WTC: Rate of Fall (rate of crush)

MikeC

Closed Account
This is because of the continued elastic deflection experienced in the lower section by the presumed impact of the top block before it enters the plastic phase. As you correctly stated earlier, this is more complicated than just a bunch of blocks hitting each other. ie steel has phases of elastic, shortening, and then plastic stages of deformation.
All of which can be passed through in a fraction of a second given an appropriate load and so would not be noticeable at all "by eye".

your maths doesn't seem to address the actual loading and time taken to fracture?
 

gerrycan

Banned
Banned
All of which can be passed through in a fraction of a second given an appropriate load and so would not be noticeable at all "by eye".

your maths doesn't seem to address the actual loading and time taken to fracture?
It is more about the energy balance in the system. The loss in KE works out at 66%, and that is really what is relevant here. As far as time taken goes, and loading, what exactly is it that you are looking for. Is it the time taken for the propagation wave to travel through the structure? Because i agree this would be very fast indeed. Or is it the actual time taken for the steel to go through its 3 phases of distortion and break?
 

gerrycan

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Banned
Where does it work out? I've yet to see this working. Preferably with a diagram.
The reduction in the velocity from 8.5 to 4.8m/s with the additional mass of the extra floor @ 4.8m/s comes out at 66%, so of the 2.1GJ avaliable at the start there would be 714MJ after the impact. And this is weighting things in favour of the gravitational theory. Do you not agree that we should have seen a deceleration in the collapse as opposed to a constant acceleration?
 

tjohnson_nb

New Member
All of which can be passed through in a fraction of a second given an appropriate load and so would not be noticeable at all "by eye".
"By eye" it looks like the bottom of the building disappeared as the top fell. The maths say this is impossible.
 

Mick West

Administrator
Staff member
The reduction in the velocity from 8.5 to 4.8m/s with the additional mass of the extra floor @ 4.8m/s comes out at 66%, so of the 2.1GJ avaliable at the start there would be 714MJ after the impact. And this is weighting things in favour of the gravitational theory. Do you not agree that we should have seen a deceleration in the collapse as opposed to a constant acceleration?
No, because A) your figures seem to be pulled out of thin air. 4.8? And B) the usage of KE was not instantaneous.
 

MikeC

Closed Account
"By eye" it looks like the bottom of the building disappeared as the top fell. The maths say this is impossible.
Only if you presume that the bottom collapsing was caused by the top collapsing.

but AFAIK we know that it was the interior collapsing that caused the exterior to collapse, so there seems to me no particular reason why the simultaneous collapse of various parts of the exterior could not occur.
 

gerrycan

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Banned
No, because A) your figures seem to be pulled out of thin air. 4.8? And B) the usage of KE was not instantaneous.
ok, as previously stated -
16 storeys @ 58000 tonnes fall for a floor at total freefall is (58000000/2)*(8.52*8.52) = 72.5904*29000000=2105121600J = 2.1GJ at impact.
Energy Losses -
17 storeys V2 m/sec + 1 storey moving at 23/24*V2 m/sec+ 1 storey @ 22/24*V2m/sec +......+ 1 storey moving at 2/24*V2 m/sec + 1 storeymoving at 1/24*V2m/sec 16*8.5 = V2 (17 + 11.5) so V2 i= 16 * 8.5 / 28.5 = 4.8m/s

the point in the above is that the lower storeys would have to shorten by 3% and that 16 storeys would deflect equally to the buckling load. You seem to be assuming that the colliison is inelastic, and as for plucking anything out of the air.....The only thing being plucked out of the air here is 3.7m worth of the tower, to allow the upper block to reach 8.5m/s in 3.7m of drop at g, which is giving your gravitational collapse theory a massive head start, and it still doesn't work. You need to show some figures of your own to justify you assertions that are not supported by NIST, who failed to address the actual collapse. Maybe you could use bazants paper, but you will find that he also has to assume that 3.7m worth of tower disappears into thin air. At least NIST had the sense not to try to address this.

What bit of the 4.8m/s calculation do you object to specifically?
 

Cairenn

Senior Member.
Not just a fire, but an uncontrollable fire coupled with structural damage and and explosion. Do you have another building that had all of those happen to it?
 

Mick West

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Staff member
So you claim that after the first impact then the first impacted floor is moving at 23/24, and the floor below that at 22/24, etc?

What then happens after that? And when does it happen?
 

gerrycan

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Banned
So you claim that after the first impact then the first impacted floor is moving at 23/24, and the floor below that at 22/24, etc?

What then happens after that? And when does it happen?
The collapse is arrested as it does not have enough momentum to overcome the resistance of the remaining lower block. As to what happens after that, i would guess that the 22 degree tip observed would come into play, but to be honest, i would be guessing. What this does show is that the upper block of the tower should not continue to accelerate through the rest of the structure.
Again, even if you don't agree that the collapse should have been arrested,do you agree that the collapse should at least have slowed down?
 

Mick West

Administrator
Staff member
The collapse is arrested as it does not have enough momentum to overcome the resistance of the remaining lower block. As to what happens after that, i would guess that the 22 degree tip observed would come into play, but to be honest, i would be guessing. What this does show is that the upper block of the tower should not continue to accelerate through the rest of the structure.
Again, even if you don't agree that the collapse should have been arrested,do you agree that the collapse should at least have slowed down?
I'm still trying to figure out your theory. You say after the first "impact" is speeds up the 24 floors beneath, to varying amounts (23/24, 22/24 ... 1/24 V2)? So before you've got 17 floors moving at V, and now you've got 41 floors moving? 17 at V2, and 24 at an average of V2/2? And then it just stops?

How exactly does it stop?
 

gerrycan

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Banned
I'm still trying to figure out your theory. You say after the first "impact" is speeds up the 24 floors beneath, to varying amounts (23/24, 22/24 ... 1/24 V2)? So before you've got 17 floors moving at V, and now you've got 41 floors moving? 17 at V2, and 24 at an average of V2/2? And then it just stops?

How exactly does it stop?
Abruptly.

"To shorten the columns of the first impacted storey by 3%, sufficient to complete the plastic shortening phase, a distance of about 0.111 metres, and allowing a constant speed of 8.5 metres per second, would take a minimum of 0.013 seconds....The propagation wave of the impact force would therefore travel a distance of 58.7 metres in a
time of 0.013 seconds. This means that during the time taken in the plastic shortening of the impacted columns, the same force would be felt at a minimum distance of 58.7 metres, or approximately 16 storeys, from the impact. These storeys would thus suffer an elastic deflection in response to, and proportional to, the failure load applied
at the impacted floor. These deflections would themselves take time and allow the propagation wave to move further downwards again affecting more storeys"
Mr G Ross, a fellow scotsman, puts it better than i ever could.
 

gerrycan

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Banned
Seems to ignore buckling failure.
There's a paper here http://rethink911.org/wp-content/uploads/2013/07/Szuladzinski.Johns_.Szamboti.pdf
that is quite recent that goes into quite a lot of detail as to why Eulers is misused re buckling. I tend to think that Gordon addressed the failure mechanism of the steel quite well, but perhaps didn't go into the kind of detail about that Tony et al do. Also worth mentioning again, that both Gordons paper and Bazants both presume total freefall for 3.7m in the top block, which is unrealistic, but favours a gravitationally driven collapse theory. I will hunt out a link to bazants paper if you need it.
 

Boston

Active Member
The mass of the building makes no difference to his calculations. He says that when the falling block is in contact with the building, then the building exerts an upwards force equal to the downwards force. This is correct. It's like if you place one brick on top of a pile of nine bricks, it's in equilibrium, the forces are balanced.

He then says that the upped block exerts a downwards force of ma (mass times acceleration, really should be mg, but it's the same thing). He then says the lower block exerts (or rather is capable of exerting, otherwise he's saying the top of the building should float away) an upwards force of (ma + the mass of the people + some safety factor). This is also true. The lower block is normally capable of supporting the weight building above it plus quite a bit extra. The bottom floors are capable of supporting the entire weight of the building, plus more. In fact, if his logic was correct, the upper block would slow down and stop after just a few floors.

Where he is wrong is in describing this upwards force as a constant force. It's not. gravity is a constant force, accelerating downwards. The upwards force only happens DURING CONTACT. When the upper block fall onto the lower block, there's a collision, the floor fails, and the block continues to accelerate.

So the upwards force will only affect the acceleration WHILE THE FLOOR IS BEING DETACHED. i.e., only while the joints are failing. That failure only takes a fraction of a second. But to calculate the amount of upwards force under his assumptions, you'd need to know how long it takes the floor to fail when 38,000 tonnes are dropped on it.
Just started reading this thread but I see a fundamental error in this response. The way to think of a collapse is in terms of kinetic energy and equal and opposite reactions. The falling object strikes the entire structure bellow it. That structure is designed to resist this force, plus some safety margin, typically about 100% including wind, snow and occupancy loads. The week point will be at the buildings highest intact point due to the tapering of columns towards the top. So a large amount of energy is absorbed by any flex that occurs in the remaining intact areas. That expenditure of energy will result in a loss of speed in the falling mass, or masses as the collapsing segment will not all strike the area bellow at the same time. Simultaneously there will be some deflection in the falling mass as it attempt to follow the path of least resistance, there will also be some deflection at the weakest points in the remaining structure which will/may lead to catastrophic failure of individual members. These members, in the case of WTC towers can be seen to eject horizontally from the structure. An equal and opposite energy must be considered to both the falling mass above and the remaining structure bellow. There's a collision, the structure fails but the but the acceleration of the falling mass is deflected and diminished by the act of expending energy to damage otherwise intact components bellow it. The energy of the falling mass should have been either deflected laterally into the path of least resistance or gradually halted as the kinetic energy of it originally having only collapsed one or two stories was gradually expended on a building designed to handle likely 2x its expected loading. The collapse should have decelerated and/or destabilized into the path of least resistance.


When the upper block fall onto the lower block, there's a collision, the floor fails, and the block continues to accelerate. Actually the block should decelerate in direct proportion to the rate of energy transfer

So the upwards force will only affect the acceleration WHILE THE FLOOR IS BEING DETACHED. i.e., only while the joints are failing. That failure only takes a fraction of a second. But to calculate the amount of upwards force under his assumptions, you'd need to know how long it takes the floor to fail when 38,000 tonnes are dropped on it
Another fundamental flaw is the structural steel doesn't like to shatter, it bends, it actually bends a lot before it even begins to reach any critical point. This bending absorbs energy, which again must be subtracted from the kinetic energy of the falling debris. This fundamental error can be found in a huge number of arguments about the falling block hypothesis.

If we modify Jazzy's hypothesis with his Newtons swing we find that energies are dissipated in many directions but only under manufactured conditions does it travel through the path of most resistance. In Jazzy's model he'd have the energy going straight down through the structural steel and melting the base of each column. Not likely. But there is some truth to the principal he's misunderstanding. The energy does transfer, but not all of it goes into breaking a single bond at a time, just as not all of it would go in a single direction. Its transferred to the entire remaining structure, which will respond as its designed and spread that load out as much as possible and bending when the loads get to some critical stage. Somewhere in there something breaks. But what broke isn't the only resistive force involved. Shock loading and bending strain must also be considered along with the individual elements of catastrophic failure. IE each beam that gets broken away from the remaining structure and its energy of ejection (IE acceleration ) from a position of resistance to a position of less resistance.

In the end, no I'm not going to calculate out the exact numbers, I'd need a free month or two and a set of print which we all know aren't available. But the towers should never have reacted the way they did and completely collapsed. At worst some significant portion of the towers should have survived and at best I don't think fire or the damage they received should have been sufficient to cause any major collapse.
 

Jazzy

Closed Account
the massive steel core that somehow disintegrated along with the floors. Not very credible. What do you think was the reason for the disintegration of the steel core?
The fact that the towers both leaned and fell.

Eulers theory is what is being misapplied re the buckling. It is actually only valid for very slender columns, which the WTC 47 cores were not.
ALL the columns in each building were slender. NONE of the columns could stand on their own. Study up, kid.

The WTC tower columns had a slenderness ratio of their height divided by their width. ! : 250? WTC7 columns 1: 150? They seem pretty slender to me....

when you do a momentum transfer analysis of the top block colliding with the building below, even when you allow it to fall for one whole floor at freefall acceleration, the velocity almost halves after the first impact to just over 4.5m/s.
But it fell two floors.

How does 5% crush 95% and continue to accelerate while it does so. I have never had a decent answer to that question yet.
See below.

The question of how these towers managed to constantly accelerate through themselves averaging around 66% total freefall is indeed perplexing to anyone who has read a physics book. The law of conservation of momentum seems to have taken a day off on 9/11. Interesting topic
But we already know the towers didn't fall straight down. This would mean that individual pieces of the intact portion of the towers would have to resist momentarily the total momentum of the falling tops. That would be a fail every time, don't you think?

These are the weakest column rows that remain standing, whilst the strongest have already fallen. This should not happen in a gravitationally driven event.
The core columns were designed to take more than half the building loads: they were stronger.

16 storeys @ 58000 tonnes fall for a floor at total freefall is (58000000/2)*(8.52*8.52) = 72.5904*29000000=2105121600J = 2.1GJ at impact.
Energy Losses -
17 storeys V2 m/sec + 1 storey moving at 23/24*V2 m/sec+ 1 storey @ 22/24*V2m/sec +......+ 1 storey moving at 2/24*V2 m/sec + 1 storeymoving at 1/24*V2m/sec 16*8.5 = V2 (17 + 11.5) so V2 i= 16 * 8.5 / 28.5 = 4.8m/s
Now calculate this for a two-story drop.

I meant to add that the Eulers theory thing about buckling load only applying to slender columns is explained very well here http://rethink911.org/wp-content/uploads/2013/07/Szuladzinski.Johns_.Szamboti.pdf
ALL the columns in every building were slender. NONE of the columns could stand on their own. Study up, kid.

this is more complicated than just a bunch of blocks hitting each other. ie steel has phases of elastic, shortening, and then plastic stages of deformation.
It was more complicated because the top LEANED, meaning it had access to the core support bracing, seen to be absent when the remaining core columns buckled and collapsed.

What this does prove is that the theory proffered by NIST is flawed
To the unobservant.

it is worth remembering that we are presuming that a whole floor (3.7m) of the tower just disappears and allows the block to drop at g.
Which means the top dropped TWO floors and twenty-four feet. Why did you say "one floor", when obviously you meant two?

It proves that there should be a more thorough investigation into the whole event.
You should indeed investigate more thoroughly.

The fact that controlled demolition was not considered in the report is counter-intuitive
It wasn't considered because the collapse timeline showed a progression of events preceding collapse, such as increasing sagging and bulging of the overall structure, and the collapsing of supporting floors, prior to collapse.

as this is the only cause ever of high rise steel framed building collapses like these. Fire does not have form for doing this to buildings made of steel, so the fact that NIST discarded the most likely cause, but clung to the least likely historically speaking should be a red flag to anyone. The implication that every highrise on the planet is now liable to collapse from fire should be disturbing to us all, whether it is true or not.
Doesn't make any sense...? LOL.

High-rise buildings are disturbing, full stop. R/C ones are obviously safer, with the steel inside the concrete.
 
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Dan Wilson

Senior Member.
16 storeys @ 58000 tonnes fall for a floor at total freefall is (58000000/2)*(8.52*8.52) = 72.5904*29000000=2105121600J = 2.1GJ at impact.
Energy Losses -
17 storeys V2 m/sec + 1 storey moving at 23/24*V2 m/sec+ 1 storey @ 22/24*V2m/sec +......+ 1 storey moving at 2/24*V2 m/sec + 1 storeymoving at 1/24*V2m/sec 16*8.5 = V2 (17 + 11.5) so V2 i= 16 * 8.5 / 28.5 = 4.8m/s
So when we have a mathematical demonstration like this, assuming it checks out, in this context we could do one of two things. Either perform experiments to test the equation or look for evidence of another mechanism (controlled demolition). Math alone doesn't prove anything, what is observed in nature has the final say. Since there was no evidence of explosives found at ground zero, your math and subsequent hypothesis doesn't support what was observed. The point is, take it a couple steps further and test it with a model or find some evidence for use of explosives.
 

Mick West

Administrator
Staff member
The energy of the falling mass should have been either deflected laterally into the path of least resistance or gradually halted as the kinetic energy of it originally having only collapsed one or two stories was gradually expended on a building designed to handle likely 2x its expected loading.
How many times the expected loading was 17 stories dropping on it?

 

Boston

Active Member
So when we have a mathematical demonstration like this, assuming it checks out, in this context we could do one of two things. Either perform experiments to test the equation or look for evidence of another mechanism (controlled demolition). Math alone doesn't prove anything, what is observed in nature has the final say. Since there was no evidence of explosives found at ground zero, your math and subsequent hypothesis doesn't support what was observed. The point is, take it a couple steps further and test it with a model or find some evidence for use of explosives.
Math basically proves or disproves everything, its like the perfect language. If it works mathematically, then it works. The only real problem is some folks have a hard time grasping that. Its the driving force behind the basic physics involved.

Oh and another wildly inaccurate model. This is getting to be a trend. Now show us one that accurately depicts what actually happened on 9/11. Say a mass 0.1545 that of the remaining structure and only falling 1/110 the total height. o_O Then go figure out the max design limit of the towers vs the actual loading and you begin to see the real picture. Oh and its not free fall, or at least not unless you instantaneously remove all resistance :rolleyes: How'd that happen :D
 
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Mick West

Administrator
Staff member
Oh and another wildly inaccurate model. This is getting to be a trend. Now show us one that accurately depicts what actually happened on 9/11. Say a mass 0.1545 that of the remaining structure and only falling 1/110 the total height.
You mean like this?

Seems like there are two misconceptions here:

1) Scale.
2) Static v.s Dynamic load bearing.
 

Dan Wilson

Senior Member.
Math basically proves or disproves everything, its like the perfect language. If it works mathematically, then it works. The only real problem is some folks have a hard time grasping that. Its the driving force behind the basic physics involved.
Not necessarily. Theoretical physicists spend most of their time trying to make predictions using math and then experiments test those predictions. The predictions aren't always right and it's usually because of something not accounted for in the equation. The only way you know for sure that your mathematical model works is to test it. It is a beautiful language but if it fails to translate into real world results it is meaningless.
 

Boston

Active Member
You mean like this?

Seems like there are two misconceptions here:

1) Scale.
2) Static v.s Dynamic load bearing.
I can't speak to the issues others might present when searching for accurate depictions of the physics involved. So I'm hesitant to assume any responsibility for the arguments of others.
 

Boston

Active Member
Not necessarily. Theoretical physicists spend most of their time trying to make predictions using math and then experiments test those predictions. The predictions aren't always right and it's usually because of something not accounted for in the equation. The only way you know for sure that your mathematical model works is to test it. It is a beautiful language but if it fails to translate into real world results it is meaningless.
True, but I wasn't implying it always works mathematically ;-) Just that if it does, its pretty much a done deal.
 

Jazzy

Closed Account
Seems like there are two misconceptions here: 1) Scale, 2) Static v.s Dynamic load bearing.
Clownish to an engineer, and if that guy's an engineer he's a total fraud.

Not necessarily. Theoretical physicists spend most of their time trying to make predictions using math and then experiments test those predictions. The predictions aren't always right and it's usually because of something not accounted for in the equation. The only way you know for sure that your mathematical model works is to test it. It is a beautiful language but if it fails to translate into real world results it is meaningless.
Surely the test in this case is the video evidence. If the model runs in the same detail and to the same timeline as the video evidence you're getting close.

In spite of the truthers' utter denialism, the model of the WTC7 collapse is remarkably similar to to the videos.

But what do I know? I'm merely an engineer who would have given his eye teeth for such modeling software round about, er, 1970, who frequented electronics shops looking at 8-bit computing in the mid-70's, bought a BBC Micro in 1981 (so that I could design postage stamps), and finally afforded an IBM PC round about 1995, although I did work on boosted ones ten years previously (which cost 50,000 quid) while working for someone else.

Boosted, yes. Doing? Very large office buildings. The Barbican and Little Britain. Not designing them, but cleaning them up, making them work properly, making contract documentation, tidying them up in general.

So this stuff is familiar to me.
 

Boston

Active Member
In spite of the truthers' utter denialism, the model of the WTC7 collapse is remarkably similar to to the videos.
I know I should be at least trying to maintain a straight face but really, "remarkably similar"

Who in the world are you trying to fool ? Neither NIST model in any way reproduced the collapse accurately. all anyone needs do is look at the model simulations side by side with the video evidence to see this for themselves. Unless that is, as you say, they are in a state of denial :rolleyes:

 
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Mick West

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Staff member
It quite close enough, if you consider the things that actually matter.

But this is off topic.
 

Jazzy

Closed Account
The loss in KE works out at 66%, and that is really what is relevant here.
The rate of acceleration towards the ground was .67G, so the LOSS in KE was 33%.

the actual time taken for the steel to go through its 3 phases of distortion and break?
Would not be noticeable. You should take at least ONE look at a vertical column buckling experiment. Otherwise you might end up talking b------t. Oh.

reduction in the velocity from 8.5 to 4.8m/s with the additional mass of the extra floor @ 4.8m/s comes out at 66%, so of the 2.1GJ avaliable at the start there would be 714MJ after the impact
Is, er, incorrect.

And this is weighting things in favour of the gravitational theory.
Hardly. You are pretending these towers are falling vertically down - again.


Do you not agree that we should have seen a deceleration in the collapse as opposed to a constant acceleration?
I accept the universally-accepted deceleration of 0.67G. Why don't you?

The collapse is arrested as it does not have enough momentum to overcome the resistance of the remaining lower block. As to what happens after that, i would guess that the 22 degree tip observed would come into play, but to be honest, i would be guessing. What this does show is that the upper block of the tower should not continue to accelerate through the rest of the structure.
I think everyone can see you are, er, incorrect.

Again, even if you don't agree that the collapse should have been arrested,do you agree that the collapse should at least have slowed down?
I'm sorry. I cannot be made to believe that black is white.

Just started reading this thread but I see a fundamental error in this response. The way to think of a collapse is in terms of kinetic energy and equal and opposite reactions. The falling object strikes the entire structure bellow it.

What?

That structure is designed to resist this force
What?

Another fundamental flaw is (that) structural steel bends. This bending absorbs energy, which again must be subtracted from the kinetic energy of the falling debris. This fundamental error can be found in a huge number of arguments about the falling block hypothesis.
Everyone accepts that something like thirty percent of the kinetic energy was being expended on the way down.

If we modify Jazzy's hypothesis with his Newtons swing we find that energies are dissipated in many directions but only under manufactured conditions does it travel through the path of most resistance.
The structure was the path of most resistance. It directly interposed itself between the building LOAD and gravity, as it was designed to do. But in its pre-collapse state it was leading, through its malformation, through its weakest link, to the path of LEAST resistance. You trap yourself with your jargon.

In Jazzy's model he'd have the energy going straight down through the structural steel and melting the base of each column.
Straw man, there.

There were TWO ROUTES for the deep transmission of heat energy.

The FIRST ROUTE was that EVERY column in the building suffered a succession of SHEAR EVENTS as each floor was detached from them. The REACTION to them would be at the column bases, which would suffer a HAMMER BLOW with each shear event.

The SECOND ROUTE would be the ARRIVAL of DETACHED STEEL at the wreckage pile, which by STEEL-TO-STEEL CONTACT would transfer the kinetic energy of the newly-arrived steel to the base of ground zero.

Not likely. But there is some truth <snip> less resistance.
Is so far off the mark there's no point in replying.

no I'm not going to calculate <snip> I don't think <snip> major collapse.
That's a relief.
 
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gerrycan

Banned
Banned
Okay, I am going to try and reply to this in a way that is not too condescending, tempting as it is to be so lol

The rate of acceleration towards the ground was .67G, so the LOSS in KE was 33%.
I agree, that is actually what happened, however the answer that I gave was dealing with what SHOULD have happened in the analysis of Bazant, who more or less wrote the official narrative, in a paper that tried to explain and justify how gravity could have done this. You have totally misunderstood this and need to go and reread what i said in that context if you wish to respond in an intelligent way. Interesting that when you work out freefall for a WTC tower it comes out to be 9.2s so 2/3 freefall would be 13.8. I think that this fits well with what is observable, and would query how NIST and others could get the collapse time so horribly wrong.

You then go on to state, when talking about the phases of distortion and buckling in a column..............
Hardly. You are pretending these towers are falling vertically down - again.
.
LOL Bazant is doing this, not me, I am merely stating his mistake. You need to show some figures for this, I have. If we need to deal with the conservation of angular momentum issue re the 22 degree tip observable in the North tower before it descends perhaps you should start another thread once you have read up on it.....Anyhow, meanwhile, back at the ranch.....You continue, re Bazants analysis...........

I'm sorry. I cannot be made to believe that black is white.


I share your disbelief re the official account that he presents, at last we have common ground lol. Did you attend the Dick Cheney school of markmanship? Hope the foot heals up soon lol.

Then you state.......





I accept the universally-accepted deceleration of 0.67G. Why don't you?
I accept that was what happened, I do not accept that it is what SHOULD HAVE happened in a gravitationally driven event, as per the figures I presented. Show your working please, and explain how the North tower experienced constant acceleration through itself.
I am happy to respond once you understand the context of what I am saying, even if you fail to grasp the basic concepts of physics involved, but let's not try to get into some measuring contest that is surplus to requirements please. It's tedious.
Remember, you are entitled to your own opinion, but not your own facts. Please try to stop confusing the 2.
 
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Oxymoron

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Banned
It quite close enough, if you consider the things that actually matter.

But this is off topic.
It looks very different to me, even on that cherry picked few seconds. Where does the actual bldg 7 start to twist in on itself as per the sim? That seems quite major but yep... off topic and 'people will see it their way', anyway.
 

Mick West

Administrator
Staff member
It looks very different to me, even on that cherry picked few seconds. Where does the actual bldg 7 start to twist in on itself as per the sim? That seems quite major but yep... off topic and 'people will see it their way', anyway.
It doesn't twist as dramatically as in the simulation, but that's not actually an important difference. What is important is all the things leading up to when the exterior started to collapsed.

There's too many variables and unknowns to accurately model the chaotic collapse. It's like simulating a break in pool. You could take a photo of a rack, measure the weight of all the balls, the coefficients of friction and restitution, the incoming position and velocity of the cue ball - and then plug it all into a simulation. But youa re not going to replicate what happened. You'll replicate the basics, some balls from the rack will scatter. But it's impossible to replicate where the ball will end up in a simulation, or even their initial trajectories.
 

Jazzy

Closed Account
in a way that is not too condescending
Your condescension is that of a worm to a thrush: A worm smells the thrush, thinks "i can't eat that". Meanwhile the thrush sees the worm and thinks "Yum!"

I agree, that is actually what happened
what SHOULD have happened in the analysis of Bazant, who more or less wrote the official narrative
Do you think I give a rat's ass about Bazant?

You have totally misunderstood this and need to go and reread what i said in that context if you wish to respond in an intelligent way
I haven't read Bazant. I made my analysis immediately I saw a plane strike a tower on September 11th 2001. I neither needed a Bazant, nor some "student of his" to make my analysis.

Interesting that when you work out freefall for a WTC tower it comes out to be 9.2s so 2/3 freefall would be 13.8.
I made it a little longer - about 0.7 seconds longer. It rather depends on when you believe "crush back" ceased.

You then go on to state, when talking about the phases of distortion and buckling in a column: "Hardly. You are pretending these towers are falling vertically down - again."
That's very interesting. Because I was responding to your: "And this is weighting things in favour of the gravitational theory". How and why would you make that mistake?

Bazant is doing this, not me, I am merely stating his mistake.
No. YOU are "doing it". Why would you re-state a "mistake"?

You need to show some figures for this, I have.
Figures for what?

If we need to deal with the conservation of angular momentum issue re the 22 degree tip observable in the North tower before it descends perhaps you should start another thread once you have read up on it
I don't need to read up on anyone, either to calculate the gain in angular momentum, or to know how that momentum was lost. I am not some myopic cave-dweller engaging in effing semantics.

Anyhow, meanwhile, back at the ranch.....You continue, re Bazants analysis...
No. I don't. My analysis had taken place by the end of that day. I was already fully aware of the manner in which the towers were constructed

I share <snip> lol.
A commonality with all the "truthers" I've ever had the misfortune to meet.

Then you state: "I accept the universally-accepted deceleration of 0.67G. Why don't you?" I accept that was what happened, I do not accept that it is what SHOULD HAVE happened in a gravitationally driven event, as per the figures I presented. Show your working please, and explain how the North tower experienced constant acceleration through itself.
That's a gap in which you are happy to stand, I'm sure. What you are asking for is that I should tell you what is happening at this moment:

Do you feel comfortable with this demand? Doesn't it leave you with a sense of:

?

I am happy to respond once you understand the context of what I am saying, even if you fail to grasp the basic concepts of physics involved, but let's not try to get into some measuring contest that is surplus to requirements please. It's tedious. Remember, you are entitled to your own opinion, but not your own facts. Please try to stop confusing the 2.
That's some fighting talk for a person who avoided answering:
"But it fell two floors."
"Individual pieces of the intact portion of the towers would have to resist momentarily the total momentum of the falling tops. That would be a fail every time, don't you think?"
"The core columns were designed to take more than half the building loads: they were stronger."
"The top LEANED, meaning it had access to the core support bracing, seen to be absent when the remaining core columns buckled and collapsed."
"Why did you say "one floor", when obviously you meant two?"
"The collapse timeline showed a progression of events preceding collapse, such as increasing sagging and bulging of the overall structure, and the collapsing of supporting floors".

That's not counting the questions and statements you have been evading on the other thread.

So, just in case you feel like avoiding more, shall I restate what's in this post too?

It looks very different to me, even on that cherry picked few seconds. Where does the actual bldg 7 start to twist in on itself as per the sim? That seems quite major but yep... off topic and 'people will see it their way, anyway.
You too need to consider how unpredictable impact, fire and collapse really are.

Also, if you study the still pictures of the collapsed WTC7 you can see where it twisted.
 
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