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If the twin towers were left burning, could they soon collapsed?

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posted on Jul, 31 2006 @ 09:52 AM
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Originally posted by dubiousone
The time of 9.2 seconds is based on free-fall in a vacuum. Remember, Manhattan is at sea level on earth, not in outer space, though some might disagree on the latter point. Taking into account the air resistance at sea level, it appears that the towers indeed fell at near free-fall speed. There's a straightforward discussion of the issue at 911blimp.net...


There would be absolutely no problem with your statement, if it weren't for the fact...

it's completely wrong.

Please see the freefall velocity and drag calculations below. I have checked them and re-checked them and cannot find any error at this point, but will be glad to provide any and all equations and my methodology to any one who wants to review this.

This first one is freefall in a vacuum. Please note the column with the heading "form drag" is set to zero at all points. If we raised the collapse point of WTC 1 (the 94th floor here) to the top of the building, it would take 9.2 seconds for it to fall to the ground. (I have this bold red.) In actuality, the 94th floor would take 9 seconds because it wasn't this high.




Introducing pressure drag (but neglecting skin drag because it will be orders of magnitude less than the dominating pressure or "form" drag) and applying a 1.25 coefficient of drag for a flat plate orthogonal to the airflow, we get 10th of one second increase in the time it would take the 94th floor to fall to the ground (if it were raised to the top of the building).




And just in case some one wants to argue the coefficient of drag I selected, I went ahead and ran the same scenario with a coefficient of 2.0 (which is equivalent to a "square cylinder" orthogonal to the airflow). It added a second 1/10th of a second to the time for the 94th floor to fall to the ground from the top height of 1350-1360 feet.



Since the WTC 1 took 16 seconds to fall, we still have 6.6 seconds (with the Cd of 2.0) to account for - this accounting comes in the energy lost to destroy the floors.

I will be glad to incorporate any "finesses" anybody wants included in this (as long as there is actually a sound physical reason for doing so). I have the spreadsheet saved, so we can complicate this ad nauseum.

No...WTC 1 and WTC 2 did not fall "at near free-fall speed".

[edit on 7-31-2006 by Valhall]




posted on Jul, 31 2006 @ 10:01 AM
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Originally posted by Slap Nuts
I believe her middle ground... while totally over simplified "start stop every ten floors" makes a basic case for the length of time the pancaking would take to occur. Some of the momentum is conserved BUT much KE is lost in order to "break" the resistance of the undamaged structure.

What you're saying here is that the figure arrived at by incorrect method A should probably be roughly the same as what you think the figure arrived at by correct method B would be, so method A is therefore valid.


1. Kenetic energy is required to start the next floor moving because it is intact.
2. Not all of the momentum will be conserved because of the lost KE in #1.
3. This should have slowed the descent considerably from what we observed.
4. The only energy available at the onset was G.


I agree with all of the above (except the energy available was the PE), but none of those factors you mention are present in her hypotheticals in any way. A work-energy assessment similar to what Hoffman or even Ross did would be more appropriate for these. The only thing she's using is acceleration due to gravity and erroneous collapse times, combined with completely irrelevant models, so the times arrived at are meaningless numbers she might as well have pulled out of a hat. I'm not trying to bash her, and being a Prof of Mechanical Engineering she is much more qualified to comment on the issue than I, but red herrings such as this paper end up simply confusing the issue when people cite 8-10s as the actual collapse time and 100s as what the pancake collapse time should have been.

Anyway I think we're getting off track here. My bad, I believe.







[edit on 2006-7-31 by wecomeinpeace]



posted on Jul, 31 2006 @ 11:56 AM
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Originally posted by wecomeinpeace
What you're saying here is that the figure arrived at by incorrect method A should probably be roughly the same as what you think the figure arrived at by correct method B would be, so method A is therefore valid.


That is not what I meant. In A, she basiclly indicates that ALL of the momentum would be stopped at every floor... In B it does not stop at all in 9 floors... then stops at 10... this kind of averages out the conservation of momentum across 10 floors. At least in my head.



Originally posted by wecomeinpeace
I agree with all of the above (except the energy available was the PE)


Agreed... I should have said force.

OK.... back to the topic.



posted on Jul, 31 2006 @ 12:09 PM
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Originally posted by Slap Nuts

That is not what I meant. In A, she basiclly indicates that ALL of the momentum would be stopped at every floor... In B it does not stop at all in 9 floors... then stops at 10... this kind of averages out the conservation of momentum across 10 floors. At least in my head.




Okay, well then she would be wrong unless she can prove that at impact there is sufficient strength to endure the impact of the top of the building and "stop it from accelerating". Because the momentum is not going to go away unless the top hits a "wall" that is of sufficient strength to take the static and dynamic loading at impact. Apparently the lower floors weren't of that sufficient strength. But that is the question, now isn't it?

If the top of the building is still accelerating, the force upward at a floor impact would cause a negative JERK (derivative of acceleration). She is stating that with every floor collision some of the velocity is taken away, but she doesn't take into account that the velocity taken away is coming from an accelerating object.

EDIT: reworded, didn't read right.


[edit on 7-31-2006 by Valhall]



posted on Jul, 31 2006 @ 02:21 PM
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Originally posted by Skadi_the_Evil_Elf

No, my opinion has not changed. When I used the term freefall, I was using the 14 second figure. Val came up with 16 seconds for another tower. So technically, it wasn't "free fall" in the most literal sense.


Skadi...there is only one speed for freefall, and that is due to gravity alone...


Originally posted by Skadi_the_Evil_Elf
But it was still entirely too fast given the building and circumstances. Please read my later posts for details of my view on this.


Sorry, but watching some buildings being demolished in your spare time does not make you an expert. you can have your own opinion if you want but it is still wrong.


Originally posted by Skadi_the_Evil_Elf
Absolutely not. Again, they fell at pretty much near a freefall speed. They fell entirely too fast. It looked like freefall speed to me, even though freefall is much lower speed. Read my later posts for my clarification of this.


1/3 the speed of freefall, or gravity, is nowhere near the buildings falling at freefall. What I see here is like with so many other people, when you are presented with evidence that disproves such claims, you still deny the facts.


Originally posted by Skadi_the_Evil_Elf
Like I said, I am yet to hear a credible answer as to why building 7 collapsed. The offical story is, well.........unbelievable. Many more buildings should have collapsed on their own if this was the case.


Nope, not all of them were as high as WTC7, which did play a part in the collapse, not all of them were hit with debri from the Twin towers which took part of wtc7, and WTC5 which was in between one of the twin towers and WTC7 was also demolished, the debri from that building also hit WTC7. If i remember correctly there were some other buildings that also collapsed but just because some collapsed doesn't mean "they all had to collapse".



posted on Jul, 31 2006 @ 02:36 PM
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Originally posted by Muaddib
Skadi...there is only one speed for freefall, and that is due to gravity alone..


And there are speeds quite near it too. Given the factors of the day and everything that happened, it is reasonable to assume perfect freefall was not likely. But close to it. Factoring everything else in.


Sorry, but watching some buildings being demolished in your spare time does not make you an expert. you can have your own opinion if you want but it is still wrong.


Of course Im not an expert. Did I say that? But observation is the first tool of any logical exercise. I do not need an expert to tell me what already looks mighty suspicious. And Im not the only person around who thinks so.

Not believing the offical fairy tale does not make me wrong, since the offical fairy tale has yet to be proven either. For now, everyone is in the realm of theory.


1/3 the speed of freefall, or gravity, is nowhere near the buildings falling at freefall. What I see here is like with so many other people, when you are presented with evidence that disproves such claims, you still deny the facts.


I have denied no facts. 1/3 the speed may sound a big number. but we are talking about mere seconds and thousands of tons of concrete, steel, and resistance factored in.



Nope, not all of them were as high as WTC7, which did play a part in the collapse, not all of them were hit with debri from the Twin towers which took part of wtc7, and WTC5 which was in between one of the twin towers and WTC7 was also demolished, the debri from that building also hit WTC7. If i remember correctly there were some other buildings that also collapsed but just because some collapsed doesn't mean "they all had to collapse".


If that were the case, there should have been an epidemic of collapsing buildings around the WTC. But there wasnt. Some buiuldings deemed to damaged by the crashes and collapses were later demolished. But none collapsed. Building 7 did.

And there were a number of high rises in the vicinity, some close to the size of WTC 7.



posted on Jul, 31 2006 @ 03:08 PM
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Originally posted by Muaddib
BTW, VAlhall, if there was only 250 C temperature at the WTC from the fires, how is that possible when temperatures in a residential fire often reach 500 C to 650 C?

So how come the fires at the WTC were less than those in a residential fire?


[edit on 30-7-2006 by Muaddib]


I'll answer this one. A residential fire can often reach 500 to 650 C. That is the fire....NOT the structural steel involved in those fires. Steel is a heat sink and will wick the heat away from the source. NIST even states that none of the steel they tested reached over 250 C.



posted on Jul, 31 2006 @ 03:30 PM
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I think the NIST testing targeted the mid range temps and the 250C in no way is meant to be thought of as the highest temps the steel reached in the fires.



posted on Jul, 31 2006 @ 03:58 PM
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Originally posted by Griff
Steel is a heat sink and will wick the heat away from the source.


Which particular pieces of steel are you referring to?

The floor trusses?

They were rather thin.

fire-research.group.shef.ac.uk...



posted on Jul, 31 2006 @ 04:14 PM
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Originally posted by HowardRoark
Which particular pieces of steel are you referring to?

The floor trusses?

They were rather thin.

fire-research.group.shef.ac.uk...




No, I'm not talking about floor trusses. I believe as does Valhall that once initiation started that the "pancaking" could have happened. There is alot of dynamic force applied to everything that was not designed for. It's initiating it that gets me. Also, none of the floor trusses would fail at the same time. That means that you didn't have a floor crashing down on another at full force...until the columns gave way and global collapse started.

I think my scenario still stands. That is, taking out the core columns by some means to initiate floor trusses to sag/rendering the designed 50% gravity load resistance gone/rendering the lateral support of the exterior columns null. Anyway, I'm getting off the subject of the question asked of me.



posted on Jul, 31 2006 @ 04:32 PM
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taking out the core columns by some means to initiate floor trusses to sag/rendering the designed 50% gravity load resistance gone/rendering the lateral support of the exterior columns null.


But wouldn't that scenerio pull in on the outer columns in a very general way if the trusses were still connected to the core causing obvious distorting of the outer face of the building?



posted on Jul, 31 2006 @ 06:24 PM
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Originally posted by Vushta


But wouldn't that scenerio pull in on the outer columns in a very general way if the trusses were still connected to the core causing obvious distorting of the outer face of the building?


I believe they did just that, didn't they?



posted on Jul, 31 2006 @ 06:38 PM
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Originally posted by Valhall

Originally posted by Vushta


But wouldn't that scenerio pull in on the outer columns in a very general way if the trusses were still connected to the core causing obvious distorting of the outer face of the building?


I believe they did just that, didn't they?




On a couple of floors over a period of time as far as I know. At least thats what the pictures show.

I was refering to the sudden 'removal' of the core via a series of rapid explosions. If it suddenly dropped it would seem that there should have been visual evidence of a sort of accordian effect all around the towers. But the way it looks to me the forces were basically isolated around the leading head of the collapse.



posted on Jul, 31 2006 @ 06:47 PM
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Originally posted by Vushta


On a couple of floors over a period of time as far as I know. At least thats what the pictures show.

I was refering to the sudden 'removal' of the core via a series of rapid explosions. If it suddenly dropped it would seem that there should have been visual evidence of a sort of accordian effect all around the towers. But the way it looks to me the forces were basically isolated around the leading head of the collapse.


I understand what you're saying now, and kind of agree, and kind of don't.

The floor truss connections were failed at the outer perimeter in a downward motion (and that's for almost all the specimens they looked at), while the truss connections on the core columns were not (and that's for almost all the specimens they looked at). To me this is indicative of the core columns failing and bringing the floor trusses down with them. The part I don't agree with is equating the core column failures to "taking out the core columns"...they're still there, they're just falling now and dragging down everything.

What I want explained to me is how the opposite wall of WTC 2 - which was in severe tension at the time the top was listing approximately 20 degrees from vertical, suddenly failed in compression to the point it righted the top of the tower?

That's the one I keep hanging in this thread for - an explanation I can buy on that one.



posted on Jul, 31 2006 @ 07:08 PM
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Originally posted by Valhall

I understand what you're saying now, and kind of agree, and kind of don't.

The floor truss connections were failed at the outer perimeter in a downward motion (and that's for almost all the specimens they looked at), while the truss connections on the core columns were not (and that's for almost all the specimens they looked at). To me this is indicative of the core columns failing and bringing the floor trusses down with them. The part I don't agree with is equating the core column failures to "taking out the core columns"...they're still there, they're just falling now and dragging down everything.

What I want explained to me is how the opposite wall of WTC 2 - which was in severe tension at the time the top was listing approximately 20 degrees from vertical, suddenly failed in compression to the point it righted the top of the tower?

That's the one I keep hanging in this thread for - an explanation I can buy on that one.


Could part of it be that once the connections at the perimeter failed it released the forces acting on the core connections and that may be part of why they didn't fail in a sort of downward shear?

Are there any videos or stills that you know of that show what was going on at the other wall as the top was listing 20 degrees? It seems like the potential variable that could have been interacting in that kind of chaos may product some hard to understand effects. With most of the inside area being open space and the possibility of an unimpeded drop for instance on one side while the other side was incountering resistance...well who knows what it might look like.
Just a stab in the dark.



posted on Jul, 31 2006 @ 08:18 PM
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M.I.T. research essays here guy's ! Whew is that alot of reading. Y'all sure are good at math. Lot's O' this stuff way over my head, here, but I'm learning. From what I see here they buy the Gov. line. They are independent , in the sense they aren't USG ! If ya ain't seen this yet,check it out ! Happy Hunting!


The downloadable full report contains eight articles that deal with the September 11, 2001 World Trade Center (WTC) disaster and its consequences, written by researchers at the Massachusetts Institute of Technology. For the most part, these articles were prepared between September 2001 and February 2002, and were revised in part in the spring of 2002.[/e]

web.mit.edu...



posted on Jul, 31 2006 @ 09:35 PM
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Originally posted by Valhall

What I want explained to me is how the opposite wall of WTC 2 - which was in severe tension at the time the top was listing approximately 20 degrees from vertical, suddenly failed in compression to the point it righted the top of the tower?

That's the one I keep hanging in this thread for - an explanation I can buy on that one.


IMO, it depends on where the fulcrum was. If it was the core, then my scenario would work I believe. If you think about the fulcrum being the core, then severing the core would collapse the cap on the rest of the building and thus cause compression on the opposite side as the cap had no support at that point from the core and failed straight down instead of continuing with the tilt. Would this make sense Valhall? Like I said before, you're the dynamics person here....I'm just statics.

If the fulcrum was the facade columns, then I have no idea.

BTW Vushta, I think the reason you are having trouble with my scenario is that you are hung up on explosives. I believe no explosives were needed. But that's just my opinion and could be wrong and if anyone wants to, feel free to contradict me.



posted on Jul, 31 2006 @ 09:36 PM
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Originally posted by Duhh
M.I.T. research essays here guy's ! Whew is that alot of reading. Y'all sure are good at math. Lot's O' this stuff way over my head, here, but I'm learning. From what I see here they buy the Gov. line. They are independent , in the sense they aren't USG ! If ya ain't seen this yet,check it out ! Happy Hunting!


The downloadable full report contains eight articles that deal with the September 11, 2001 World Trade Center (WTC) disaster and its consequences, written by researchers at the Massachusetts Institute of Technology. For the most part, these articles were prepared between September 2001 and February 2002, and were revised in part in the spring of 2002.[/e]

web.mit.edu...


Other than misplaced sarcasm, I can't see what your point is here. You're linking us to a 4 year old report that had no insight into the data being analyzed by the NIST.

You want to elaborate in a constructive manner, rather than acting like you don't have a clue what you're talking about?

[edit on 7-31-2006 by Valhall]



posted on Jul, 31 2006 @ 09:41 PM
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What is with all the anger here? This is not surgery ! You are not the only people here. The info was posted for those who haven't read it . I was not aware this was your PRIVATE thread here. Geeze have a time-out , or something.

[edit on 31-7-2006 by Duhh]



posted on Jul, 31 2006 @ 09:44 PM
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Originally posted by Duhh
What is with all the anger here? This is not surgery ! You are not the only people here. The info was posted for those who haven't . Geeze have a time-out , or something.


No anger. Where did you pick that up at? I asked a question...what is your point? Can you answer that? What is the point of the link to the 4-year old suppositional essays?



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