Tower Collapse Questions for Critical Thinkers

This is a wildly inaccurate recount of the observable phenomena.

That video nicely shows the unevenness of the collapse.Due to the tilt there's a whole section of wall that's left standing after the upper block has descended.It also shows how the collapse progresses due to failure of connections between floors and columns.

outerwallpanelsWTC2.jpg
 
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That means that voltage favors the path of least resistance. If you care to, you can find that and more explained .

Ohms law does not state this.

You do understand the difference between the voltage across a resistance and the current being drawn thought the resistance, right?
 
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No it isn't.

No it doesn't.

Your analogy has failed. Time for you to get a new one.
Your completely unsubstantiated denials demonstrate the lack of sold ground from which you argue. Again, it seems rather obvious at this point that you've just got your empty hand in your pocket, waving it around trying to pretend like you have something there.
 
That video nicely shows the unevenness of the collapse.Due to the tilt there's a whole section of wall that's left standing after the upper block has descended.It also shows how the collapse progresses due to failure of connections between floors and columns.

http://img.photobucket.com/albums/v499/swampmonster/outerwallpanelsWTC2.jpg
I was referring to the horizontal nature of of the floors going out during the beginning of the, well before image you presented. Of course some outer columns stood longer than others.
 
Yet I never said anything to suggest the path of least resistance is a law of physics. That said, it is wrong to claim otherwise in such general terms. As Arus mentioned, the path of least resistance is a law of the physics of electricity, commonly known as Ohm's Law. Of course we are not talking about electricity, here but rather mass, and in the case of mass the path of least resistance is a principle of physics.


A principle that does not apply to collisions or collapses.

I never suggested he [R.Mackey] did [make a mathematical error], but rather am taking issue with the conceptualization he used to derive his equation. Again, the potential energy of the system in question is not relative to the whole of the mass of the tower suspended at the maximum height of the tower. Dividing that value by 3 does nothing to change that.


What a strange claim. The potential energy of the system obviously does depend on the building's mass and height, as well as the distribution of the mass over that height. The distribution determines the coefficient (which would be 1.0 if all the mass were at the top, 0.5 if the mass were distributed evenly, 0.0 if all the mass were at ground level, and so forth; the actual result given a more accurate assessment of the mass distribution was 0.33). You would prefer a result presented in terms of the mass and height of some different building?

But even more to the point, if you do not agree with the results of R.Mackey's calculations, then you should be able to point out his error. You can't claim the results are wrong and also claim that you're not suggesting he made an error. Not and retain any credibility.

Bad arguments will not get you a place at the table, let alone a new investigation. Try to do better.

Respectfully,
Myriad
 
As R.Mackey said earlier,the tilt of the tower was only equivalent to a 2 story difference between sides(maximum) at the point of collapse and with the amount of debris being ejected by the collapsing building that small difference is hard to pick.

Go straight to the source.

1) "Tilt of approximately 3 to 4 degrees to the south and 7 to 8 degrees to the east occurred before bulding section fell." NIST NCSTAR1-6D, Table E-1.

2) A graphical representation of the stress at the moment of collapse initiation (predicted) is given in NCSTAR1-6D, figures 4-120.

3) Not directly, no. The columns above can only transmit a force through them equal to their individual buckling strength, which does not account for the magnitude or complexity of impacts at the interface. Force and destruction are also not directly related quantities in any event.
 
Yet I never said anything to suggest the path of least resistance is a law of physics. That said, it is wrong to claim otherwise in such general terms. As Arus mentioned, the path of least resistance is a law of the physics of electricity, commonly known as Ohm's Law.

No. Period. If you can get your hands on an introductory circuit theory textbook, what you want to look up is called the "current divider theorem".
Or you could read the Wiki "current divider" article, which correctly lays out the math.

Simply put, the ratio of the currents in two parallel circuit branches will be equal to the inverse of the ratio of their individual impedances.

Ohm's Law, BTW, is basically a special case of Kirchoff's Voltage Law for circuits having only a single loop, and neither says anything at all about a "path of least resistance".

Linear mechanical systems can sometimes be analyzed in terms of an electrical equivalent circuit (this is not uncommon for loudspeakers), but trying to drag nonexistent "laws" out of circuit theory and use them to prop up troofer misconceptions is just not on.
 
Your completely unsubstantiated denials demonstrate the lack of sold ground from which you argue. Again, it seems rather obvious at this point that you've just got your empty hand in your pocket, waving it around trying to pretend like you have something there.

Your misunderstanding of basic electricity is not our fault. Ohm's Law only applies to electric circuits and has nothing to do with building failures.

Unless you are arguing that a powerful current was passed thru the steel skeleton of the building causing them to heat and weaken.
 
No. Period. If you can get your hands on an introductory circuit theory textbook, what you want to look up is called the "current divider theorem".
Or you could read the Wiki "current divider" article, which correctly lays out the math.

Simply put, the ratio of the currents in two parallel circuit branches will be equal to the inverse of the ratio of their individual impedances.

Ohm's Law, BTW, is basically a special case of Kirchoff's Voltage Law for circuits having only a single loop, and neither says anything at all about a "path of least resistance".

Linear mechanical systems can sometimes be analyzed in terms of an electrical equivalent circuit (this is not uncommon for loudspeakers), but trying to drag nonexistent "laws" out of circuit theory and use them to prop up troofer misconceptions is just not on.

Smarty pants, and you wonder why us hammer and spanner guys dislike you electronic pinkies. ;)
 
Yet I never said anything to suggest the path of least resistance is a law of physics. That said, it is wrong to claim otherwise in such general terms. As Arus mentioned, the path of least resistance is a law of the physics of electricity, commonly known as Ohm's Law. Of course we are not talking about electricity, here but rather mass, and in the case of mass the path of least resistance is a principle of physics.

Oh, my aching head.

As you've already been shown, Ohm's Law is not the "path of least resistance." There is an analogy between electrical impedance and coupled spring response, but really, there is nothing even faintly applicable to the collapses here.

Ohm's Law is also not "The Path of Least Resistance." Furthermore, "The Path of Least Resistance" is not a physical law or even a physical principle. It is a consequence of certain situations -- ones which are not found at the World Trade Center. I wrote up an explanation just last month for people like you.


Right, he also divided that by 3.
I never suggested he did, but rather am taking issue with the conceptualization he used to derive his equation. Again, the potential energy of the system in question is not relative to the whole of the mass of the tower suspended at the maximum height of the tower. Dividing that value by 3 does nothing to change that.

In my last reply, somewhat in jest, I referred you to the "integral sign" in my derivation. Apparently you really don't know what that means. The division by 3 is not at all arbitrary; it is, in fact, a pretty good representation of the actual Tower. Anyway, what we learn from this is that you cannot follow even a simple potential energy calculation, even when all the work is shown for you and dumbed down to a high school sophomore level.

In simple terms, newtons. Of course the structural integrity of a mass is dependent on where it interacts with another mass in a particular situation, and for an interconnected system of masses deriving such values becomes exceedingly complicated. That said, a quick Google search brought up a decent overview of this problem which might help clarify the matter.

No. A Newton is a unit of force. Structural integrity is not equivalent to a force. As I said, the structural integrity is not a well defined quantity. How well a structure will perform under load is not an intrinsic property of the structure. You have to specify the conditions in much more detail. For instance, two forces that arrive at different angles may have dramatically different effects on the structure.

This is why my calculation does not attempt to gauge "structural integrity." Can't be done. Instead, I looked at energy absorption. And that, again, is what you asked for, even though you've run far away from that discussion ever since.

The inertia of the parts of the system are elements of its structural strength, and you are arguing the tower fell as quick as it did because it couldn't provide any more structural integrity than provided by the inertia you attempted to calculate it did.

I cannot emphasize enough how nonsensical the above is.

"Interia" is not "elements of structural strength." Inertia is, depending on how you're looking at it, either mass or momentum. It has units of kilograms or Newton seconds, respectively. The WTC Towers have the same inertia before and after the collapse, although clearly the structural integrity before versus after is radically changed.

The point which you keep missing, for reasons that are now only too obvious, is that the timing of the "crush-down" style collapse is primarily governed by the mass of the structure and its contents. It is momentum transfer that slows the descent. The strength of the lower block also slows the descent, but not much, practically a round-off error. You could double the strength of the WTC Towers without changing the mass and hardly notice the difference.

That is what BLBG shows, and that is why your fantasies about explosives are singularly idiotic. The structure was coming down. If you want to speed up the collapse, the only way you can do it is by literally rocketing the lower structure to the ground in advance of the descending upper block, or else to ripple-fire the different floors so that there are no collisions at any time. I trust even you will agree that this is ludicrous.

I'm not familiar with the videos you allude to, but since you have just suggested the collapse of the towers happening so fast is comparable to some form of demolition, it seems we have come to an agreement here.

The videos with which you are not familiar describe a particular type of demolition, in which a single floor's worth of supports is suddenly destroyed through cables and hydraulics. This leaves an upper section to fall upon the lower portion, which is frequently much larger than the upper part. The entire structure is destroyed, despite no weakening at all being applied to the lower portion.

This is a pretty good model for a WTC Tower collapse that plays exactly like NIST, Dr. Bazant, and Dr. Seffen all say it did. It has no explosives anywhere, nor any needed. It proves the theory that I've presented and that you cannot grasp, by experiment. At this point, the game is over, and it's time for you to go home.

As I said, it is now extremely clear where your mistakes are coming from. You know absolutely nothing about science, yet you act as though you do. You don't even know what inertia is, for crying out loud! Therefore, regarding your Truth Movement proclamations, there is no reason for anyone to listen to you.

I'm done with you unless you want to learn. In that case, we can help.
 
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(snipped for length)
Oh, my aching head.

-

This is a pretty good model for a WTC Tower collapse that plays exactly like NIST, Dr. Bazant, and Dr. Seffen all say it did. It has no explosives anywhere, nor any needed. It proves the theory that I've presented and that you cannot grasp, by experiment. At this point, the game is over, and it's time for you to go home.

As I said, it is now extremely clear where your mistakes are coming from. You know absolutely nothing about science, yet you act as though you do. You don't even know what inertia is, for crying out loud! Therefore, regarding your Truth Movement proclamations, there is no reason for anyone to listen to you.

I'm done with you unless you want to learn. In that case, we can help.

 
I never suggested he did, but rather am taking issue with the conceptualization he used to derive his equation. Again, the potential energy of the system in question is not relative to the whole of the mass of the tower suspended at the maximum height of the tower. Dividing that value by 3 does nothing to change that.

Dividing the height by 3 does nothing to change the height?

:jaw-dropp

ETA: That's it. I'm calling TROLL!
 
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Your completely unsubstantiated denials demonstrate the lack of sold ground from which you argue. Again, it seems rather obvious at this point that you've just got your empty hand in your pocket, waving it around trying to pretend like you have something there.
Fail.

I'm not the one who thinks a cow is just like an ant, only bigger and goes moo.
 
Sure, like if you stack 80 glass coffee tables on top of each other and then drop a bowling ball on that; once it starts, it's all over, eh? Assuming 10mm glass with a 1 kg/mm/mm tensile strength spaced 500mm apart, and a 10 kg ball with a 200mm diameter given say 100m over the top of the structure just for fun, how close to free fall would expect that ball to get after connecting with the first sheet of glass?

This is an easy problem to solve!

We have 80 glass elements of certain mass, m, spaced 500 mm apart. How the spacing is arranged must be clarified; some sort of supports I assume, the bottom one, carrying 80 m, stronger than the top one, carrying nothing but expecting to be impacted by a bowling ball.

Inertia is the name for the tendency of an object in motion to remain in motion, or an object at rest to remain at rest, unless acted upon by a force.

Thus, the tower of 80 glass elements/supports is at rest and the bowling ball comes dropping down in motion.

What happens at impact? Well, it depends on the strength of the top glass element and the bowling ball - the two elements in contact only! If the top element at rest is reinforced, armored glass and doesn't break, it will transmit forces on the supports below and on the bowling ball. The bowling ball may actually break or bounce or one or more supports below.

As we say: You have to start at the top to get things changed in a structure (or organisation).

In the example above, the 79 glass elements below the top one have not got a clue what the top glass element and bowling ball are up to, when they meet.
 

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