North Tower:
A Too Fast Collapse for
Gravitational Collapse
Theories

The free fall curve is here the curve of a freely falling apple in vacuum. But the fastest fall the laws of physics allow us to conceive for this tower even neglecting any resistances of the structure to the collapse is actually much slower than this apple free fall because at least the energy must be lost to set  the impacted  floors in motion which unavoidably results in a slowing down of the pile driver and must limit the acceleration at a maximum of 70% the free fall speed in the first 3 seconds. This is approximately the measured acceleration of the roof in the first three seconds so the roof is at the maximum conceivable acceleration.

After those three seconds, its much worse: we find that the front (head) of the destruction observed at t=7s is far ahead the fastest theoretical front
the laws of physics allow us to conceive, so it does not need to be faster than the apple free fall speed in vacuum (a very deceptive reference) to let us conclude that we are facing here a major physical impossibility ! Looking at the above curves we realize that the famous engineers supporting in there publication the gravitationnal collapse are not in position to contradict us since their own curves standing for their theoretical predictions lie well above the point of an observed massive ejection at t=7s at floor 58  (though considerable efforts were made to favour an as fast as possible collapse in this publication for instance the hypothesis that the efficiency for crushing and pulverizing concrete is almost 100% allowing a very small amount of energy to be enough to do the job) meaning a destruction front terribly slow as compared to the observed one. The idea that the ejections seen there are just air evacuated  from below sounds particularly ridiculous since these ejections are obviously massive and at the same time localized on one face of the tower!

Another crucial observation is that the acceleration of the base of the 12 floors pile driver is clearly much less than that of the measured roof one in the first seconds otherwise at t=3s the destruction front would have overtaken floor 92.  In other words, and as we could have anticipated, the upper pile can not be considered the rigid bloc the Official Theory supporters supposed
. This upper pile is at the contrary very soon reduced and compacted from below : it does not destroy the lower part of the tower without being crushed itself: evidence for crush up along with crush down from the very start of the collapse is thus obvious. Moreother the idea that the upper pile could destroy the lower pile without being itself destroyed and compacted is completely nonsense since the forces are the same on both sides (action and reaction principle): the top and bottom part of the pile driver must converge very soon and produce a very compact object.

We can easily show that this slowing down concerns at least the 6 lower floors of the upper pile reaching a maximum speed of 11m/s resulting in an at most 17.5m/s speed for the whole upper pile center of mass at t=3s in the hypothesis that all the other floors fell down at 0.7g, just as the roof from t=0 reaching 22m/s at t=3s.
According to our own simple algorithm which, as we could check, reproduces Bazant results when we otherwise adopt the same wrong hypothesis, such speed is very insufficient to allow the destruction to reach the level of the very massive and powerful  ejections : it will be 2.2 seconds late even neglecting any resistance of the tower and mass losses of the pile driver!   In other words, there is no way how the lost of time accumulated in the first seconds and slow velocity of the whole upper pile at t=3 seconds could be made up for in the subsequent phase of the collapse.
And yet we did not apply any resistance to the rest of the collapse as we could have done since we now know how the pile driver was decelerated in the first three seconds. Indeed this slow acceleration for the whole upper pile, which is much less than that of the roof, should apply to and slow down in the same way the following seconds of collapse (remember that the lower floors are even expected to be much more resistant since these were not weaken by a plane impact nor fires), for example between t=3s and t=7s: injecting such effect in the algorithm typically makes the collapse several seconds slower.
It can be shown that any other hypothesis concerning the starting upper pile leads to the same conclusions
: time and speed are lost in the first three seconds and floor 58 of the massive ejections cannot be reached intime.  Even making the non physical hypothesis that at t=3s the whole upper  pile has the speed of its roof (22 m/s) and neglecting any form of resistance of the tower, the conservation of momentum alone implies that the level of the massive ejections is not reached before t=7.4 s vs 7 observed !

Let us stress again that no pressure effect can eject tons of massive material tens of floors ahead a collapse on a single face of the tower since an overpressure of course must apply uniformly in an open structure as is a tower floor and all faces should be blown out in the same way: these are obviously explosive ejections!

Frederic Henry-couannier
Manfred Cochefert

Could the concrete be pulverised to 60 microns dust particles at WTC?

The average energy of one kilo of concrete at WTC was: 1x10x200 =2000 J. According to
Greening it could be pulverised to  60 microns dust because it only needed ~ 885 J/kg for that. Really?
The mechanical energy consumed by a 600 Watts drill is also almost entirely mechanically (good efficiency) produced. In 10 seconds : 6000 Joules. Can you pulverise your one kilo concrete with it in 10 seconds ? Try!
The mechanical energy consumed and mechanically produced by an impact crusher (which converts electrical energy into gravitational energy of the product in a big rotating drum) and needed to crush one kilo of concrete to 60 microns dust is ~ 80000 J (corresponding to 21kWh/ton).
So why are the WTC towers ~ two orders of magnitude more effective in crushing concrete than any machine optimized for that (drill, impact crusher...) according to
Greening ?!

Simply because Greening completely neglects the fact that when collisions occur most of the energy is converted into heat: this is true for the drill, the impact crusher, but also for the towers. In the case of the impact crusher, 2.7% only of the
80000 J are crushing, the rest is heating all mechanical parts of the machine and the concrete itself. 2.7% of 80000J = 2160 J, still somewhat greater than the 885 J/kg assumed by Greening for the WTC because the WTC concrete is a light one.
Why can Greening neglect the ridiculous efficiency of random collisions at WTC to produce crushing without anyone noticing that ?
Because his
885 J/kg are computed starting from the energy needed to fracturate concrete in traction (concrete is much less resistant in traction than in compression) and with 100% efficiency:  20 Joules per squared meter! How does he know that constraints in WTC random collisions were applied in traction with 100% efficiency ?
Conclusion: it is absolutely obvious that the energy that the towers could actually produce was orders of magnitude (i would say at least a factor 100) insufficient to pulverise the concrete to 60 microns. So why are even most truthers taking serious the Greening numbers in their balance?