Kikapu:
Yes of course the top part of the buildings at Twin Towers above where the impact of the planes took place did collapse bottom up, because the structure gave way beneath it, hence triggering the bottom up effect for a second or two before the whole top part of the building compacting the floors below, creating a chain reaction of top to bottom collapse of the Towers.
I am sorry but the act of compacting floors requires energy. Kinetic energy – if you take energy out to compact floors and destroy steel columns, tie beams, even the light concrete floors, then the collapse would slow down .... again Newtons Laws of motion! It didn’t slow.... it continued to accelerate at almost free fall speed taking out the core columns right down to the basement all of which which were virtually undamaged.
The pancake theory, which you are explaining was discarded very quickly. There appears from all the videos that there was no resistance to the fall of the structures which would be so if it was one floor collapsing on the next .... and so on.
Look, this is very easy to explain. The tower that got hit second, collapsed first and the tower that got hit first, collapsed second. WHY?
I don’t know about easy but I tend to agree with that as a simplistic explanation.
Because the tower that got hit second, got hit at much lower level than the the tower that got hit first. All things being equal with the damage caused by the planes and the fire that followed, the tower that got hit second collapsed first because it had far more weight to support than the tower that got hit first, which caused the tower that got hit second to collapse first.
Again I agree to a point. You mention ‘
weight’ and that is a static concept not a dynamic concept. The millisecond the structure started moving, what happened was governed by Newtow’s Laws of motion and what we are told conflicts with two of them!
Why did the top ten floors not tumble toward the weakest side of the building and topple over? Newton says that motion will always be in the direction of least resistance! The hundred stories below that point were completely undamaged and designed to hold the weight of the whole tower. The tough bit was the central steel core, the outer shell was little more than a corrugated steel tube tied to the inner core with the lattice floor beams. The floors were in the main light concrete poured onto light galvanised corrugated steel sheets. (
Light concrete is around 20% by volume, air)
The impact obviously did not do enough damage to cause the collapse of the top section and it has been proved over and over again that 1) within maybe 2 minutes of impact the jet fuel was not the source of the fire. Much of it went straight through the structure to erupt as a ball of flame on the other side. 2) Liquid is heavier than air ..... any liquid fuel would head south through the central column and we know it did that because lifts came down full of charred bodies (
according to Fire Fighters in the lobby at the time).
So what melted the steel columns? The office furniture fires started by the impact would have had insufficient heat generated to melt steel. So the columns didn’t melt, so let’s consider they got hot, softened and then bent ...... which way would they bend? In the direction of least resistance i.e. they would have toppled toward the open wound in the building on the side of impact, just as Newton predicts! I didn’t.
With the South tower the impact, which was filmed by dozens of film crews, was across a corner. Very few of the central columns would have suffered anything other than fairly light damage as it was hit by the wing tip of the aircraft. Other than that the same things happened ..... much of the fuel went up in an external fire ball, and after that after a very short time the fuel ceased to have any effect, it was furniture/partitions/carpets etc. that fed the fires. Supported by video of survivor standing the aperture left by the aircraft waving to be rescued, if it had been hot enough around there to melt of even soften steel. That would have been impossible.
Why did it not topple? Same arguments apply, in fact even more so because of the mass it was supporting as a static load. Directly it moved .... bingo .... it has to follow the line of least resistance! It it went straight down as we saw, then that was the line of least resistance so what happened to the 47 steel column core structure? In both cases, to destroy that would take energy. Transfer kinetic energy to remove the columns, rip out the floor beams and pulverise the light concrete and you slow the collapse .... in both cases it didn’t slow, it continued to drop at almost free fall acceleration.
If we are to believe any "controlled demolition" theories on the Twin Towers, why not demolish the towers in the order they were hit. That would make sense, No?
Looked at simplistically and disregarding any other factors , it would make some sense. The order of collapse, i.e.which went first, is really irrelevant as it would also depend on the extent of the damage to the structure and looked at, the North Tower, which was the second to go down would have sustained much more structural damage than the South tower as it took a head on impact covering almost the whole core structure.
This is not advanced engineering .......... it is basic GCE physics and common sense!
