How WTC 7 was pulled down

[dtugg]

Also, according to mzelinski's "logic" it should be impossible for explosives to cause a building to collapse (unless tons and tons of the stuff was used). After all, the energy released by the explosives going off would be less than the energy released by the building collapsing.

 

[W.D.Clinger]

That’s the apparent paradox of the NIST’s collapse mechanism, that far more work was delivered at the output than potential work was supplied at the input (First Law). The Second Law would predict that such a situation is not the result of a spontaneous process, that collapse would not proceed in the forward direction.

Psst: You should acquaint yourself with the concepts of potential energy^WP and gravity^WP.

Any high school or freshman-level course on physics should introduce you to those concepts. If you continue to argue physics on this forum, you'll discover that some familiarity with physics comes in handy.

ETA: You are asserting that the Second Law of Thermodynamics would have prevented the collapse from proceeding "in the forward direction". Wouldn't your argument also imply that the Second Law of Thermodynamics permits (or requires) the collapse to proceed in the reverse direction? Why then did the buildings fail to repair themselves following the collapse, as predicted by your calculated entropies?

 

[mzelinski]

If mzelinski's analysis were correct, we could use exactly the same argument to prove that pulling a gun's trigger cannot possibly cause a bullet to leave the gun's barrel at 1000 feet per second. It'd just be a matter of changing the numbers and a few words.

. . . .

That means there must be something wrong with mzelinski's argument. As Newtons Bit said, mzelinski's most important mistake was to assume the kinetic energy all came from the trigger.

. . . .

It’s trivial to show that the force of a finger flex acting over the distance of a trigger pull is far less energy than the kinetic energy of the fired bullet. So, yes, using my analysis above, in fact I would maintain that a bullet traveling 1000 ft/s could not possibly be caused by pulling the trigger alone; an additional energy source would have to have been involved to do the work, namely a shell full of gunpowder.

Rather, the NIST's explanation of the collapse of WTC7 is in effect postulating that the kinetic energy of the bullet is caused by pulling the trigger alone.

Bazant and Cedolin’s Stability of Structures, ch 10, presents a thorough engineering treatment of applying thermodynamics to mechanical structures.

Do you know of a way to show that thermal expansion of a girder in order to bring down WTC7 either does or does not violate the Second Law?

 

[Furcifer]

Do you know if anyone has attempted to show that the NIST’s collapse model does not violate the Second Law?

Are you kidding or do you just not understand the question you are asking?

NIST never attempted to calculate the energy in the initial or final state of WTC7. Why would they? It's the furthest thing I can imagine from a closed system.

You have to kidding because I can't imagine anyone this clueless, except perhaps Net Force=0 Boy

 

[GlennB]

It’s trivial to show that the force of a finger flex acting over the distance of a trigger pull is far less energy than the kinetic energy of the fired bullet. So, yes, using my analysis above, in fact I would maintain that a bullet traveling 1000 ft/s could not possibly be caused by pulling the trigger alone; an additional energy source would have to have been involved to do the work, namely a shell full of gunpowder.

The "additional energy source" at WTC7 was rather like your shell full of gunpowder. It's called potential energy and was installed during the building phase. It involved cranes lifting a lot of heavy material way up into the air, and maybe pumps pumping concrete.

Once there, it was all primed and ready to go off. Your energy balance calculations should have included this.

Hope that helps.

 

[Oystein]

...
What is the change in temperature of the upper block during free fall anyways?

That would mainly depend on how strong the sun shone, how cool the wind blew, and how intense these pesky fires burned...

 

[PhantomWolf]

Or, to put it another way, when I use a firelighter to get my wood stove going I should expect the energy output from the wood to equal the output of the firelighter.

And with several hours of wood being more expensive than a firelighter I should stick to burning firelighters. D'oh! What a fool I've been.

MM - mzelinski's premises were not merely fatally flawed, they were laughably flawed.

I read it twice just to make sure I wasn't missing something that made sense, and finally came to the conclusion that mzelinski is a plant to make Truthers appear even dumber by getting them to agree that word and number salad actually not only makes sense, but that it something amazing.

 

[Oystein]

It’s trivial to show that the force of a finger flex acting over the distance of a trigger pull is far less energy than the kinetic energy of the fired bullet. So, yes, using my analysis above, in fact I would maintain that a bullet traveling 1000 ft/s could not possibly be caused by pulling the trigger alone; an additional energy source would have to have been involved to do the work, namely a shell full of gunpowder.

Rather, the NIST's explanation of the collapse of WTC7 is in effect postulating that the kinetic energy of the bullet is caused by pulling the trigger alone.
...

No. The additional energy was there all along in the form of potential energy (gravity).
On account of the building being 186m high (with the center of mass at maybe 41% of its height, or 76m, from which you might conservatively deduce 5m of average rubble pile height), having a mass of 1.16 * 10E8 kg, and New York experiencing gravity's pull at 9.805m/s², that extra energy works out to
E_P = m * h * g = 80,753,980,000J

That's about 19 tons of TNT, or 21 tons of pure, ideal thermite

 

[Oystein]

...For example, see Robert Gilmore’s Catastrophe Theory, ch 11, "Structural Mechanics" for a concise treatment of buckling modes in elastic theory. Even he concludes that such a structure will merely sag but not collapse (see page 261)...

If this were true, it would be impossible to design a building that collapses totally in a fire, or from other events that increase entropy (all events, that is).

Has this made you wonder why people give money to structural engineers, if building collapse is an impossibility? Apparently, the higher and more massive a building, the lower the possibility of its collapse, right?

 

[Dave Rogers]

Tell me then, what does NIST claim the point of their model is,

To determine the detailed failure mode of WTC7 in order to feed into revised building codes which will improve the resilience of large buildings to widespread files.

and what was the point of them repeatedly claiming the manor in which their model comes down is consistent with the video evidence?

That, for the purposes for which it is intended, their model is a sufficiently close approximation to the actual collapse dynamics, and is therefore a credible basis for imposing modified structural requirements that are certain to add cost to the construction of future buildings. I'm a little disappointed that they pandered to the insane ravings of obsessive lunatics on the Internet to the point of analysing blast events, but apart from that I suspect that the truth movement was correctly considered to be of no significance or relevance whatsoever.

So, as it seems you don't believe NIST analysis with their model was even intended to prove this claim, what analysis do you believe proves it?

Simple observation. WTC7 was observed to be significantly damaged by debris impact, and to suffer prolonged and widespread fires, both phenomena which are known to be capable of causing the collapse of steel-framed buildings. All other known causes of collapse of steel-framed buildings may be excluded on the basis that they were not observed by means certain to observe them had they been present.

Dave

 

[Dave Rogers]

It’s trivial to show that the force of a finger flex acting over the distance of a trigger pull is far less energy than the kinetic energy of the fired bullet. So, yes, using my analysis above, in fact I would maintain that a bullet traveling 1000 ft/s could not possibly be caused by pulling the trigger alone; an additional energy source would have to have been involved to do the work, namely a shell full of gunpowder.

I was going to say that, in the collapse of WTC7, an additional energy source was of course available: the gravitational potential energy of the building, which you have chosen to neglect. But it looks like everybody else has beaten me to it. So I'll just congratulate you on achieving new heights of truther idiocy. The very idea that anyone could imagine that the collapse of a building - a massive increase in disorder, although that's not a particularly rigorous way of looking at it - could violate the Second Law of Thermodynamics is quite incredible. Forget the giggle test; it doesn't even pass the hearty guffaw test.

Dave

 

[TSR]

Something about latex, doctors, temperature. Kinky stuff.

.
Just don't confuse which thermometer is which...
.

 

[Sabretooth]

Hey youre the one who "got physics"over here. I'm waiting for your efforts to support the unsuportable. Go on champion. Bring the full model on, so I can submit it to real scientists who does not subscribe to any belief system of utter denial and prejudice.

What medium or item can cut structural steel, in multiple places, with precision, that not only is very quiet, but also does not produce a blinding flash of light, is fire-proof, and can be applied without being detected either before, during, or after it's use?

As long as this question goes even partially unanswered, the CD/Pull theory is dead. As is the Twoof Movement.

 

[Grizzly Bear]

Eh, the closest thing I've ever seen to "pull it" being used as a demolition term referred to the use of cables to bring the building down. Last I checked nobody saw black ops attaching cables to the building while it was burning so the only option that leaves is fall out is not only confusing terminology, but also repeating a disingenuous out of context quotation. After a few years you'd think at the very least "pull it" would be substituted with something else, but they want to stick on it for some reason... I guess it sounds too catchy to abandon

 

[W.D.Clinger]

It’s trivial to show that the force of a finger flex acting over the distance of a trigger pull is far less energy than the kinetic energy of the fired bullet. So, yes, using my analysis above, in fact I would maintain that a bullet traveling 1000 ft/s could not possibly be caused by pulling the trigger alone; an additional energy source would have to have been involved to do the work, namely a shell full of gunpowder.

Very good! You have identified a large reservoir of potential energy in that system: the chemical energy of the propellant.

To understand why that analogy was relevant to the collapse of a building, you should look for an analogous reservoir of potential energy in an uncollapsed building.

Rather, the NIST's explanation of the collapse of WTC7 is in effect postulating that the kinetic energy of the bullet is caused by pulling the trigger alone.

No. You're overlooking the gravitational potential energy that WTC7 possessed prior to its collapse. Please try again.

Do you know of a way to show that thermal expansion of a girder in order to bring down WTC7 either does or does not violate the Second Law?

Yes. You've been given many broad hints, such as:

Psst: You should acquaint yourself with the concepts of potential energy^WP and gravity^WP.

This may come as a surprise to you, but you can increase the entropy of a system by converting some of its potential energy into heat. Among people who actually understand thermodynamics, that is considered to be one of the more obvious ways to increase the entropy of a system.

The building's collapse converts its gravitational potential energy into kinetic energy. That kinetic energy is short-lived. What happens to it?

Some of that kinetic energy is transferred to the earth, but the earth is so massive that its change in velocity is too small for anyone to notice. Some kinetic energy goes into breaking things. The kinetic energy that doesn't go into changing the velocity of the earth or breaking things or other dissipative activities turns into heat, which increases the entropy of (what's left of) the building.

(Breaking the building into smaller pieces also increases the entropy of the building, but that's a more sophisticated analysis so we'll save it for some other day.)

We can estimate the increase in entropy by calculating the potential energy that was converted into kinetic energy and then into heat and other less useful forms of energy. Oystein has already done that for us:

No. The additional energy was there all along in the form of potential energy (gravity).
On account of the building being 186m high (with the center of mass at maybe 41% of its height, or 76m, from which you might conservatively deduce 5m of average rubble pile height), having a mass of 1.16 * 10E8 kg, and New York experiencing gravity's pull at 9.805m/s², that extra energy works out to
E_P = m * h * g = 80,753,980,000J

That's a lot of potential energy. I don't know how you managed to forget about it.

When you modify your calculation to take into account the conversion of that potential energy into heat (et cetera), you will arrive at conclusions that are diametrically opposed to your incorrect conclusions in post #151.

If you need more help with your calculations, please let us know.

 

[tsig]

Eh, the closest thing I've ever seen to "pull it" being used as a demolition term referred to the use of cables to bring the building down. Last I checked nobody saw black ops attaching cables to the building while it was burning so the only option that leaves is fall out is not only confusing terminology, but also repeating a disingenuous out of context quotation. After a few years you'd think at the very least "pull it" would be substituted with something else, but they want to stick on it for some reason... I guess it sounds too catchy to abandon

They were Invisi-cable^TM.

They're available at the same store where you buy Hush-a-boom^TM and Invisi-crete^TM.

 

[kylebisme]

The NIST analysis is available for perusal by anybody.

NIST's model is not available for perusal, all we have beyond a short video of that model starting to come down is their word that it does what they say it does.

The end result was close enough to the observed event to give high confidence in its accuracy as it shows all the major observed features, collapse of the east penthouse, east to west progression of failure, multistory buckle that allows for the period of near freefall and the general southward collapse of the building.

Surely if NIST's multistory buckle leads to a period of near free fall and general southward collapse close to that of WTC 7, they shouldn't be shy about showing video of that model doing so, eh?

WTC7 was observed to be significantly damaged by debris impact, and to suffer prolonged and widespread fires, both phenomena which are known to be capable of causing the collapse of steel-framed buildings.

Since NIST has been unwilling to show their model actually collapse so we can compare it with WTC 7 ourselves, what example of a steel framed building coming down from impact damage and/or fire would you suggest is most comparable?

 

[Dave Rogers]

Since NIST has been unwilling to show their model actually collapse so we can compare it with WTC 7 ourselves, what example of a steel framed building coming down from impact damage and/or fire would you suggest is most comparable?

Numerous steel framed buildings have collapsed due to fire, and it's trivially obvious that sufficient impact damage is capable of causing a building of any construction to collapse.

Since the truth movement has been unwilling to suggest examples, what example would you suggest as a precedent of a steel framed building coming down from thermite being used to sever support members? Alternatively, what examples can you suggest where a steel framed building was demolished by explosives that failed to produce any discernible sound on nearby recording equipment?

The answer is, there are none. We can therefore rule out both of these possibilities as causes of collapse. We can rule out earthquakes, or insufficiently strong foundations, for reasons that should be obvious. We can rule out demolition using cables or wrecking ball. We can rule out directed energy weapons because only mad people believe they exist.

So, apart from impact damage and fire, we have no viable causes. Therefore, NIST examined those causes only.

Dave

 

[twinstead]

Eventually even truthers need to realize that even if the NIST model was totally wrong, and their report was total garbage, that it would NOT be evidence of inside job or CD. At some point, some actual evidence of CD would need to be presented.

God of the gaps ROCKS!

 

[Dave Rogers]

At some point, some actual evidence of CD would need to be presented.

Oh, that's easy enough to find, and on this very forum too.



See? It was you!

Dave