tjohnson_nb
New Member
What it proves is that the building did not collapse due to gravity - you are free to speculate as to why it did collapse.Surely that proves deliberate demolition?
What it proves is that the building did not collapse due to gravity - you are free to speculate as to why it did collapse.Surely that proves deliberate demolition?
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?
It is more about the energy balance in the system. The loss in KE works out at 66%,
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?Where does it work out? I've yet to see this working. Preferably with a diagram.
"By eye" it looks like the bottom of the building disappeared as the top fell. The maths say this is impossible.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".
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?
"By eye" it looks like the bottom of the building disappeared as the top fell. The maths say this is impossible.
"By eye" it looks like the bottom of the building disappeared as the top fell. The maths say this is impossible.
ok, as previously stated -No, because A) your figures seem to be pulled out of thin air. 4.8? And B) the usage of KE was not instantaneous.
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?
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?
There's a paper here http://rethink911.org/wp-content/uploads/2013/07/Szuladzinski.Johns_.Szamboti.pdfSeems to ignore buckling failure.
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.
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
Seems to ignore buckling failure.
The fact that the towers both leaned and fell.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?
ALL the columns in each building were slender. NONE of the columns could stand on their own. Study up, kid.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.
But it fell two floors.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.
See below.How does 5% crush 95% and continue to accelerate while it does so. I have never had a decent answer to that question yet.
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?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
The core columns were designed to take more than half the building loads: they were stronger.These are the weakest column rows that remain standing, whilst the strongest have already fallen. This should not happen in a gravitationally driven event.
Now calculate this for a two-story drop.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
ALL the columns in every building were slender. NONE of the columns could stand on their own. Study up, kid.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
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.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.
To the unobservant.What this does prove is that the theory proffered by NIST is flawed
Which means the top dropped TWO floors and twenty-four feet. Why did you say "one floor", when obviously you meant two?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.
You should indeed investigate more thoroughly.It proves that there should be a more thorough investigation into the whole event.
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.The fact that controlled demolition was not considered in the report is counter-intuitive
Doesn't make any sense...? LOL.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.
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 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.
Here's a fairly good answer:How many times the expected loading was 17 stories dropping on it?
It does. It makes no difference, because 58,000 tons doing 19 mph couldn't be stopped even if it fell straight down, which it didn't.assuming it checks out
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.
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.
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.
You mean like this?
Seems like there are two misconceptions here:
1) Scale.
2) Static v.s Dynamic load bearing.
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.
Clownish to an engineer, and if that guy's an engineer he's a total fraud.Seems like there are two misconceptions here: 1) Scale, 2) Static v.s Dynamic load bearing.
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.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.
In spite of the truthers' utter denialism, the model of the WTC7 collapse is remarkably similar to to the videos.
The rate of acceleration towards the ground was .67G, so the LOSS in KE was 33%.The loss in KE works out at 66%, and that is really what is relevant here.
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.the actual time taken for the steel to go through its 3 phases of distortion and break?
Is, er, incorrect.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
Hardly. You are pretending these towers are falling vertically down - again.And this is weighting things in favour of the gravitational theory.
I accept the universally-accepted deceleration of 0.67G. Why don't you?Do you not agree that we should have seen a deceleration in the collapse as opposed to a constant acceleration?
I think everyone can see you are, er, incorrect.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'm sorry. I cannot be made to believe that black is white.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?
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
Everyone accepts that something like thirty percent of the kinetic energy was being expended on the way down.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.
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.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.
Straw man, there.In Jazzy's model he'd have the energy going straight down through the structural steel and melting the base of each column.
Is so far off the mark there's no point in replying.Not likely. But there is some truth <snip> less resistance.
That's a relief.no I'm not going to calculate <snip> I don't think <snip> major collapse.
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.The rate of acceleration towards the ground was .67G, so the LOSS in KE was 33%.
Hardly. You are pretending these towers are falling vertically down - again.
.
I'm sorry. I cannot be made to believe that black is white.
I accept the universally-accepted deceleration of 0.67G. Why don't you?
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.
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!"in a way that is not too condescending
I agree, that is actually what happened
Do you think I give a rat's ass about Bazant?what SHOULD have happened in the analysis of Bazant, who more or less wrote the official narrative
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.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 made it a little longer - about 0.7 seconds longer. It rather depends on when you believe "crush back" ceased.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.
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?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."
No. YOU are "doing it". Why would you re-state a "mistake"?Bazant is doing this, not me, I am merely stating his mistake.
Figures for what?You need to show some figures for this, I have.
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.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
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 constructedAnyhow, meanwhile, back at the ranch.....You continue, re Bazants analysis...
A commonality with all the "truthers" I've ever had the misfortune to meet.I share <snip> lol.
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: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 some fighting talk for a person who avoided answering: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.
You too need to consider how unpredictable impact, fire and collapse really are.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.