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"Freefall"

einsteen said:
Dear Hans, steel and copper are good heat conductors. Copper better than steel but steel is a very good heat conductor.

I would expect the Eiffel tower would topple, that's also what the controlled demolition experts do.

Ok Hans, wtc7 was damaged from the beginning and the heat made it weak, after a certain point everything broke inside ? maybe I should put my books out of the dust but I've never heard about this effect.
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Let us also not forget about the complex chemical reactions of steel with the Compounds created in the fires we can not use the estimates of the strengths of the resistance for undamaged steel.

We also have to talk about hydrogen Embrittlement, And Carbon reactions with the oxide coatings, the steel itself was a source of heat in the fires and would have damaged itself.
You have a lot of complex chemical reactions that most people are over looking.

http://www.corrosion-doctors.org/Forms/embrittlement.htm

http://www.chemguide.co.uk/inorganic/extraction/iron.html

Also remember that sulfuric Acid was produced by the fires as the Diesel burned, which would have cleaned the metal and cause new oxidation and exposed new metal to Hydrogen Embrittlement.

People tend to forget that steel is a reactive metal itself, It oxidizes and reacts with other elements when heated.

I have seen the effects of high sulfur petroleum products on even stainless steel, when burning, Although I am not a chemist, I have no doubt but that the reactivity of the compounds involved played a key factor in the collapses of all the buildings.
 
einsteen said:
Dear Hans, steel and copper are good heat conductors. Copper better than steel but steel is a very good heat conductor.
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http://en.wikipedia.org/wiki/Thermal_conductivity#Some_typical_thermal_conductivities_.28k_values.29

Steel conducts heat more than 10 times less effectively than copper. What does this mean? It means that unlike copper, parts of a steel structure can be heated to considerable temperatures while others stay cool.

ETA: My cooking pan is aluminium (almost as good a conductor as copper), but the handle is steel. Yet I can easily touch it.

I would expect the Eiffel tower would topple, that's also what the controlled demolition experts do.
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And?

.... Oh, I know where you're going, and if you wanna do that, I'm game :D .

Ok Hans, wtc7 was damaged from the beginning and the heat made it weak, after a certain point everything broke inside ? maybe I should put my books out of the dust but I've never heard about this effect.
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Everything? No, enough supporting structures broke so that the building could no longer support its own weight. This is called a catastrophic break-down.

Let me spell it out to you:

Suppose a building has 50 columns holding it up. Now, of course a building will be dimensioned with a fair safety margin. So actually, 30 columns are enough to support it. Now, let's say some accident destroys 10 columns. Since each of the columns can carry 1/30 of the building, and they only now carry 1/40, the building keeps standing. Now, fire is weakening a number of the columns. At some point, one is weakened beyond the 1/40 of the building weight it is carrying, so it breaks or bends. The building may sag, but since the rest of the supports can still carry the 1/39 of the building they are now carrying, it stays up. Nnext column fails, now they all have to carry 1/38. Next etc... At the point where we reach 1/30, the next failing column will result in the rest being overloaded, and they will fail in an ever accelerating succession, as more and more suppoers get more and more overloaded.

...

You can make an experiment to show this:

Take something heavy, for instance a bucket of water. Suspend it with a number of thin threads, sewing yarn or the like. It needs to be so that it takes several strings to carry its weight, but you have more than enough.

Now, cut one string at a time. What happens? At some point, the remaining ones all break, in rapid succession, and the weight falls.

Hans

Edited for codes.
 
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Everyone else has pretty well covered your "points", einsteen. But I'll add a bit.

My calculations were based on the assumption of a collapse starting. THey were intended to show that there was a significant difference between the 6.5 seconds it fell and freefall. So the freefall argument is moot.

The energy statements were in regards to the multiple times you've talked about how much energy needed to be taken away to do other things besides accelerate downwards. The proportion of actual fall time squared to freefall time squared calculated above should be identical to the proportion of total energy to the energy used for downward acceleration. This places a cap on the amount of energy available for other actions, such as tossing debris or breaking additional supports.

Of course, I should have explained this better earlier, but I seriously thought that you had at least a basic knowledge of physics. I will no longer assume you have had a high-school physics education, so this type of confusion should not occur again.
 
MRC_Hans said:
In all fairness, Einsteen is not a "free-faller".

Hans
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Au contraire.

He is, he just doesn't realize it. It's the same basic argument, about there being not enough energy available to break the structure and fall as fast as it did. Just because he agrees it wasn't freefall doesn't change the fact that he's making the same argument, and has the same lack of understanding and avoidance of math and physics that they show.

So while technically he may not be a "freefaller", his arguments are identical.
 
einsteen said:
I would expect the Eiffel tower would topple, that's also what the controlled demolition experts do.
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I'm surprised no-one else addressed this. Do you honestly believe demolition experts topple buildings over sideways?
 
Hans I understand your column example but do you remember that movie posted recently about a CD that fails an entire block stays intact, for wtc7 we see it completely disappearing and collapsing to the ground at all levels. And again steel is a very good heat conductor enough to conduct. Ever wonder why steel feels cold when you touch it?
Copper would be much better but steel has the purpose it is strong, copper not. Steel conducts heat good enough to get no gradient if you heat it at one side.

Cuddles, yes they topple buildings, an expert told it in an interview.

Huntsman, again the potential energy is not used to break the structure but to accelerate the mass downwards in the wtc7 case
 
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einsteen said:
Huntsman, again the potential energy is not used to break the structure but to accelerate the mass downwards.
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Are you really this ignorant of physics?

You still fail to understand the issue.

If potential energy is not used to break the structure, then the building should have fallen at a speed as if freefalling, and you refute your own theory.

Part of the structure was weakened enough to allow the structure to fall. The gravitational potential energy accelerated the falling part downward. This falling part would A) impact other parts that had not yet begun to fall, transferring some of it's energy and causing additional structure and support to break and B) initiated impacts that threw out debris and dust. The total energy avaialble to the collapse is equal to the total gravitational potential energy in the structure. This is an upper limit on the amount of energy available, in total, from collapse initiation until the collapse is over.

I'm sorry you don't understand this, but if you truely cannot grasp what is a very basic concept regarding physics and conservation of energy, there's no use going further. You have shown yourself to not only be ignorant, but willfully so, as it would take very little time or education to understand this type of error.
 
einsteen said:
[Cuddles, yes they topple buildings, an expert told it in an interview.
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So all those buildings that have been demolished over the years by collapsing them vertically so they don't damage anything nearby are in fact hoaxes on the part of the conspirators to make us believe that the twin towers could collapse the same way? Or are you just talking out of the wrong hole?
 
einsteen said:
Hans I understand your column example but do you remember that movie posted recently about a CD that fails an entire block stays intact, for wtc7 we see it completely disappearing and collapsing to the ground at all levels.
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So what? Buildings are different. The building in that CD was not a homogenous structure, perhaps it had even been built in several sequences.

Are you now saying that because WTC 7 falls differently from a movie you saw of one CD, it means that WTC 7 was a CD? Or what exactly is it you are claiming?

And again steel is a very good heat conductor enough to conduct. *snip*
Steel conducts heat good enough to get no gradient if you heat it at one side.
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Well, basically that is wrong. There will always be a gradient. But what about it? The point is that a fire can heat parts of the steel structure so that it looses strenght.

Cuddles, yes they topple buildings, an expert told it in an interview.
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What exactly do you mean by "topple"?

Huntsman, again the potential energy is not used to break the structure but to accelerate the mass downwards.
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No. The the
force
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of gravity is what accelerates the mass. The potential energy is the product of the weight and the elevation. This may be nitpicking, but we might as well get the terms right.

Hans
 
Huntsman said:
If potential energy is not used to break the structure, then the building should have fallen at a speed as if freefalling, and you refute your own theory.
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The free-fallers always seem to make the mistake of figuring if gravitational potential energy is used to accelerate something (conversion to kinetic energy), then there is no energy left for destroying it. It seems to me that, at least in the case of WTC7, they're overlooking the fact that all that kinetic energy, when it hits the ground, is spent breaking things up. So you can have both near free-fall speeds and energy to destroy the materials, just at different times.

Einsteen, since the kinetic energy of the falling mass came to an end when it hit the ground, that energy gets used to destroy stuff. It's that simple in the case of WTC7.
 
CurtC said:
The free-fallers always seem to make the mistake of figuring if gravitational potential energy is used to accelerate something (conversion to kinetic energy), then there is no energy left for destroying it. It seems to me that, at least in the case of WTC7, they're overlooking the fact that all that kinetic energy, when it hits the ground, is spent breaking things up. So you can have both near free-fall speeds and energy to destroy the materials, just at different times.

Einsteen, since the kinetic energy of the falling mass came to an end when it hit the ground, that energy gets used to destroy stuff. It's that simple in the case of WTC7.
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Yes, this is true as well :) On impact, the kinetic energy gets converted to mechanical and heat energy (and probably others).

Good catch! I'd missed that one (but then again, I also don't claim to know more than the physics and engineering experts...well, not usually ;)).
 
Cuddels, they topple buildings. Experts like Brent Blanchard and also Jowenko can tell you that, I will not post movies from it because you can find it if you want.

Huntsman, I rechecked and another expert Loizeaux, he says in fact:
The explosives are used as the catalyst and gravity is the engine.

Once it goes it goes, the tremendous amount of kinetic energy will break extremely strong structures. I was more referring to the initial moment, potential energy doesn't break the complete structure, it is the kinetic energy/momentum etc. Strictly speaking I was wrong that I said that the potential energy is only used to get the building down because once it is transformed to kinetic energy that is also used to break some other stuff.
And energy is energy isn't it. Let me correct that.

And in fact Greening already shows that once you only need a fraction of the kinetic energy (ok you are right: comes from the potential energy) to break the structure. The collapse time in the TT case differs only a little bit.

Let me end this posting by noting that for wtc7 both a controlled demolition and a structural failure are consistent with the laws of physics.
However if you know how difficult the technique is (there are only about 20 CD companies) to end with a pile of rubble then I'm more thinking about the first one.

I copy paste something from howstuffworks:

Blasters might also overestimate the amount of explosive power needed to break up the structure, and so produce a more powerful blast than is necessary. If they underestimate what explosive power is needed, or some of the explosives fail to ignite, the structure may not be completely demolished. In this case, the demolition crew brings in excavators and wrecking balls to finish the job. All of these mishaps are extremely rare in the demolition industry. Safety is a blaster's number-one concern, and, for the most part, they can predict very well what will happen in an implosion.
 
einsteen said:
Let me end this posting by noting that for wtc7 both a controlled demolition and a structural failure are consistent with the laws of physics.
However if you know how difficult the technique is (there are only about 20 CD companies) to end with a pile of rubble then I'm more thinking about the first one.
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It's only consistent "with both" if you ignore the vast majority of evidence. The only things you're looking at are one view that shows the top of the building upwind, de-emphasizing the lean of the building, the structural damage, and the huge fires; and some vague notions about the debris pile afterward.

You are conveniently ignoring the several hours of structural degradation noticed by the Fire Department while the thing was burning brightly, the lack of any sound or sight of explosives detonating, the lack of any residue or structural members that show evidence of cutting, and the obvious fact that explosives would not have survived the fire. If you keep this in mind, you will see that structural failure is the only conclusion.

Picking and choosing evidence to fit a preconceived notion is not scientific. We've explained this to you over and over again.
 
But Mr. Mackey have you seen the movie "the building is about to blow up" and also the movie that people where told to leave because... The women with the baby in arms didn't stand there for 7 hours. And there is audio evidence of a women who mentiones a first blast to weaken the structure. There is a guy who talks about a shockwave and windows blowing out.

The lean of the building ? The licensed blasters topple buildings like tree trunks by weakening only one side of the building, there is nothing to be de-emphasized about that. And there are a coupe of experts convinced about the CD.

It's indeed strange that Jowenko for example says that explosives would go of immediately in the TTs and that it takes a year to wire but that the wtc7 could be done quickly because of the few columns it has. I wish the interview was much longer, why don't journalist go to all companies to ask, the VARA (Dutch channel that I don't like politically but that's not relevant) said that nobody has ever asked it. That can't be true, further if the fires are localized you can savely go to the basement of course.
 
einsteen said:
But Mr. Mackey have you seen the movie "the building is about to blow up" and also the movie that people where told to leave because... The women with the baby in arms didn't stand there for 7 hours. And there is audio evidence of a women who mentiones a first blast to weaken the structure. There is a guy who talks about a shockwave and windows blowing out.
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Are you claiming that you have evidence of explosives?

What we know is that WTC 7 was fully evacuated, all firefighters pulled well back in a defensive cordon, hours before it fell.

You expect me to believe that a woman with a baby in her arms stood close enough, for that long, to have been able to tell it was "blown up?" You pick some random guy who claims a "shock wave," one that didn't show up in the same video you watched (it would have broken the windows all at the same instant, no such thing), as more credible than the entire FDNY?

You're grasping at straws, and you're doing it because you're biased. If the effects you describe were so obvious that these people could correctly identify them, it would have been obvious to the literally hundreds of people, professionals, who were intently watching the structure. So they're all either idiots or liars, but these two random people in some bit of Internet video hold the secret? That's your story, right?

einsteen said:
The lean of the building ? The licensed blasters topple buildings like tree trunks by weakening only one side of the building, there is nothing to be de-emphasized about that. And there are a coupe of experts convinced about the CD.
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Depends on the building. Some they do and some they don't. It works much better for short buildings, because the moment arm is shorter and not nearly as much angular momentum must be imparted. It's unlikely a pro blaster would drop WTC 7 in that fashion. Same with WTC 1 and 2.

Besides, this is a non-sequitur. WTC 7 was leaning for hours before it fell. FDNY had a transit on it measuring the lean. CD's do not gradually tip buildings over a period of hours.

Just because some other process could also induces a lean does not mean that a lean necessarily implies that other process. As I have already explained, there are other clues that rule out CD. You have no point.

einsteen said:
It's indeed strange that Jowenko for example says that explosives would go of immediately in the TTs and that it takes a year to wire but that the wtc7 could be done quickly because of the few columns it has. I wish the interview was much longer, why don't journalist go to all companies to ask, the VARA (Dutch channel that I don't like politically but that's not relevant) said that nobody has ever asked it. That can't be true, further if the fires are localized you can savely go to the basement of course.
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Irrelevant.

Placement of explosives would not have survived the fire.

You're assuming, not only were explosives placed, but the people who put them there knew exactly where the fire would start and how it would evolve. Obviously these people have a working crystal ball, in addition to explosives that leave no residue, make no noise, break no windows, trigger no seismographs, bring the building down from the inside first, and fool the combined structural and demolitions experts of NIST and the entire world.

If that sounds paranoid to you, it's because it is.

As before, you have no evidence, only bias.
 
einsteen said:
But Mr. Mackey have you seen the movie "the building is about to blow up" and also the movie that people where told to leave because... The women with the baby in arms didn't stand there for 7 hours. And there is audio evidence of a women who mentiones a first blast to weaken the structure. There is a guy who talks about a shockwave and windows blowing out.

The lean of the building ? The licensed blasters topple buildings like tree trunks by weakening only one side of the building, there is nothing to be de-emphasized about that. And there are a coupe of experts convinced about the CD.

It's indeed strange that Jowenko for example says that explosives would go of immediately in the TTs and that it takes a year to wire but that the wtc7 could be done quickly because of the few columns it has. I wish the interview was much longer, why don't journalist go to all companies to ask, the VARA (Dutch channel that I don't like politically but that's not relevant) said that nobody has ever asked it. That can't be true, further if the fires are localized you can savely go to the basement of course.
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Did you see the movie "Titanic"? :D Facts, please.
 
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