CONT

Paul.L
Turning now to point 4, I draw your attention again to a paper linked in the post yesterday:
http://journalof911studies.com/volume/2007/LeggeVerticalCollapseWTC7_6.pdf
In particular note the small amount of fire on the north side of the building and complete absence of any hot fire above floor 12. Make sure you also read the notes at the end where there is a discussion of the way in which collapse can be seen occurring high up where there was no hot fire. Do not forget that there is a line of stout columns all around the walls of this building – if a wall is not hot these columns are not hot.

Make a thorough study of these papers and see if you do not agree that verticality of collapse indicates the use of explosives.

Paul.L

A further point. You say that the period of free fall described in the first video I linked was short, about 2 seconds, as though this enabled the observation to be ignored.

It is simple to work out how far the roof fell in this time as you would know. Others may not know, so I will spell it out. When something is dropped on earth it falls a distance given by:

at^2/2

where a is acceleration (9.8 metres per second per second)
t is time in seconds and ^2 means "to the power of 2" or "squared".

This comes to 19.6 metres. As each storey is about 3 metres this comes to over 6 storeys. This means the top of the building dropped for over 6 storeys before it encountered any resistance.

"any resistance"!

I admit it is a scary thought and most people have trouble with it. Your reaction is perfectly normal

Dagget and Amoeba,

Related was a poor choice of words. What I meant to say was that "if" amoeba were actually Dagget, Caofonix james et al" then I would be rather annoyed and would consider more action.

Dagget,

Can surely understand why i would be concerned, after spending all this time, if you were to attempt to change the direction of the debate by changing your name, effectively lying. I really don't care if amoeba is related to you at all. What I really was implying was that you were the same person.

It seems unlikely that Amoeba is Dagget etc so the issue is moot. Although CJ will no doubt let us know.

Amoeba,

You seem to have ignored the fact that the building progressively collapsed, even though it is at odds with your original position. I’ll give you the benefit of the doubt and go along with the idea that you just worded things poorly, that you knew all along the building collapsed progressively.

Firstly, I accede only to the possibility that parts of the building were in freefall for a short period of time. The analysis on the “you tube” video is very basic, and requires that we take the timeline provided on trust. Given the amount of lying the various "truther" websites undertake, I would have a VERY hard time taking their word for it. NISTs analysis suggests that the building collapsed at a rate 40% slower than freefall. But for the sake of argument we’ll take their (the trufers) word for it

>> 1. The link below provides proof that the roof of WTC7 fell for part of the time at free fall acceleration, as near as could be measured.

Not proof. As mentioned above I would need to see an independent analysis of the timeframes and floor levels. I won’t just be taking their word for it, however we can continue on as if I could.

>> 2. Free fall acceleration indicates that no upward force was experienced by the falling section of the building.

TBC

CONT

Yes. As worded, that’s fine. It’s another thing to extrapolate that to the whole building and claim that because one part (in this case the exterior right top corner) may have been in freefall, none of the columns of the builing were intact or providing resistance. See 3 below.

>> 3. No upward force implies that all support columns were, during the period of free fall, TOTALLY severed.

No if by ‘all’ you mean ‘ALL’of WTC7’s columns. This makes the assumption that the whole of the exterior fell at the same speed. But the evidence produced by the video uses only the top right corner of the building as a reference. Therefore we can not safely make any assumptions about the rest of the building.

>> 4. Similarly the fact that the building started falling with almost perfect verticality implies that, once the moment of collapse arrived, ALL remaining columns must have failed simultaneously.

The exterior of the building fell ALMOST vertically. Therefore it is safe to say that the remaining columns must have failed ALMOST simultaneously. If you look at NISTs model of the collapse you will see that the interior collapse did indeed remove large sections of the exterior columns. Once the exterior columns buckled there was very little in the way of resistance until the top half of the building met the lower parts which were still intact.
http://www.nist.gov/public_affairs/releases/wtc_videos/wtc_videos.html
in particular see the collapse initiation

>> 5. Fire, even if severe, cannot be expected to produce loss of strength in every remaining steel column which is both total and simultaneous.

True and irrelevant. Fire need only cause the failure of a single member to lead to progressive collapse. This is especially important if previous member failures had transferred load to this single member.

Finally, see this article accepted for peer review in the Journal of Engineering Mechanics.
http://ascelibrary.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JENMDT000134000002000125000001&idtype=cvips&prog=normal

Why do you think that "trufers" can't get papers published in reputable scientific journals and instead resort to the rather limp "Journal" of 911 studies?

Paul.L

You say: “You seem to have ignored the fact that the building progressively collapsed,…”

I don’t know how you define “progressive collapse”. If you mean that part fell, then another part started to fall, then of course there was a progressive collapse. Obviously the eastern penthouse dropped first, then the western penthouse started to collapse from the eastern end. If you get a better video than the one you linked to you will see a clear white flash as part of the western penthouse falls away toward the east. What can make a white flash?

The thing to understand however is that the question of progressive collapse is irrelevant. For 2 whole seconds there was nothing that could be described as “progressive”. The top fell through 6 storeys during these 2 seconds and it encountered no detectable resistance. That was 6 storeys – a long way to fall without hitting something or having to push something or having something push back. How could there be nothing there to hit. How come there was no buckling steel pushing back?

You say: “NISTs analysis suggests that the building collapsed at a rate 40% slower than freefall. But for the sake of argument we’ll take their (the trufers) word for it.”

You raise a good point here. Given that part of the collapse was at free fall, NIST must have averaged in some other period of time when the building was falling much slower, or perhaps was not falling at all, pausing between two stages of collapse. I think you would have to agree, as a scientifically educated person, that to average slower, or non-existent, collapse into the time frame of concern is at best poor analysis and at worst a deliberate deception. I guess we will never know which, but it doesn’t matter. What matters is that NIST’s falsification, in that it has obscured the existence of free fall, has been exposed and we have the correct rate of fall for 2 seconds.
TBC

You then state that this calculation is not proof by itself and you want an independent analysis. I provided one, based on a different video. It is not quite as accurate and does not detect an exact free fall, so it probably averages in the very short period of slower movement at the beginning; nevertheless it shows a fall rate very close to free fall, so close that it is unrealistic to assert that there was any significant resistance from the columns during the fall. For your convenience I repeat the link to this paper:
http://journalof911studies.com/volume/200611/911-Acceleration-Study-Proves-Explosive-Demolition.pdf

>> 2. Free fall acceleration indicates that no upward force was experienced by the falling section of the building.

You go on: “Yes. As worded, that’s fine. It’s another thing to extrapolate that to the whole building and claim that because one part (in this case the exterior right top corner) may have been in freefall, none of the columns of the building were intact or providing resistance.”

Let’s consider that for a moment. If there were some columns resisting somewhere we would see the roof in that region lagging behind the corner we are following, but we do not. I think you will have to limit your comment to “As worded, that’s fine”. But what if it were true that some columns were resisting and the roof away from the corner was lagging? It would still not refute the case we are making because, even if only part of the building is encountering no resistance for 6 storeys, that part still has to be accounted for and only explosives can do that