Don't you see that, as I explained above in another post, if the floor of the upper block does not get lifted from its seats then you now have the entire mass of the upper block on the first lower floor. If it does then the columns continue downward carrying to our as yet unfailed level, another floor, and another,,,(repeat up to at least ten times)
You are now reduced to argueing how many floor masses it would take to fail one floor. In addition there is of course, the dynamic loading which you are attemptinmg to minimize yet it is still there. Further, of course, if this is more than one floor we simply cannot expect that the perimeter and core columns are sliding straight down the same hole they opened up as they speared downward at the initiation of collapse. They are tearing away more of that originally impacted flooring not to mention that they weakened the floor pan when they punched through in the first place. They are also doing a number on floors lower down.
You, and your mentor, seem to believe that the floor pan can by some magical physics, support the entire upper block. Heiwa has attempted to say that the material will get wedged between the core and perimeter. B.$. pure and simple. How can that possibly transfer the mass load of the block to the columns and not push the perimeter columns outward, snapping their seats to the trusses?
It is mostly instantaneous, but it is declaration regardless.
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Any deccelleration that the falling mass experiences must, in order to arrest the collapse, reduce the impact at the next lower floor.
How can it do so. Well it cannot do so by reducing the velocity of the falling mass as that falling mass will again experience the same accelleration falling between the first failure floor and the next. Therefore even if velocity was reduced to zero before the first floor failed the falling mass would acheive that same impact velocity again when it hits the next lower floor.
Obviously in the case of the towers the initial impact did not reduce the velocity of the falling mass to zero and thus the velocity of the mass falling on the next lower floor was even greater than the first.
Yes, impact force is the transfer of momentum divided by the duration time of impact. That is why a container of sand produces greater impact that a slowly poured bucket of sand. The very first impact of floor on floor occured with largely intact floors so this is not a bucket of sand, rather it is a load of large rocks by analogy.
1) This is sufficient to snap or buckle the majority, if not all, of the truss seats on the lower block's floor and lift the upper block floor from its seats. Now the combined mass of the upper and lower block floors are heading downward and will impact the next lower floor at a higher velocity than the first impact due to the fact that the upper floor was already moving. The transfer of monentum would have seen the velocity of the combined mass of the two floors being less than a free fall object BUT the columns are still spearing downward through more floors AND the next intact upper block floor is coming down at the same acelleration of the rest of the upper block (which is what we see from outside). This next upper block floor would eventually catch up to the combined mass of the other two floors since it has yet to be involved in a transfer of momentum.
Thus you have a situation in which the collapse will not arrest as each floor gets hit by a mass of greater velocity and greater mass than the one above it. The slowing of the transfer of momentum by the break up of the debris is small compared to the gain in momentum due to the acceration due to gravity and the increse in falling mass.
2)The first impact is not sufficient to break the truss seats. It holds against the impact of the two floors and is hit half a second later by yet another floor of essentially equal mass but which has been falling for 30-50% longer and thus is moving even faster than the first impact. This floor is likely more intact and hitting as a solid object more so than the first impact. So we have less effect of a slowing of transfer of momentum.
It would be difficult to imagine that this lower block floor, significantly damaged by the spearing through of the columns of the upper block, would resist this second impact but even if it does it is followed by yet another one after a still shorter interval and at a yet higher velocity, and again ,, and again,,,,,
In this case the slowing of transfer of momentum by the break up of debris is less significant because each impact is occured at a faster velocity and with less of a time interval between impacts(which would disallow the resisting floor time to rebound). This floor will eventually succumb to the insults and the combined mass of however many floors you wish this to be will now impact the next lower floor followed quickly by yet another upper block floor. The rubble will at this time still contain large blocks rather than be 'sand'. It will also simply have a mass that would be a strain on one floor if it were all loaded onto a pristine intact WTC tower floorspace much less one that is already damaged (spearing columns)and loaded with this mass over a time of no more than three quarters of a second!
What is visible from the outside? Not the floor impacts, the dust and smoke expelled and the perimeter columns would obscure this. Instead all we can see is the perimeter columns above and below the dust/smoke cloud.
(note that we are speaking of the first few seconds here)
ETA
(because I cannot resist): I do declare!
I was a forest firefighter. When the waterbombers came in we stood well back. The water coming down easily snapped large branched off trees and would just as easily snap a neck on a hapless soul who lingered too long on the fire lijne with a load of water coming in.
