pgwenthold
Penultimate Amazing
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Loose Change - Part II
- Thread starter Kiwiwriter
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Yeah, Mutton-Head, you have to keep in mind the state of mind these people (the people on the scene) were in at the time. Nobody knew what the hell was going on. Airplanes hit the buildings, people were falling from the towers, people screaming, crying, all kinds of rumours going around of highjacked planes, bombs, what have you! You can't expect the firefighters to have a clear and sound view of the situation. Usually they go into a fire, that's what they are used to. But this was WAY BEYOND ANYTHING THEY COULD EVER HAVE IMAGINED. This was a major crisis, nobody knew who was attacking, nobody knew what was to come, if the attacks were over of if there were more horror yet waiting to happen. The US was at war. An unknown and cowardly assaillant had struck with unimaginable force. All hell broke loose. These firefighters saw two of the highest buildings in the world collapse on top of them with hundreds of their collegues and thousands of innocent civilians trapped inside. You can't expect them to give exact accounts of what they had seen. Everything was possible to them, even bombs. That doesn't mean we have to take their exact word for it.
They were in SHOCK
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rwguinn
Penultimate Amazing
Like most of us, Gravy has his "bovine-processed alfalfa" filter set to narrow pass. None of us are particularly polite to the intentionally ignorant.
As my father used to say--you're so mentally bankrupt you can't even pay attention!
That translates, BTW, to "you are dumber than a box of rocks"
Now, now, let's keep from doing that. Mutton-Head was mistaken into believing Gravy was refering to him. End of story.
I believe Mutton-Head is sincerely raising his own questions about the collapse and I believe he is genuinely trying to have an honest debate. Let's keep this cool.
geggy on the otherhand was another story, he totally deserved everything he got.
Honest, non-confrontational reply to Mutton-Head
Holy moley this thread moves fast!!
Anyway, I felt that Mutton-Head asked a valid question, and wanted to give a (hopefully) educational answer.
Allow me to summarize your observation -- please feel free to correct me if I misinterpret you in any way:
1. The potential energy (gravity) of the standing structure is the only officially accepted source of destructive energy for the bulk of materials in WTC 1 and 2, since each aircraft itself affected a relatively small number of floors.
2. The amount of energy appears insufficient to comprehensively pulverize the materials.
3. Therefore, a new and secret source of energy must have been present.
4. It is suggested that this additional energy was in the form of high explosives.
Good enough?
This is a perfectly rational question to ask. One need not be a Conspiracy Theorist to wonder whether gravity alone could do such damage. So let me focus on the second point above. If we find that Point 2. is plausible, then 3. and 4. are reasonable conclusions. If our estimate conflicts with Point 2., then the collapse is believable as-is and no "hidden" energy is needed.
So how much energy are we talking about? We can produce a reasonable estimate using first-year undergraduate physics. No need to rely on others' calculations.
From the excellent article "Why Did the World Trade Center Collapse? Science, Engineering, and Speculation", Eager and Musso, JOM, 53 (12) (2001), pp. 8-11 (readable here: http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html), the above-ground height of the Towers was approximately 411 m, and their mass was each roughly 500,000 metric tons, or 500,000,000 kilograms.
The potential energy of a suspended object is equal to:
PE = (mass) * (gravitational acceleration) * (height)
where on Earth, gravitational acceleration is approximately 9.8 meters per second. Let's estimate the energy of one tower.
If we assume the density of the tower is constant [1], then the cross-sectional density of the tower is given by:
d = (mass) / (height) = 1.22x10^6 kg / m.
The total potential energy due to gravity of the standing tower is computed via the following integral [2]:
PE = {Integral Sign} d g h dh
where d is the cross-sectional density from above, g is the gravitational constant, and h is the height running from 0 to 411 meters. Since our d is constant, it is an easy integral to evaluate:
PE = d g h^2 / 2 evaluated from 0 to 411 meters, or
PE = 1.01 x 10^12 kg m^2 / s^2, = 1.01 x 10^12 Joules.
Let's say for sake of argument [3] that only some of the energy is available to crush materials, since the rest of it is "needed to accelerate the tower downward." Following the discussion above, let's suppose that 30% is used to fracture the materials, with the rest going elsewhere. This 30% is 3.03 x 10^11 Joules.
How much energy is this in practical terms? Well, you mentioned explosives. Taking Trinitrotoluene [4] as a baseline, the potential energy of this explosive is 4184 Joules per gram. In other words, to replicate this amount of energy, you would need roughly 72,000 kilograms of TNT.
This is a bit more than the entire payload of two B-52 Stratofortress heavy bombers directed at a single building -- assuming military bombs were pure explosive by weight, which they are not (they average 10% to 25% explosive by weight if my memory serves). CNN and two recent wars in Iraq have given us plenty of examples of single bombs detonated in concrete and steel structures, so it should be obvious that we are discussing a vast destructive force. Furthermore, our collapsing tower is far more efficient, since the gravitational energy affects the structure uniformly, rather than being concentrated at one or more points of detonation.
If, as you claim, this is not enough energy to cause the destruction seen (I believe that it is), and that explosives are the likely candidate, then you are claiming that much, much MORE than 72,000 kg of high explosives were needed.
This is already a stupendous amount of explosives. Several truckloads. Per tower. I don't buy it.
Therefore, I conclude that our conjecture is false, and there was plenty of potential energy stored in the structures themselves. Do you agree?
I've shown you my math. If you disagree, how did you reach your conclusion?
----
[1] Good enough for a back-of-envelope calculation, but probably not accurate. If we assume the tower gets lighter as you move upwards in a linear fashion (linear taper), rerunning these calculations gives you a total energy that is 33% smaller. This is not sufficient to change our conclusions.
[2] You can avoid the integral if you know where the centroid of the building is, and consider the entire building as a point mass at the centroid. If you don't, finding the centroid requires integration similar to the one above. I present the above as a general method to find the total energy in a single step.
[3] This observation is totally incorrect and violates conservation of energy. The "kinetic energy" of the falling tower will be converted to another form once the tower stops falling, as well. The tower will fall on its own debris and further pulverize itself on impact. The "30%" available represents only pulverization during the fifteen seconds of collapse, but the "cost of freefall" is only a temporary cost, and will be converted back into thermal energy as the falling tower grinds to a halt.
[4] Source: http://en.wikipedia.org/wiki/Trinitrotoluene I am not a Master Blaster and do not have better data on explosives. There are more potent explosives than TNT (RDX, for instance), but at best this will save you a factor of 2 or 3 in the total mass of explosive needed. Exotic chemicals are also harder to covertly manufacture and easier to detect after detonation.
Taking the revised assumptions in [1] and [3] into account, the correct estimate is roughly 160,000 kg of TNT equivalent -- 0.16 kilotons -- per tower.
Disclaimer: This is a rough estimate from first principles. I am not a structural engineer. Much better analyses exist in peer-reviewed literature.
Eta: Had a "weight" that should have been a "mass." oops.
Holy moley this thread moves fast!!
Anyway, I felt that Mutton-Head asked a valid question, and wanted to give a (hopefully) educational answer.
Allow me to summarize your observation -- please feel free to correct me if I misinterpret you in any way:
1. The potential energy (gravity) of the standing structure is the only officially accepted source of destructive energy for the bulk of materials in WTC 1 and 2, since each aircraft itself affected a relatively small number of floors.
2. The amount of energy appears insufficient to comprehensively pulverize the materials.
3. Therefore, a new and secret source of energy must have been present.
4. It is suggested that this additional energy was in the form of high explosives.
Good enough?
This is a perfectly rational question to ask. One need not be a Conspiracy Theorist to wonder whether gravity alone could do such damage. So let me focus on the second point above. If we find that Point 2. is plausible, then 3. and 4. are reasonable conclusions. If our estimate conflicts with Point 2., then the collapse is believable as-is and no "hidden" energy is needed.
So how much energy are we talking about? We can produce a reasonable estimate using first-year undergraduate physics. No need to rely on others' calculations.
From the excellent article "Why Did the World Trade Center Collapse? Science, Engineering, and Speculation", Eager and Musso, JOM, 53 (12) (2001), pp. 8-11 (readable here: http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html), the above-ground height of the Towers was approximately 411 m, and their mass was each roughly 500,000 metric tons, or 500,000,000 kilograms.
The potential energy of a suspended object is equal to:
PE = (mass) * (gravitational acceleration) * (height)
where on Earth, gravitational acceleration is approximately 9.8 meters per second. Let's estimate the energy of one tower.
If we assume the density of the tower is constant [1], then the cross-sectional density of the tower is given by:
d = (mass) / (height) = 1.22x10^6 kg / m.
The total potential energy due to gravity of the standing tower is computed via the following integral [2]:
PE = {Integral Sign} d g h dh
where d is the cross-sectional density from above, g is the gravitational constant, and h is the height running from 0 to 411 meters. Since our d is constant, it is an easy integral to evaluate:
PE = d g h^2 / 2 evaluated from 0 to 411 meters, or
PE = 1.01 x 10^12 kg m^2 / s^2, = 1.01 x 10^12 Joules.
Let's say for sake of argument [3] that only some of the energy is available to crush materials, since the rest of it is "needed to accelerate the tower downward." Following the discussion above, let's suppose that 30% is used to fracture the materials, with the rest going elsewhere. This 30% is 3.03 x 10^11 Joules.
How much energy is this in practical terms? Well, you mentioned explosives. Taking Trinitrotoluene [4] as a baseline, the potential energy of this explosive is 4184 Joules per gram. In other words, to replicate this amount of energy, you would need roughly 72,000 kilograms of TNT.
This is a bit more than the entire payload of two B-52 Stratofortress heavy bombers directed at a single building -- assuming military bombs were pure explosive by weight, which they are not (they average 10% to 25% explosive by weight if my memory serves). CNN and two recent wars in Iraq have given us plenty of examples of single bombs detonated in concrete and steel structures, so it should be obvious that we are discussing a vast destructive force. Furthermore, our collapsing tower is far more efficient, since the gravitational energy affects the structure uniformly, rather than being concentrated at one or more points of detonation.
If, as you claim, this is not enough energy to cause the destruction seen (I believe that it is), and that explosives are the likely candidate, then you are claiming that much, much MORE than 72,000 kg of high explosives were needed.
This is already a stupendous amount of explosives. Several truckloads. Per tower. I don't buy it.
Therefore, I conclude that our conjecture is false, and there was plenty of potential energy stored in the structures themselves. Do you agree?
I've shown you my math. If you disagree, how did you reach your conclusion?
----
[1] Good enough for a back-of-envelope calculation, but probably not accurate. If we assume the tower gets lighter as you move upwards in a linear fashion (linear taper), rerunning these calculations gives you a total energy that is 33% smaller. This is not sufficient to change our conclusions.
[2] You can avoid the integral if you know where the centroid of the building is, and consider the entire building as a point mass at the centroid. If you don't, finding the centroid requires integration similar to the one above. I present the above as a general method to find the total energy in a single step.
[3] This observation is totally incorrect and violates conservation of energy. The "kinetic energy" of the falling tower will be converted to another form once the tower stops falling, as well. The tower will fall on its own debris and further pulverize itself on impact. The "30%" available represents only pulverization during the fifteen seconds of collapse, but the "cost of freefall" is only a temporary cost, and will be converted back into thermal energy as the falling tower grinds to a halt.
[4] Source: http://en.wikipedia.org/wiki/Trinitrotoluene I am not a Master Blaster and do not have better data on explosives. There are more potent explosives than TNT (RDX, for instance), but at best this will save you a factor of 2 or 3 in the total mass of explosive needed. Exotic chemicals are also harder to covertly manufacture and easier to detect after detonation.
Taking the revised assumptions in [1] and [3] into account, the correct estimate is roughly 160,000 kg of TNT equivalent -- 0.16 kilotons -- per tower.
Disclaimer: This is a rough estimate from first principles. I am not a structural engineer. Much better analyses exist in peer-reviewed literature.
Eta: Had a "weight" that should have been a "mass." oops.
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In fact there was "red molten metal" seen under building 6. Yet no one cries thermite under building 6.
I'm guessing aluminum mixed with other hot debris.
pbs (dot) org/americarebuilds/engineering/engineering_debris_06 (dot) html
(There also a photo)
RICH GARLOCK: Going below, it was smoky and really hot. We had rescue teams with meters for oxygen and carbon dioxide. They also had temperature monitors. Here WTC 6 is over my head. The debris past the columns was red-hot, molten, running. I did some quick numbers with Gary Panariello, an engineer from Thornton-Tomasetti, to try and determine what the load on WTC 6 was and how much of the lateral system of the building the contractor could take down. There were a lot of judgment calls; people had immediate needs and needed immediate responses.
I'm guessing aluminum mixed with other hot debris.
pbs (dot) org/americarebuilds/engineering/engineering_debris_06 (dot) html
(There also a photo)
RICH GARLOCK: Going below, it was smoky and really hot. We had rescue teams with meters for oxygen and carbon dioxide. They also had temperature monitors. Here WTC 6 is over my head. The debris past the columns was red-hot, molten, running. I did some quick numbers with Gary Panariello, an engineer from Thornton-Tomasetti, to try and determine what the load on WTC 6 was and how much of the lateral system of the building the contractor could take down. There were a lot of judgment calls; people had immediate needs and needed immediate responses.
Gravy
Downsitting Citizen
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Thanks for your thoughtful post, R.M. I anticipate the main objection to your math would be the mass of the tower. I've used figures as high as 450,000 kg, but the prevailing wisdom, if it can be called that, seems to be leaning closer to 350,000. I tend to think that there must be someone with OCD out there who's attempted to account for the mass of the mechanical systems, plumbing, lighting, furnishings, electronics, paper, aircraft parts, etc. I suspect that NIST would say such an estimate isn't necessary to account for the destructive forse of the tops of the buildings, but it would be good to know anyway. As it is it seems like everyone is wildly speculating about an important starting figure.
Gravy
Downsitting Citizen
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Here's the fixed link: http://www.pbs.org/americarebuilds/engineering/engineering_debris_06.html
Also, explosions "like demolitions charges" going off in 6 when 2 came down, but we know there were no demolitions charges there.
Scary!
ETA: Thanks, Kent1. That whole site is fascinating.
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Yup, which is why I put in a reference. I didn't pull that number out of thin air.
Still, even if the figure is 350,000 metric tons (not 350,000 kg, that's nothing!), it only reduces my final figure from 0.16 kilotons to 0.112 kilotons of TNT per tower. We're still dealing with an unfathomable amount of potential energy. No conventional bombs, not even fuel-air explosives, approach that kind of power.
kookbreaker
Evil Fokker
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I'm not impressed with these accounts. Red hot metal is not molten metal, and people saying 'molten metal' may not be properly describing what they are seeing. I want pictures and videos before I believe molten steel was there. Not random comments.
Gravy
Downsitting Citizen
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Agreed! And I was just using kilos to see if you were paying attention. Ahem.
Your exactly right. In fact when someone says "red hot metal", it means around 700C-800C. So it can't be molten liquid steel.
Steel Melts at around 1500C
But it can be aluminum which melts at 660C
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kookbreaker
Evil Fokker
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Except that molten aluminum is not red or glowing.
Maybe, it was past the columns like he said, maybe out of the pictures range. Who knows, either way its not steel.
Another note is that you can have melted steel under 1000C, (slag) but its through a eutectic mixture.
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Let me fix an error "red" can be 500-800C
Regnad Kcin
Penultimate Amazing
It's unfortunate you're getting tired, but my point still stands. A person, under great duress at the time, describing a sound, does not for worthwhile evidence make.
Of course. But earwitness testimony, like eyewitness testimony, is notably unreliable; people can and do make mistakes, never mind their methods of description often suffer from hyperbole.
You've no doubt heard this:
"When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck." -- James Whitcomb Riley, written around 1883-1885
Just hearing a quack does not mean there's a mallard in the brush.
Regnad Kcin said:
Here is your exact quote, which I responded to with the two-or-three-billion guess:Mutton Head said:
"...I would have reconstructed the towers.
...Oh come on, when a plane is blown-up in mid-air this is standard procedure. Are you telling me it’s too much of a leap to apply to a building? Especially the largest terrorist attack ever in US history..."
Seems pretty clear.
By the way, the ellipses are mine, where I edited out another poster's words that you were responding to. The full text can be found in post #253.
I apologize in advance if this angers you, but I responded to a very specific suggestion you made, and in doing so indicated its absurdity. That you then suggested I didn't read what you said is in error. Please again see post #253.
"I would've reconstructed the towers" does not mean anything but what it means.
cloudshipsrule said:
Someone (perhaps Gravy) has compiled a list of the agencies who aided in the detective work in regard to the physical events of that day; it numbers somewhere around 40, if I remember correctly. Of those numerous groups, many, many individuals were involved in the gathering and analysis of the information, and their expertise has contributed to the conventional wisdom. You may, for whatever reason, be unsatisfied with their findings. What can I say.Mutton Head said:
Mutton-Head
Critical Thinker
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Holy Majoley but this has grown.
Yowza
First off, sorry if it got too heated. I understand. Apologies to Gravy.
Now, R Macky said it exactly
100% right on what I'm trying to convey. Thank you Macky, that was it exactly. I see your mathematical explanation. (I admit, it's been years since college physics.) There seems to be dispute though over those numbers for mass. Also, I believe that 30% to crush the structure and throw material and pulverize concrete is not enough. I believe it would be much higher. My intuition (and other researchers) tells me that even 100% would not have been enough. But, that's only my intuition, so for now, that discussion will have to wait.
Thanks for info on the firemen. That may be my next course of research. Perhaps I can get information from/about these guys that extends beyond Google and People magazine. Man I'd sure love to talk to some of them.
Thanks to Manny for the fire fighters union. However, I have to admit that it makes me chuckle. I can hardly even get MY union representatives to call me back, and I pay them $800 bucks a year. Ha!
I don't trust the NIST report. Also to Manny, my assertion that they ignored the central steel core wasn't an outrageous lie. It was an exageration. The NIST grossly misrepresented it.
For every single hypothetical question that evreybody has asked, I have at least one or two good hypothetical answers, that make sense, and are plausable, in my opinion. That's why I keep digging. If I find anything that I think is significant, I will let you all know.
Rock on
Yowza
First off, sorry if it got too heated. I understand. Apologies to Gravy.
Now, R Macky said it exactly
100% right on what I'm trying to convey. Thank you Macky, that was it exactly. I see your mathematical explanation. (I admit, it's been years since college physics.) There seems to be dispute though over those numbers for mass. Also, I believe that 30% to crush the structure and throw material and pulverize concrete is not enough. I believe it would be much higher. My intuition (and other researchers) tells me that even 100% would not have been enough. But, that's only my intuition, so for now, that discussion will have to wait.
Thanks for info on the firemen. That may be my next course of research. Perhaps I can get information from/about these guys that extends beyond Google and People magazine. Man I'd sure love to talk to some of them.
Thanks to Manny for the fire fighters union. However, I have to admit that it makes me chuckle. I can hardly even get MY union representatives to call me back, and I pay them $800 bucks a year. Ha!
I don't trust the NIST report. Also to Manny, my assertion that they ignored the central steel core wasn't an outrageous lie. It was an exageration. The NIST grossly misrepresented it.
For every single hypothetical question that evreybody has asked, I have at least one or two good hypothetical answers, that make sense, and are plausable, in my opinion. That's why I keep digging. If I find anything that I think is significant, I will let you all know.
Rock on
Ramooone
Thinker
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heres a good picture of warped steel from the trade center.
http://www.pbs.org/americarebuilds/artifacts/artifacts_10.html
http://www.pbs.org/americarebuilds/artifacts/artifacts_10.html
Thermite bombs
Just a quick note on thermite bombs:
Very easy to make, used often during the Rhodesian war. They are NOT explosive, just to make the point.
Take equal quantitities of aluminium powder and ferric oxide, mix well, make two piles on railway track, roughly a meter apart, bung in a bit of magnesium tape, light and retire.
Wait for metal to cool and walk off with a meter of railway track.
I inadvertantly made a thermite bomb while grinding down a VW alternator bracket on a grindstone which was mounted on a very rusty support structure. Sparks ignited the aluminium filings/rust flakes and suddenly I had drops of molten metal burning holes in the floor. Adding water made life even more interesting for a period...
EB.
Just a quick note on thermite bombs:
Very easy to make, used often during the Rhodesian war. They are NOT explosive, just to make the point.
Take equal quantitities of aluminium powder and ferric oxide, mix well, make two piles on railway track, roughly a meter apart, bung in a bit of magnesium tape, light and retire.
Wait for metal to cool and walk off with a meter of railway track.
I inadvertantly made a thermite bomb while grinding down a VW alternator bracket on a grindstone which was mounted on a very rusty support structure. Sparks ignited the aluminium filings/rust flakes and suddenly I had drops of molten metal burning holes in the floor. Adding water made life even more interesting for a period...
EB.
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