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Questions about free fall speed and 9/11


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Initial post: Mar 4, 2013 7:53:12 AM PST
Last edited by the author on Mar 6, 2013 9:23:59 AM PST
anne says:
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In reply to an earlier post on Mar 4, 2013 8:10:21 AM PST
Last edited by the author on Mar 4, 2013 11:21:51 AM PST
J. Deen says:
Hi Anne,

I'm not a structural engineer, but I play one on the interwebs*.

Here is a link that could answer your question and others:

"This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h."
http://www.tms.org/pubs/journals/jom/0112/eagar/eagar-0112.html

*not really, that was a fib

Posted on Mar 4, 2013 8:25:33 AM PST
A. Caplan says:
The building wasn't in free fall. There was air resistance and the factor of each floor and other parts of the lower structure resisting movement until overcome by the force of the falling material.

In reply to an earlier post on Mar 4, 2013 8:36:51 AM PST
Last edited by the author on Mar 4, 2013 8:37:21 AM PST
anne says:
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In reply to an earlier post on Mar 4, 2013 8:53:43 AM PST
Last edited by the author on Mar 4, 2013 8:54:26 AM PST
J. Deen says:
Anne, I believe the figures in question are referring to how quickly the north and south towers feel, not the others. The day the figures are consistent with expectations of destruction due to the airplane crashes and subsequent structural failures. I can cite a much more academic and math-heavy paper that concludes the same thing.

There are many other articles available dealing with lack of evidence of controlled demolition. As for exactly what is meant by "within ten seconds, " you'll have to check out the article ; I'm away from the computer right now.

Posted on Mar 4, 2013 11:12:22 AM PST
Rev. Otter says:
i'd be willing to wager that no building has ever collapsed at "free fall" speed, controlled demolition or otherwise.

In reply to an earlier post on Mar 4, 2013 1:13:04 PM PST
J. Potter says:
No kidding, as even in a demolition, the building is still in its own way, between itself and the ground. Demolition weakens the structure and allows it to collapse ... it doesn't blow it apart, allowing it to fall like unimpeded rain drops.

In reply to an earlier post on Mar 4, 2013 2:46:07 PM PST
Doog37 says:
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Posted on Mar 4, 2013 3:08:42 PM PST
Last edited by the author on Mar 4, 2013 3:09:12 PM PST
Before you folks work too hard, please be aware that "anne" is not a real person. It's the sock puppet of a notorious anti-semite on these forums. Undoubted it's building up to an accusation that Jews and Israel are responsible for 9/11. Sometimes "anne" acts as a complete bot, responding with questions seemingly relevant but simply derived from the posts of others. In this sense the bot acts very much like the old "Eliza" fake psychotherapy program.

Posted on Mar 4, 2013 5:04:46 PM PST
Last edited by the author on Mar 4, 2013 9:26:41 PM PST
Re OP: We know exactly how and why the buildings collapsed as they did. "Controlled demolition" was not part of any of it.
Buildings 1 and 2 each collapsed releasing energy equivalent to that of the Hiroshima bomb. The resulting blast waves fatally weakened Building 7, and eventually it collapsed as well.

In reply to an earlier post on Mar 4, 2013 9:06:33 PM PST
impact was nothing
the buildings are very strong
it was the fire
and inferior coating of beams with asbestos (or maybe never done to save money)
heat weakens steel
then gives
and the floor collapses

In reply to an earlier post on Mar 4, 2013 9:07:20 PM PST
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In reply to an earlier post on Mar 5, 2013 5:31:14 AM PST
anne says:
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In reply to an earlier post on Mar 5, 2013 6:16:06 AM PST
Irish Lace says:
"Much ado is made over the fact that the World Trade Center towers didn't collapse at free fall speed, "

Which is, in and of itself, a nonsensical notion. The buildings weren't in "free fall," so why would they be expected to collapse at "free fall speed," regardless of how they were destroyed. (And there is not a shred of evidence that they were destroyed by controlled demolition. But I know that this isn't going to mean squat to any truther who is married to his/her conspiracy.)

In reply to an earlier post on Mar 5, 2013 6:17:54 AM PST
Irish Lace says:
Thanks for the heads up.

In reply to an earlier post on Mar 5, 2013 6:29:28 AM PST
anne says:
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In reply to an earlier post on Mar 5, 2013 6:30:14 AM PST
John McClain says:
Asbestos, thermite. So lies. Black helicopters.

Posted on Mar 5, 2013 7:05:27 AM PST
Last edited by the author on Mar 5, 2013 7:22:17 AM PST
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In reply to an earlier post on Mar 5, 2013 7:33:45 AM PST
Doog37 says:
Having lived/worked/went to school in the area, I can say I do not think anyone could legitimately get the amount of explosives (or even thermite) in to the towers AND properly set without being noticed. I don't think there was a conspiracy so much as I would have expected the top portion of one or both of the buildings to "lean over" a least a little bit. Granted since both buildings experienced similar impacts and had nearly identical collapases it is fair to reason that such consistancy merits no further questions, but it still doesn't change that one side of each building was weakened considerable before the fires took place.
So without further evidence (and lets face it there is nothing left to examine) we just need to accept what we were told as review of most conspiracies are easily debunked and other more elaborate plots while still possible woud require a level of coordination, access and know-how that seems to go above and beyond what is logical to beleive.

In reply to an earlier post on Mar 5, 2013 7:41:22 AM PST
Last edited by the author on Mar 5, 2013 7:42:16 AM PST
anne says:
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In reply to an earlier post on Mar 5, 2013 7:42:00 AM PST
Doog37 says:
Who blamed Saddam? Osama Bin Laden and Al Qaeda were blamed.
Bin Laden is well known as a being part of a billionaire family from Saudi Arabia, but was exiled in 1992.

Posted on Mar 5, 2013 8:28:57 AM PST
A. Caplan says:
REALITY CHECK
Each tower was struck by a >300,000 lb. incendiary bomb containing over 16,000 gallons of jet fuel. There was no need for any further explosive devices.

Posted on Mar 5, 2013 8:54:21 AM PST
Last edited by the author on Mar 5, 2013 9:42:54 AM PST
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In reply to an earlier post on Mar 5, 2013 8:58:09 AM PST
Last edited by the author on Mar 5, 2013 8:58:51 AM PST
J. Deen says:
Doogie, (Can I call you that?)

Good question about lateral movement. I've included a section below dealing with just that, taken from this page, which I highly recommend:
http://www.tms.org/pubs/journals/jom/0112/eagar/eagar-0112.html

It (the page) deals with the possibility of lateral movement (see below), how the unique structure of the towers affected the collapse, the misunderstood nature of the fire (not nearly as hot as people think), what that means (structural failure happens at lower temps than people think), etc. It really is an interesting read, IMO, and makes the collapse a lot more understandable.

"It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made... [...] there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down. "

In reply to an earlier post on Mar 5, 2013 9:02:58 AM PST
J. Deen says:
Here's an article dealing specifically with NIST's review of the collapse of building 7.

http://www.popularmechanics.com/technology/engineering/architecture/4278874

It doesn't mention fall rates at all, so I may still look for that when I can.
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Discussion in:  Science forum
Participants:  31
Total posts:  663
Initial post:  Mar 4, 2013
Latest post:  Aug 7, 2013

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