Modeling the WTC collapses

There was another thread posted in GD, "Did Bush Lie on 9/11?" here:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=132&topic_id=1598983&mesg_id=1604586

In one of the subthreads, SoCalifer posits a formula that could be used to define the expect rate of collapse....and compares it to the actual time:

"-- According to the law of falling bodies as originally put forward by Galileo Galilei, and excepted by science up to today is: The total distance traveled at the end of any specific time in a total vacuum is calculated by this formula: Distance (D) = (32.16/2) X Time In Seconds Squared. And if there is ANY resistance, then the speed and the time of the falling body slows down in relation to the resistance.

In the case of the WTC towers we know that they were 1,350 feet tall. Thus you have this equation for the absolute fastest time these two towers could free fall in a vacuum: 1350 = (32.16/2) X Time In Seconds Squared. This works out to 9.16 seconds.

However, the south tower came down in 10.4 seconds (just one second slower than free fall in a vacuum) despite all the resistance put up by all the 250 major interior and exterior steel columns in that fall. --And-- Even more unusual is that the north tower came down in 8.1 seconds."

---------------------------------

Now, I'm not sure if this is the correct formula to describe the collapsing tower, but it leads to an intriguing test between the "explosives" scenario and the "natural" scenario. Has any engineering study been done by computer modeling/finite analysis of the WTC's that test the 2 scenario's? Obviously, there are an almost infinite set of variables that affect the collapse rate. A crude model would have to include 1000's of these variables and allow the event to run 1000's of times to come up with some expected nominal time value, based on the structural assumptions, post-crash, for each tower. The model could also be constructed to tests various explosion scenarios and the resultant collapse time for each, too.

Seems to me that we could then conclude which model ("natural" or explosives") best fits the actual collapse time of both events.

Comments?

Although they don't (as far as I can tell) test the "controlled demolition" theory, I can list the characteristics of their models for reference. From the October 2004 Update:

Analysis of Probable Collapse Sequence Analysis of Probable Collapse Sequence

NIST simulated highly- complex structural failures and fires at the component, subsystem, and system levels to determine the probable collapse sequences. In many instances, NIST tested the limits of current engineering software and computational platforms. The computational models developed by NIST include:
• A detailed structural model of a typical truss- framed floor of the WTC towers with over 40,000 elements and 166,000 degrees of freedom.
• A detailed structural model of a typical beam- framed floor of WTC towers with over 12,000 elements and 35,000 degrees of freedom.
• A detailed global model of WTC 1 structure with over 80,000 elements and 218,000 degrees of freedom (with 17 flexible and other rigid diaphragm floors).
• A similar detailed global model of WTC 2 structure with over 78,000 elements and 200,000 degrees of freedom.
• A structural model of a typical turbofan engine of the Boeing 767-200ER aircraft with over 60,000 elements and 100,000 nodes.
• A comprehensive structural model of the Boeing 767- 200ER aircraft, including engines, airframe, landing gear, fuel tanks, passenger cabin, and cargo bay, with over 530,000 elements and 740,000 nodes.
• A computational fluid dynamics model of the fires and thermal environments that encompasses 8 floors and 1,200,000 cells in WTC 1 and 6 floors and 900,000 cells in WTC 2.
• A fire- structure interface model that maps the thermal environment onto and within the structural model, comprising 500,000 floor elements and 300,000 column nodes per building floor.

The first four models described above were used to evaluate the baseline performance of the WTC towers under design gravity and wind loads. They also served as reference models for analyses of aircraft impact damage and response of the thermally- insulated WTC structures to subsequent fires.
</quote>


As far as what software was used, the aircraft impact damage was modelled using LS-DYNA and the thermal analysis and structural response and failure analysis were modelled using ANSYS 8.0.

There were two previous studies done: one by MIT and one by Silverstein Associates (for insurance purposes). I don't have copies of those.

would universities have access to it? Seems that it would have a lot of value for teaching structural engineering theory.

My gut tells me that the total time of the collapse event would be significantly different between a collapse that starts 80 floors up and one that uses explosives to disintegrate the base.....and each could be compared to the actual time recorded.

There are public domain FEA/CFD programs, but ANSYS is not one. Neither is the source material for the meshes used - Boeing owns the one for the aircraft for example.

Some universities will have licenses available for student use. We have an ANSYS class here at the UofA, but the lab containing the computers with ANSYS loaded is only available to students in the class.

List of FEA software

List of Dynamic Simulation software

You might be able to test out some general theories using these programs, but I doubt you'll be able to go as in-depth as the NIST study. Anyway, good luck and if you try it keep us posted on your results! :)

My son is showing interest in mechanical engineering, so I've bookmarked for downloading. Who knows? Maybe I can get the answers from him in 3 or 4 years...

If he does go into ME he should have access to the "big name" software: ProEngineer, ANSYS, etc. His school should have licenses for some of those programs, and I recommend he take at least one good CAD class - it's pretty much universal in industry, although there are different ones used in various areas. CATIA, for example, is almost exclusive to the aerospace industry.

these days. It's amazing how that software has shrunk time from design to production.

He's playing around with CAD-Lite now, a 2-D drawing tool. He's optimizing his room layout now. :-) I'm just glad to see his interest moving away from Nintendo into something useful....finally.

"-- According to the law of falling bodies as originally put forward by Galileo Galilei, and excepted by science up to today is: The total distance traveled at the end of any specific time in a total vacuum is calculated by this formula: Distance (D) = (32.16/2) X Time In Seconds Squared. And if there is ANY resistance, then the speed and the time of the falling body slows down in relation to the resistance.

In the case of the WTC towers we know that they were 1,350 feet tall. Thus you have this equation for the absolute fastest time these two towers could free fall in a vacuum: 1350 = (32.16/2) X Time In Seconds Squared. This works out to 9.16 seconds.

However, the south tower came down in 10.4 seconds (just one second slower than free fall in a vacuum) despite all the resistance put up by all the 250 major interior and exterior steel columns in that fall. --And-- Even more unusual is that the north tower came down in 8.1 seconds.

Thus if we are to believe the government's official story as to why the towers fell, then we are to believe something that defies the laws of gravity! However if we understand that demolition charges were used to "pull" the towers down, then we would not be believing in something that defies gravity." - SoCalifer



Let's say, for the sake of argument, that there were explosives in the World Trade Center towers used to cause the collapse. If the support structure is eliminated by the explosives, why does the building fall?

Gravity.

So if gravity is the force that brings the building down, how could the north tower come down in less time than it would for an object falling in a vacuum? Even with explosives, the times used by SoCalifer still defy the laws of gravity.

Perhaps the times he used are not the actual times that it took for the towers to collapse. It's simple enough to see when the collapse starts, but deciding when it ends is not as easy. To me, the actual collapse times look much longer than the ones posted.

-Make7

BTW - The actual free falls times would be 9.22 seconds for the North Tower and 9.20 seconds for the South Tower.

How Does That Work?

Make7, I give an answer to that question in the thread that this thread is referencing. Here's a link to the post: http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=132x1598983#1604730




I would also like to point some things out here with video and photo images.

First take a look at this video news clip. Focus your attention along the right side of the building, keeping your attention just a little below the progressing collapse. Two times you will see smoke/dust plumes jetting out the side of the building, very possibly from these explosives.

http://members.cox.net/anti_globalist/wtc-1_jets.mpg




Next in this video news clip if you look closely you'll be able to notice three of the same smoke/dust plumes jetting out of the building on two different points in time. The first two go off at the same time, and to see them, focus your attention on the face of the building facing to the right of the video. They will appear just above the bottom of the video image. The third and last one in this video is actually below the bottom of the video image, but if you pay attention to the face of the building facing to the left side of the video, you'll be able to catch part of the smoke/dust plume at the bottom of the video image.

http://members.cox.net/anti_globalist/north-tower-collapse.avi




This is a video clip I made of excerpts from my copy of 911 in plane site

http://members.cox.net/ducati996sp/In-Plane-Site.wmv





Now take a look at this image. What I see is the top of the WTC breaking away from the tower and falling over the side. It is important to note that at this angle, this top structure should be applying force only to one side of the tower's structure below and little or no force on the other side of the tower's structure. This should cause this top section to break away and fall over the side of the tower. --But-- What we see when we watch the video is that miraculously at this point the tower collapses uniformly below it, thus allowing it to fall straight down.

Another couple of important things to note from this picture is: notice the amount of explosive force the smoke/dust clouds are depicting? And notice the falling steel column beams; see how none of them are bent or twisted? In fact I've looked at dozens of photos of the WTC's collapsing and of the later wreckage and practically none of the steel is bent or twisted -- like as if they were all cut, and most of them at the same lengths.

How does what work?
___________________

"Even more unusual is that the north tower came down in 8.1 seconds." - SoCalifer

If the free fall time for the North Tower is 9.22 seconds, what force was used to make it collapse 1.12 seconds faster? How much force was necessary and how was it transferred to the structure to make the building fall faster than gravity?

How does that work?

-Make7

If I misstated Make7..

I gave a link to where I already described an answer to your question. Sorry if I wasn't clear on that..

I didn't zero in on the relevant passage when I read it. (Lack of sleep = reading comprehension difficulties.) My fault.

Although I would suggest taking the few extra seconds to cut and paste the text that you want to discuss into your replies. It let's everyone coming to the discussion see what is being said without having to jump around to other threads and search for the information. But a link is still extremely useful for those that want to look into things in more detail.

On to the discussion:
__________

"Now if you apply shaped charges to cut the steel column and other ones to knock the columns in and downward to create an implosion type demolition. The knocking downward force being applied to the column will have a "pulling" affect on the build itself -- Not unlike the downward force being applied to a piston on it's power stroke." - SoCalifer
__________

I doubt that this would work on columns that are connected to so many other structural elements. If the column is cut at one point and another charge is detonated to try and force it down, that second charge would be acting against the column and everything still attached to it. The result would either be an insignificant displacement of the building, or damage (or possibly failure) of just that column.

I'm quite sure you will disagree with that conclusion, so I'd like to discuss the questions that occur to me supposing that your scenario was implemented and worked how you described.

How many tons of explosives are needed to accelerate a building weighing over 500,000 tons to the ground with a force that increases the effect of gravity by approximately 30%? I'd venture to guess that it is a lot. An awful lot.

So let's say they planted this enormous quantity of explosives, and they were able to sequence the detonations precisely enough to bring the building down faster than free fall speeds. What would be the purpose? Why would they deliberately cause the building to fall faster than free fall speeds when it is not at all necessary to bring the building down and would only increase the chances of detection, increase the chances of something going wrong, and provide the evidence that explosives were actually used?

Seems like a whole bunch of work for something with so many possible negative consequences and no benefits. Perhaps you could explain why they would bother doing such a thing.

-Make7

weighing over 500,000 tons to the ground...."

Not as much as you might think. Here is something I posted in a thread called "What Goes Up Must Come Down":

I got this special US News and World Report last Christmas. The Magazine was called "Secrets of the Master Builders". The last article, whose title is noted above was quite interesting. It's been sitting in the bathroom and I finally got around to reading this article today.

Anyway, there were 2 interesting paragraphs I thought I'd share.

"The tools of the destructor's trade range from standard dynamite, used to shatter concrete, to linear shaped charges that concentrate the force of the blast. Shaped charges use a high explosive called RDX, slicing through steel with millions of pounds pf pressure per square inch. In 2001 project, for example, a New York gas storage tank built with 5 million pounds of steel took a mere 80 pounds of shaped charges to come down.

And this unrelated paragraph in the same story:

"The Murrah building was but a prelude to the greater disaster on Sept. 11, 2001. Like most Americans, the Loizeaux's {my note: family business is Controlled Demolition International} were transfixed by the televised destruction shortly after the first jet struck the World Trade Center. But they knew then what few Americans realized, or dared to contemplate. "I told Doug immediately that the tower was coming down, and when the second tower was hit, that it would follow," remembers Mark. "I was familiar with the buildings structure, and with all that jet fuel and the massive amount of combustibles, a catastrophic failure was inevitable."

---------------------

Based on the above and your mention of the WTC total weight, it would seem that 16,000 lbs would be needed....but I don't really think that's true....if located in the core with disregard to safety/surrounding damage, I'd bet the job could have been done with 500 lbs of explosives. The building weight and gravity would take care of the rest.

Does that mean the towers fell faster than free fall or does that mean the towers had critical structural elements removed via explosions and was accelerated by gravity?

that was a phrase in Make7's post I was respnding to.

If the towers fell faster than free fall, some additional force was needed to accelerate the mass of the building to ground level at a higher rate than gravity alone.

I hadn't realized I was so incomprehensible today. Hopefully my point was made more clearly in post #33.

-Make7

Just shooting in here. I have never tried to time the collapses myself (and can´t get the videolink working), but I remember reading a thread about it on Letsroll, and the way I remember it, even the guys posting on Letsroll were coming out with something like 12-15 seconds. (For both towers.)

"How many tons of explosives are needed to accelerate a building weighing over 500,000 tons to the ground with a force that increases the effect of gravity by approximately 30%?"

If, as SoCalifer is theorizing, explosives were used to bring down the towers faster than gravity then I am wondering how much additional force is required to make the building fall faster than it would simply by destroying its supporting structure and letting gravity act upon it alone.

In other words - if the fastest the building can possibly fall is 9.22 seconds and he states that it fell in 8.1 seconds, something must have accelerated the rate at which it fell. If he says that the something that did this was explosives, then how many tons of explosives would be needed to add the additional force necessary to make it fall 1.12 seconds faster than it could ever possibly fall due to just gravity acting upon the enormous mass of the building if it was completely unsupported?
__________

"The tools of the destructor's trade range from standard dynamite, used to shatter concrete, to linear shaped charges that concentrate the force of the blast. Shaped charges use a high explosive called RDX, slicing through steel with millions of pounds pf pressure per square inch. In 2001 project, for example, a New York gas storage tank built with 5 million pounds of steel took a mere 80 pounds of shaped charges to come down." - US News and World Report

Did it fall faster than free fall speeds? Were the explosives used to make it fall faster than gravity would allow?
__________

"Based on the above and your mention of the WTC total weight, it would seem that 16,000 lbs would be needed....but I don't really think that's true....if located in the core with disregard to safety/surrounding damage, I'd bet the job could have been done with 500 lbs of explosives. The building weight and gravity would take care of the rest." - Old and In the Way

I agree, you would not need many tons of shaped charges to bring one of the Twin Towers down. Once explosives were detonated to compromise the supports causing the building to collapse, the building weight and gravity would do the work. That's my whole point - gravity actually pulls the building down - even in controlled demolitions. But if it were to fall faster than gravity would pull it down, how much additional force (explosives in SoCalifer's theory) is required to make that happen?

-Make7

the actual point.

Seems to me, it didn't. And what would be the point? Given the huge clouds of dust and debris, I think the actual end point is impossible to establish, at least in the minimum window. From Lared's videos, I think 12-15 seconds is a reasonable range.

But even this time is an amazingly fast drop for a building over 1300 feet high.....I really see nothing impeding the collapse of either tower, no hesitation coming from the internal structure resisting the downward force, particularly the uppermost section of the structures.

The formula the SoCalifer refers to is a good baseline measure for the theoretical fastest time that an object that high could fall to the ground. And it does allow a comparison to the actual event +/- a few seconds. What's missing is a model that would predict an actual collapse time for each tower with the specific circumstances of each crash dialed in.

I agree that an exact time is nearly impossible to discern for the reasons you have stated, but I think 8.1 seconds is way off.

I fail to see the point either. Although I would still like to hear a reason, from someone who believes the North Tower fell faster than free fall speeds, that the people that they think did this would actually want to cause such a thing to happen. I guess I'll just have to wait on that one...

The formula SoCalifer is using is absolutely correct. (But I obviously disagree with his overall conclusions.) Out of curiosity, I did some calculations to find out the different rates of acceleration that would occur for various collapse times and then compared that to the rate of acceleration for gravity.

time of ` ` | rate of ` ` | compared
collapse `` | accel. ` ` | to gravity
(seconds)` | (feet/s^2) |(percentage)
--------------------------------------------
08.1000000 | 41.700960 | +29.666742
08.2235757 | 40.457096 | +25.799017
09.2235757 | 32.160105 | 0.000000
10.2235757 | 26.176433 | -18.605886
11.2235757 | 21.719690 | -32.463872
12.2235757 | 18.311316 | -43.062014
13.2235757 | 15.646539 | -51.347986
14.2235757 | 13.523793 | -57.948542
15.2235757 | 11.805456 | -63.291614

formula used: acceleration = distance*2/time^2

constants used: distance = 1368 feet (height of North Tower) , gravity = 32.160105 feet/sec^2

So using this as a rudimentary calculation, it works out that at a collapse time of 13 seconds almost half (49.66%) of the force of gravity is being expended by the resistance of the building. I do think that a detailed model with the specific circumstances of the collapse, as you suggested, would be very informative. But with so much disagreement on what the circumstances of the crashes and collapses actually were, that doesn't seem very likely.

-Make7

The entire internal resistance of the structural only delayed the entire collapsed by 4-5 seconds from its maximum theoretical rate in a freefall. That works out to about a .054 second delay per floor (6 seconds/110 floors).

One thing when watching the collapse videos; I don't pick up any discernable "hesitation" at the collapse start. Once it begins, it's looks to be a constant rate of fall. I'd expect that at the point of the 1st floor collapse, the next lower floor impacted would hold for at least few seconds before collapsing and each floor collapse after that would have a progressively shorter duration until the point where the increasing mass overcomes the vertical resistance almost instanteously. That scenario would add considerably to the total collapse time, maybe an additional 15 seconds?

It does point out that in order for the tower to collapse in 8.1 seconds there needs to be a 30 percent increase in available energy.

41.7/32.2 = 1.295

That seems to be an awful lot of explosives.

in your post Free Fall and energy conversion in the The Madrid fire, WTC7, and a conversation with my wife this morning thread, but you were calculating the amount of energy of the fall absorbed by the towers breaking apart and being crushed.

Even though I first did the calculation to see how much extra energy was needed for a collapse time of 8.1 seconds, I realized the same formula can be used to find how much of the energy was being used to break apart and crush the building. You came up with a 11.2 second collapse time with 1/3 of the energy destroying the building. I get 11.3 seconds using my calculations. I'd venture to say that's close enough to confirm both our results.



That was my feeling as well.

-Make7

Now if you apply shaped charges to cut the steel column and other ones to knock the columns in and downward to create an implosion type demolition. The knocking downward force being applied to the column will have a "pulling" affect on the build itself -- Not unlike the downward force being applied to a piston on it's power stroke.

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=132x1598983#1604730

How that changes the free fall time is still quite unclear.

I understand the if you create a perpendicular force at the top of the tower and blew out the bottom it falls faster than free fall. That of course assumes the tower remain intact like your drawing, which is impossible given its design.

But there was no force at the top of the tower, so how does it fall faster than free fall?

As I indicated is just a 'crude' drawing. And it was not meant to represent the entire building, but rather it represents just one section of steel column being cut and knocked down.

Now imagine all the other columns on that same floor undergoing the same thing at the same time, pulling the collapsing structure down above it, then this happening again to the undamaged section of those same columns below, and so on and so forth until you reach the end of the line, some where near or at the bottom floors.


(Since I edited the above crude drawing, you might have to refresh this page to see the change: and out of laziness I only edited one of the depictions of the column being knocked down)

I thought your picture represented the whole tower. Since you are talking about individual columns, AZcat is absolutely correct.

As an example if EVERY 10 foot column on EACH floor was hooked up with explosives per your picture, the 110th floor is still 1350 feet in the air. After the initial blast and rotation of the column around its center, the center of the beam is still 1345 feet in the air and now only under the influence of gravity. Nothing has changed.

The lateral force at the top, if coupled with a cutting blast at the bottom, just causes the section to rotate around its center of mass (along with a little lateral translation). The center of mass of the beam section still accelerates at the same rate.

The tower cannot fall faster than free fall - the forces produced by explosive blasts are not continuous (they are an impulse) and will not "push" the tower down any faster.

Down the same as your shove will to a person when you kick their legs out from underneath them..

Just try it yourself with somebody. Kick their legs out from underneath them and shove their chest while they are going down. Your shove will accelerate their fall.. I guarantee you..

Please don't take this question the wrong way, I am just curious if rather or not you have any experience with demolition? I myself have experience back when I served in the U.S. Army -- its not anecdotal.

If I state something from a speculative point of view, I will say as such, or I won't comment about that something at all.

the column to rotate around its mass center, not push down.

Just like if you kicked the legs out from under a person while pushing them off the WTC, they will rotate about their center while falling at free fall speed until terminal velocity is reached.

Caveat - I have been drinking, so please be considerate of small mistakes.

First let's establish what the minimum fall duration for a person is. Since the center of mass is somewhere around your belly button, the quickest fall you could have is if you were released from a suspended horizontal orientation, because there would be no structural members (legs in this case) to interfere with the fall.

Next let's discuss what happens when a person falls without any external interference (i.e. fainting). Since the legs act to slow the fall (muscles provide resistance like springs) the center of mass descends slower than free fall speeds.

Finally we should cover the scenario described in your post, where the legs are kicked out from underneath the person while they are pushed in the chest. This causes the body to rotate, moving the legs out from under the center of mass. Since they are unable to provide less resistance to the fall as in the second scenario, the center of mass descends faster than in that case.


You are comparing the rate of scenario three to scenario two, when you should be comparing it to scenario one - the minimum duration fall - rather than one where the resistance to falling is greatest. Yes, scenario three is faster - the pushing forces do help - but it still isn't faster than scenario one.



Why does it matter if I have any experience with demolition? This isn't a complicated problem requiring knowledge of such, it's an engineering problem that requires knowledge and understanding of Newton's Laws. Forces are forces, whether they are gravitational or chemical in nature.

As I said these are just very crude drawings to just give a general idea. And to be a little less crude, let me point out that the cutting charges are usually situated to look more like what you see in this crud drawing below...

But, I would like to point out that the bases of this debate is one of questioning the accuracy of the formula I gave which is used to determine distance or height or time of a free falling body in vacuum (which means no resistance).

Now we are getting away from some "FACTS" here. And that is: It is a matter of 'fact' that the WTC towers were 1,350 ft in height. It is also a matter of 'fact' the scientific formula for figuring distance or height or time is Distance = (32.16/2) X Time In Seconds Squared. And it is a matter of 'fact' that given the distance of 1,350 ft, this equation works out to 9.16 seconds. --And-- It is also a fact that the towers fell in 10.4 seconds & 8.1 seconds WITH the encountering of objects that would put up substantial resistance.

Now this leave us with some questions.

-- Either the known height of the buildings is wrong.
-- Or the Formula which is just as scientifically established as pie is; is wrong.
-- Or the known time the buildings fell is wrong.
-- Or the buildings had help in their fall.


-- I am sure we can rule out the first as being in error.

-- To challenge the formula given would be equal to challenging the formula for pie.

-- The 10.4 and 8.1 seconds has been timed over and over again. Although it could be possible that there is an error here. The probability however isn't likely - and it would be very easy to test it again for accuracy.

-- So this leaves us with the last possibility and the most likely. That buildings had assistance in their collapse

Thats the crux of the whole post.

Does it describe the expected rate of a "natural" fall or one that was helped along with explosives?

Look at the seismic charts again. Consider the box-in-box construction of the WTC. If there were explosives in the core and spaced out every 15-20 floors, timed to go off so as to be blow the central core as the collapse event reaches each point, the spikes would reflect that (they would amplify the signal down through the building directly to the foundational ground/bedrock).

The visual evidence would be minimized because the core is well inside the building and there's plenty of dust and material that's raining down from the upper floor demolitions.

I'd like to know if, in the design of the building and given its location, was thought given to how the building would be removed? I'd think the most cost efficient and safest removal scenario would be to pancake the floors, one at a time, using the core as a guide. Given the path of least resistance, why weren't those cores be left standing?

Another question conerning the rate of fall. Would not the top quarter disintegration time of each tower be slower than the final quarter? As mass is being added, isn't the force on each floor becoming progressvely greater? Does the film show an increased acceleration of the event? Seems that someone who is good with film editing could analyze the timing of the event to see if the destruction is happening at a constant rate or an accelerating rate.

none of them indicate that

It is also a fact that the towers fell in 10.4 seconds & 8.1 seconds WITH the encountering of objects that would put up substantial resistance.

Please explain how you have determined these times are a fact


Some video I found on the net so you can test the accuarcy for yourself

http://www.screamingpickle.com/members/september11th/video/WTC-Tower1-Collapse.mpg

http://www.screamingpickle.com/members/september11th/video/WTC-Towers1and2collapse.mpg

"Facts are meaningless, you can use facts to prove anything that's even remotely true!" - Homer Simpson

:):):)

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"...I would like to point out that the bases of this debate is one of questioning the accuracy of the formula I gave which is used to determine distance or height or time of a free falling body in vacuum (which means no resistance)." - SoCalifer

Who here is debating that?
__________

"Now we are getting away from some "FACTS" here. And that is: It is a matter of 'fact' that the WTC towers were 1,350 ft in height. It is also a matter of 'fact' the scientific formula for figuring distance or height or time is Distance = (32.16/2) X Time In Seconds Squared. And it is a matter of 'fact' that given the distance of 1,350 ft, this equation works out to 9.16 seconds. --And-- It is also a fact that the towers fell in 10.4 seconds & 8.1 seconds WITH the encountering of objects that would put up substantial resistance." - SoCalifer

Actually the North Tower was 1,368 feet tall and the South Tower was 1,362 feet tall. (PBS)

The formula is correct, but using the actual height of the buildings gives:

- 9.22 seconds for the North Tower
- 9.20 seconds for the South Tower

I don't believe those times of collapse are right, but LARED has already started discussing that point in post #29.
__________

"-- The 10.4 and 8.1 seconds has been timed over and over again. Although it could be possible that there is an error here. The probability however isn't likely - and it would be very easy to test it again for accuracy.

-- So this leaves us with the last possibility and the most likely. That buildings had assistance in their collapse" - SoCalifer

Not only could it be possible that the times you have given are in error, but it is the most likely explanation. Since these times are central to your hypothesis, why don't you cite a source that has accurately measured the times you are using?

I still am not clear on how the North Tower was made to fall faster than gravity would allow. Or even why someone would deliberately attempt to do such a thing.

-Make7

To two points you've made Make7, before I am out the door and on my way to my annual trip to Berkeley, CA to renew my medical marijuana prescription and to vacation for a few days. :)

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

"Not only could it be possible that the times you have given are in error, but it is the most likely explanation. Since these times are central to your hypothesis, why don't you cite a source that has accurately measured the times you are using?"

"I still am not clear on how the North Tower was made to fall faster than gravity would allow. Or even why someone would deliberately attempt to do such a thing." -- Make7


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Yes, it is possible that the times are in error, that you won't get any disagreement with me. But I will reiterate a comment about that though; and that is these times have been done over and over again, so the likelihood of them being wrong, isn't likely in my honest opinion. And I would also like to add: Even if the times are not 100% accurate - They would still be easily close enough to make the same point that these towers fell faster than they should have with all structural resistance in their way while on the way down.

The source where I get the times from? Well, I know this is going to sound cheesy, but I have so many documents and videos concerning the events of September 11th (some from government, some from independent journalist, some from foreign journalist and some from university science and engineer students), that I can't remember right off the top of my head which one I need to dig up and cite for you, LOL, but my memory of the two times remains intact.. :)

And lastly before I must get ready to leave is: To answer your question as to why would someone wish to "deliberately attempt to make the towers fall faster than gravity would allow?" Well, the point is not one of deliberately making a tower fall faster than gravity. The point is a matter of consequence. I am sure they certainly weren't trying to make the towers fall faster -- they just were trying to insure that the towers would fall period. And them falling a little bit faster than normal is just an unintended consequence.


Oh well guys.. I am off.. Time to get ready... :hi:

Let us start from this:


Add this:


And end with this:


You said that someone could set shaped charges to "pull" the building down. Is this to create an implosion type demolition or to "pull" it down faster than gravity?

The free fall time for the North Tower would be 9.22 seconds. It would take a 30% increase in the force of gravity to make it fall in 8.1 seconds. That amounts to an awful lot of explosives for a building weighing over 500,000 tons.

Why would the people who did this deliberately place and detonate so many explosives in order to create an implosion demolition? (Or to make it fall faster than free fall speeds?) That would result in obvious evidence that the plane crash/intense fire explanation was inadequate because there would be clear evidence that other means were used to complete the destruction of the buildings. If they wanted to use explosives, why wouldn't they use as much as would be needed to destroy the vertical integrity of the building and let gravity pull it down? It would still get the job done, but would not leave an obvious sign of foul play. Surely they knew many people would be studying the collapse for years to come. Why tip their hand?

-Make7

P.S. Enjoy Berkeley. :)

WTC 2:

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WTC 1:

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In both cases, the high amplication signal seems to be in a 10 second range, the entire attack/decay of the event runs over 30 seconds.

Those graphs generate a couple of questions to me-

(1) Wouldn't the event record a build up of the signal amplification? I'd expect to see a gradual ramp up in the attack phase and a quicker decay to mark the end of the event. The collapse starts way up in the towers, why large spikes on the front end of the graphs?

(2) Why the 6 or seven large spikes in each event? Is that a function of the equipment's resolution/ability to record the event? I've seen other graphs that are scaled differently that show a much higher single spike for both events.

Well, since none of my schooling involves geology. I wouldn't be in any kind of a position to comment about the various types of seismic waves and their recordings. I would only be speaking from a speculative point of view. So other than seeing your logical view point and agreeing that it raises an interesting question. I have to reframe from any more than that..

But it is a good point Old and In the Way..

A seismogram is a record of the ground shaking recorded by a seismograph.

The P waves travel fastest through the Earth so they arrive at a seismograph first, followed by the S waves and lastly by the surface waves.

The figure above is the seismogram of the 1989 Loma Prieta earthquake recorded at a seismograph in Kongsberg, Norway, 8400 km (about 5,200 miles) away.


http://www.thetech.org/exhibits_events/online/quakes/grams/

http://www.thetech.org/exhibits_events/online/quakes/overview/

recording of the event, correct?

The P wave, I assume would be much closer to the S wave registration, for the WTC tower collapses? Not sure how far Princeton is from NYC, but it can't be more than a 100 mile's, I'd think.

As I understand it they use the time difference between the P and S wave arrivals to determine the location of the event. This of course will require at least two additional recordings from different locations to pin point the epicenter via triangulating.

Because it looks like the arrival of P and S waves overlap in the charts, one would need to know the wave velocities for P and S waves and the distance from the seismograph to the center of the event to determine the length of the event.

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As a computer do you know any computers that were used by demolition experts to create a 'theoretical' demo plan seeing what it would take to make the building demo if they were trying to "pull it" on purpose, perhaps for what would have needed to be done if the buildings hadn't collapsed but were too damaged to rebuild. If you hear anything from your computer friends, please let us know in this thread!

Thanks Grovely, you're the best!

{B^)
FMH

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