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Moderated Continuation - Why a one-way Crush down is not possible

aggle-rithm said:
My God....do you know what this means?

Isaac Newton was in on it!!!!

This dastardly conspiracy runs far deeper than we feared...
Click to expand...

Now I'm waiting for some letter to show up that reads: "To all those who are taking my theories seriously...Ha!ha!ha!..Psyched you out!" I. Newton.
 
tfk said:
Anders,


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Wow. All those words.

Hoping to bloviate away the blatant error in this statement:

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After your error has been pointed out to you about 5 times.

Anders, you REALLY should stop this nonsense. It's making you look silly.

Everyone here with any tech background knows what kinetic energy & momentum are. You can stop that nonsense.

Everyone here with any tech background, except you apparently, knows exactly what happened to the bicyclist's momentum. You are the only person asking "But are you really sure that the momentum of the bicyclist was transferred to the Earth affecting its momentum?"

The answer is "yes, the momentum is transferred to the earth". And no, it did not "become heat".

Everyone here with a tech background, except you apparently, understands that momentum is NOT turned into heat. By the simple, obvious proof that VECTORS (momentum) do not turn into SCALARS (heat).

Everyone here with a tech background, apparently you apparently, understand that kinetic energy (also a scalar) gets converted into heat (another scalar). And that this process does not "absorb" or "reduce" or "remove" momentum in the slightest.

But you'll simply keep posting meaningless words after meaningless words, ad infinitum, rather than say "Ooops, I blew it".

This does not help your credibility.

Tom
Click to expand...

Sorry, momentum is only conserved in a closed system when no external forces are applied.

Momentum is a conserved quantity, meaning that the total momentum of any closed system, one not affected by external forces, cannot change.

But no system is ever 'closed' in the real world. External forces are affecting the masses of any 'closed' system and the result is ... the momentum is not conserved. Quite basic, actually.

'Closed' systems exist only on paper to describe, e.g. solid mechanics problems and similar. Anyone suggesting WTC 1 or any collision between two bodies is a closed system doesn't know basic physics.
 
tfk said:
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I didn't say "overload the floor locally". I said "overload the entire floor". All of it. To about 600 psi. The answer is "the whole floor collapsed".

Related question... If the cross trusses are rated to carry 30 psi, with a FoS of 3, do you think that the brackets connecting the cross trusses to the columns would be designed with FoS of 20? If you do, you'd be wrong.

Now, what happens when the 600 psi rated loads, over the ENTIRE FLOOR, is applied to the bracket & supports that will also be rated to carry about 100 psi floor loading?

It collapses.
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To a high probability,

1. the concrete buckles & collapses at many, many locations.
2. the cross trusses do not break in the middle, but buckle in the middle.
3. when they buckle, they are pulled inward from the external columns & outward from the core columns, and fracture at one or both locations.
4. when the various cross trusses collapse, they do not "dump their contents out thru the window". This is purely ludicrous. In order to do this, the floor would still have to be intact after dropping and able of supporting the 600+ psf load. Those floors were neither intact nor able to support 600 psf.

If this idiocy were true, there would be little to no rubble WITHIN the footprint of the building. It would be left in giant rubble heaps from the edges of the building outward. Nothing like this was seen.
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Sure thing. 36' high columns that are stacked on top of each other and held together with 4 1" diameter bolts are going to be able to produce a 3, 6 or 9 story tall fence that will contain 50,000 tonnes of falling debris without bracing...

What did you say you did for a living?

Tom
Click to expand...

So you suggest that a complete floor was suddenly overloaded >600 psi and that then every connection holding the floor in position failed simultaneously and that the floor dropped - free fall, I assume?

But this is the start of the infamous 'pan cake' theory that is not valid.

The floor is 60 m square with a big hole, 20x30 m, in the middle (the core) and connected to columns at perimeter walls and core. Above the floor is 3.6 m of air and some loose items <2-3% of the total volume.

Sorry, no such element (a floor) can fail the way you suggest.
 
Tony Szamboti said:
The floors were capable of supporting 12 times their own weight. See question 1 in the NIST Dec. 2007 FAQ.

http://wtc.nist.gov/pubs/factsheets/faqs_12_2007.htm
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Here is the full quote.
The vertical capacity of the connections supporting an intact floor below the level of collapse was adequate to carry the load of 11 additional floors if the load was applied gradually and 6 additional floors if the load was applied suddenly (as was the case). Since the number of floors above the approximate floor of collapse initiation exceeded six in each WTC Tower (12 and 29 floors, respectively), the floors below the level of collapse initiation were unable to resist the suddenly applied gravitational load from the upper floors of the buildings.
Click to expand...

I have bolded the really important bit you missed out.
 
Tony Szamboti said:
The floors were capable of supporting 12 times their own weight. See question 1 in the NIST Dec. 2007 FAQ.

http://wtc.nist.gov/pubs/factsheets/faqs_12_2007.htm
Click to expand...

Tony
You inadvertently left out the subsequent sentences from the same quote:

"Since the dynamic amplification factor for a suddenly applied load is 2, an intact floor below the level of collapse initiation could not have supported more than six floors. Since the number of floors above the level where the collapse initiated, exceeded 6 for both towers (12 for WTC 1 and 29 for WTC 2), neither tower could have arrested the progression of collapse once collapse initiated. In reality, the highest intact floor was about three (WTC 2) to six (WTC 1) floors below the level of collapse initiation. Thus, more than the 12 to 29 floors reported above actually loaded the intact floor suddenly."


Also check out this thread OP to discover why you and David Chandler are wrong. Part 3 at the end of OP.

http://www.internationalskeptics.com/forums/showthread.php?t=150934
 
Last edited:
BasqueArch said:
Tony
You inadvertently left out the subsequent sentences from the same quote:

"Since the dynamic amplification factor for a suddenly applied load is 2, an intact floor below the level of collapse initiation could not have supported more than six floors. Since the number of floors above the level where the collapse initiated, exceeded 6 for both towers (12 for WTC 1 and 29 for WTC 2), neither tower could have arrested the progression of collapse once collapse initiated. In reality, the highest intact floor was about three (WTC 2) to six (WTC 1) floors below the level of collapse initiation. Thus, more than the 12 to 29 floors reported above actually loaded the intact floor suddenly."


Also check out this thread OP to discover why you and David Chandler are wrong. Part 3 at the end of OP.

http://www.internationalskeptics.com/forums/showthread.php?t=150934
Click to expand...

I didn't leave anything out, as I gave the link to the FAQ.
 
Heiwa said:
Sorry, momentum is only conserved in a closed system when no external forces are applied.

Momentum is a conserved quantity, meaning that the total momentum of any closed system, one not affected by external forces, cannot change.

But no system is ever 'closed' in the real world. External forces are affecting the masses of any 'closed' system and the result is ... the momentum is not conserved. Quite basic, actually.

'Closed' systems exist only on paper to describe, e.g. solid mechanics problems and similar. Anyone suggesting WTC 1 or any collision between two bodies is a closed system doesn't know basic physics.
Click to expand...
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Tell ya what.

Why don't you tell us what happened to the momentum of the bicyclist...

Please be complete.

Tom
 
stateofgrace said:
Here is the full quote.


I have bolded the really important bit you missed out.
Click to expand...

BasqueArch said:
Tony
You inadvertently left out the subsequent sentences from the same quote:

<snipped for brevity>

Also check out this thread OP to discover why you and David Chandler are wrong. Part 3 at the end of OP.

http://www.internationalskeptics.com/forums/showthread.php?t=150934
Click to expand...

I almost brought this point up, but it's technically not the right one. Szamboti's claim is based purely on the lunacy that there was no dynamic or eccentric load based on there being no visible "jolt." He leaves out the statement not to quote mine it, but instead because he sees the extra figure as irrelevant because he asserts it was never a factor to begin with... He's treating the collapse as if the building resisted the upper section as a unit, which it did not; at any point during the collapse.

I've posted this multiple times to show him wrong when he claimed that there was no evidence that the columns failed via buckling, and whenever he asserted that there was no evidence of eccentric loading. I think it does a fine job of explaining how the building reacted to having a multistory section move out of the vertical:

tilt.png


He's never actually answered to these. I even took the time to highlight it and he's oblivious to it... I personally don't care how many times I post it to no avail, I don't let easy mistakes like these don't go away. I will remind individuals like Heiwa and Tony however every single time to make this point clear.
 
Heiwa said:
Sorry, momentum is only conserved in a closed system when no external forces are applied.
Click to expand...

OK, then, let's take a look at the external forces applied. The starting point is that the kinetic energy of the upper block is sufficient to strain the lower block to the failure point; since energy = force x distance, this kinetic energy is therefore the integrated product of the force exerted by the upper block on the lower, multiplied by the distance through which it compresses the lower block. For the lower block to survive, you need to find some other force slowing the upper block - in other words, acting upwards - that isn't transmitted through the structure of the lower block, because the lower block is already strained beyond its failure point.

So where is this mysterious upward force coming from? Not gravity, for a start; even Heiwa dimly recognises that gravity acts downwards, though he seems a little unsure of the implications of that. Heiwa has suggested friction and entanglement, but that doesn't help his case; friction will simply transmit force to the lower block by a different means, and won't reduct the overall force at all. And entanglement isn't a force, as such; it's just a catch-all word Heiwa uses to suggest that the forces between the upper and lower block are a little more complicated than a simple end-on collision between columns. Fine, in reality that's most likely true; but again, these are simply other ways that the force can be transmitted to the lower structure.

So, Heiwa, where's your mysterious additional force coming from? It has to act through something other than the support columns of the lower block, because we've already accounted for their entire capacity to exert an upward force, and we know that isn't enough to stop the upper block.

Got any ideas?

Dave
 
Conservation of momentum

It seems everyone agrees that momentum is conserved in a 'closed' system. So what 'closed' system are we talking about? Upper part C alone? It is the allegedly moving assembly of elements, each with a mass, that, when displacing due to gravity, impacts lower part A, another assembly of elements with masses. Part C is evidently subject to external force - gravity - and its momentum is therefore increasing all the time during free fall until impact, BANG. So part C is not a 'closed' system.

At impact part A evidently applies new forces on part C - again modifying the momentum of part C.

Is part A a 'closed system'? Prior impact it was in static equilibrium and not moving at all. Its momentum was therefore zero. Why was part A not moving? Evidently becase it was attached to part E(arth)! Part E has almost infinite mass compared with parts A and C.

Are parts C and A together, after impact, a 'closed' system? Evidently not as part E applies an external force on it, i.e. on part A.

Are parts C, A and E a 'closed' system? Answer is no! Parts S(un) and M(oon) apply forces on it! A 'closed' system only exists to simplify, e.g. analysis of solid mechanics problems, where you just ignore external forces.

Anyone suggesting that part A is squeezed like a lemon between two bodies, parts C and E, due to gravity forces and conservation of momentum and pressed into a part B - rubble - has not understood basic physics.
 
tfk said:
.
Tell ya what.

Why don't you tell us what happened to the momentum of the bicyclist...

Please be complete.

Tom
Click to expand...

The momentum of the bicyclist was reduced to zero, when friction force was applied to the bicyclist.
 
Heiwa said:
It is the reaction force that part A applies on part C at impact (according to Newton 3).
Click to expand...

Wrong. The reaction force is a compressive force on the columns of part A, and we've already found that that force is great enough to collapse the columns of part A. Unless you can find an upward force on B and C that isn't transmitted through the columns of A, then collapse propagates.

Oh, and it has to be sufficiently large to be significant. The gravity of the Sun and the Moon won't do.

So, we've ruled out reaction force, entanglement and friction, because they're all transmitted through the columns. Any more suggestions?

Dave
 
Tony and Heiwa,

I have asked a quite civil question, which as been ignored maybe it was because it was not grammatically correct, so I will ask it again.

NIST as stated that the WTC’s floors could only support six floors when this weight is applied suddenly.

Can you please explain what will happen to a floor in the WTC when this dynamic weight is exceeded?

Thank you.
 
Dave Rogers said:
Wrong. The reaction force is a compressive force on the columns of part A, and we've already found that that force is great enough to collapse the columns of part A. Unless you can find an upward force on B and C that isn't transmitted through the columns of A, then collapse propagates.

Oh, and it has to be sufficiently large to be significant. The gravity of the Sun and the Moon won't do.

So, we've ruled out reaction force, entanglement and friction, because they're all transmitted through the columns. Any more suggestions?

Dave
Click to expand...

??? The reaction force is applied on part C by part A. That reaction force does nothing to part A (as A applies it on C). It only affects part C as per Newton 3. You, DR, really have to brush up your physics.
 
stateofgrace said:
Tony and Heiwa,

I have asked a quite civil question, which as been ignored maybe it was because it was not grammatically correct, so I will ask it again.

NIST as stated that the WTC’s floors could only support six floors when this weight is applied suddenly.

Can you please explain what will happen to a floor in the WTC when this dynamic weight is exceeded?

Thank you.
Click to expand...

I have done it several times, did you miss it? When a floor element in the WTC is overloaded for any reason, it - the element - or one of its connections to other elements fails. It is a local failure. It is step one in classical structural damage analysis. Step two is to find out what happens next.
 
Heiwa said:
??? The reaction force is applied on part C by part A. That reaction force does nothing to part A (as A applies it on C). It only affects part C as per Newton 3. You, DR, really have to brush up your physics.
Click to expand...

Pure, unadulterated BS. The reaction force is matched by a downward force on A; that is Newton's Third. The force exerted on A by C matches the force exerted on C by A. All the arresting forces you've suggested are matched by compressive forces on A, and we know that they're enough to collapse A. Unless you can come up with a force that wasn't transmitted through A - and it's impossible that you could - then you're simply blowing smoke.

Dave
 
Heiwa said:
So you suggest that a complete floor was suddenly overloaded >600 psi and that then every connection holding the floor in position failed simultaneously and that the floor dropped - free fall, I assume?

But this is the start of the infamous 'pan cake' theory that is not valid.

The floor is 60 m square with a big hole, 20x30 m, in the middle (the core) and connected to columns at perimeter walls and core. Above the floor is 3.6 m of air and some loose items <2-3% of the total volume.

Sorry, no such element (a floor) can fail the way you suggest.
Click to expand...

Is there a five-second rule, like the one used when you drop food on the ground, that tells each supporting column that it must wait a certain amount of time after one of its companions has failed, before it itself fails?

How does that work, exactly? What is the waiting period, and how is it determined? I would be interested to see your calculations.
 
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