal evidence) that the proposer of these has a much better chance of persuading their audience if they eliminate negative emotions from their posts.

 

As someone convinced by the ability of the scientific method to develop better understanding of nature and of events, I dislike seeing arguments discarded automatically because their proposer has become emotional. Let the argument stand or fall on its own merits, not on the accompanying angst.

 

My agenda is to encourage posters who feel passionately about what may be a minority view to present that view in as neutral an emotional manner as possible.

 

To that end, I have offered you, in my one line post you commented on, some implicit advice. You are free to explicitly reject it.

[swansont]

You mean this?

 

Pantaz "When you added "simultaneously" you have indeed proffered a false premise. The report specifically states the measured free fall occurred prior to contacting additional material. Certainly, some portions of nearly any collapsing structure will experience brief periods of "free fall" between the instances of contacting/impacting neighboring debris."

 

That's semantics, not an effective argument.

 

Actually it's physics, and it's the same argument you make: that you don't get free-fall if you are colliding with material, but you will get free-fall if you don't.

 

What I would consider an effective argument is evidence that there were collisions that should have impeded free-fall. What it sounds like to me is that the argument is that one floor will not fall at g because it will contact the floor below it, but nobody appears to be claiming that the collapse happened that way.