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8. The destruction of the South Tower in 10 seconds and of the North in 9 is even faster than free fall with only air resistance, which would have taken at least 12 seconds, which, as Judy Wood has emphasized, is an astounding result that would have been impossible without extremely powerful explosives.
Originally posted by jtma508
Freefall is the velocity achievable by an object (in a vacuum) that starts at zero velocity and whose subsequent velocity is entirely derived from the conversion of potential energy (gravity). Objects can achieve faster than freefall if kinetic energy is applied to them. For example, imagine you have two ball bearings sitting on slightly inclined platforms in identical vertical vacuum tubes. For one you remove its stop and let it fall. For the other you have a pinball machine like plunger to launch it. Which ball will fall the faster?
Originally posted by jtma508
For the other you have a pinball machine like plunger to launch it. Which ball will fall the faster?
In the course of its Investigation into the collapse of the World Trade Center Towers, NIST has not found any evidence that well-tied buildings performed unfavorably (or collapse earlier) than buildings that are not well-tied. In fact NIST has found that, had the major structural subsystems of the WTC towers not been tied together, the core of the towers would have collapsed earlier. The hat-truss tied the core to the perimeter walls of the towers, and thus allowed the building to withstand the effects of the aircraft impact and subsequent fires for a much longer time enabling large numbers of building occupants to evacuate safely.
Originally posted by Byrd
A lot of these claims rest on things that "someone said" but for which there is no objective evidence (or there's doctored evidence.) I heard one today, about a "cordite smell" at the Pentagon and immediately wondered "who said there was one" and "just where was this person" and "do we have proof of that person's presence" and "can they demonstrate they know what cordite smell is and can distinguish it from other smells."
As someone has said of these, the whole "conspiracy" relies on the emergency workers and rescue workers and police officers who were there ALL tacitly agreeing to the death and injury of so many members of their profession and callously covering up evidence of this. If you know any firefighters (I know several) or cops (I know several), you'll know just how unlikely a scenario this is.
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).
As documented in Section 6.14.4 of NIST NCSTAR 1, these collapse times show that:
“… the structure below the level of collapse initiation offered minimal resistance to the falling building mass at and above the impact zone. The potential energy released by the downward movement of the large building mass far exceeded the capacity of the intact structure below to absorb that energy through energy of deformation.
Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in free fall, as seen in videos. As the stories below sequentially failed, the falling mass increased, further increasing the demand on the floors below, which were unable to arrest the moving mass.”
In other words, the momentum (which equals mass times velocity) of the 12 to 28 stories (WTC 1 and WTC 2, respectively) falling on the supporting structure below (which was designed to support only the static weight of the floors above and not any dynamic effects due to the downward momentum) so greatly exceeded the strength capacity of the structure below that it (the structure below) was unable to stop or even to slow the falling mass. The downward momentum felt by each successive lower floor was even larger due to the increasing mass.
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.
In order for the tower to have collapsed "gravitationally", as we've been told over and over again, in the observed duration, one or more of the following zany-sounding conditions must have been met:
* The undamaged floors below the impact zone offered zero resistance to the collapse
* The glass and concrete spontaneously disintegrated without any expenditure of energy
* On 9/11, gravity was much stronger than gravity
* On 9/11, energy was not conserved
Originally posted by mecheng
Which brings me to my question: How is it possible to fall faster than free fall?
Also, on a related point, how is the exact and ending point at which the structure has fully collapsed determined with the amount of debris floating around? Is there a clear view of when the collapse has been completed?
Originally posted by Pepperslappy
I have to say though. If the building collapsed on itself wouldnt the vellocity not be constant?
Originally posted by bsbray11
Originally posted by Pepperslappy
I have to say though. If the building collapsed on itself wouldnt the vellocity not be constant?
EXACTLY.
It should have slowed down or sped up or something. People who think the mass simply built up more and more should have be wondering why there wasn't positive acceleration. People who know better and realize that 80+% of the masses were ejected out of the footprints should be wondering why they did not slow down as the resistance increased.
Either way, work is being done. The initial falling mass only had so much potential energy, and it was working upon a body that was provided (or SHOULD have been providing) constant resistance for every column, truss, bolt, concrete, chair, computer monitor, etc. that was resting down through the buildings. Why then, considering the mass did NOT increase in some linear 1 + 1 + 1 fashion, do we see the collapses hurtling downwards at a smooth, unrelenting pace, so easily and uniform?