Consistent with physical principles

MicahJava says that it's somehow a terrible thing that the sentence "consistent with physical principals" [sic] which was present in the draft version of the NIST report on WTC7, was removed from the final version.

I'm going to analyse that here.

The wording appears in the draft reports in a 4-paragraph summary of NIST's analysis of collapse time (NCSTAR 1A draft, section 3.6, pp. 40-41, PDF 78-79), and then again in a 6-paragraph explanation (NCSTAR 1-9 draft, volume 2 section 12.5.3, pp. 595-596, PDF 297-298). It's a very brief analysis and the whole paragraph where it appears reads as follows in both volumes:

Thus, the actual time for the upper 18 stories to collapse, based on video evidence, was approximately 40 percent longer than the computed free fall time and was consistent with physical principles.

NCSTAR 1-9 contains what appears to be a mistake, because this paragraph follows the previous one:

The actual collapse time of the upper 18 floors of the north face of WTC 7 (the floors clearly visible in the video evidence) was 40 percent greater than the computed free fall time. This was consistent with physical principles.

which basically says the same thing twice (it's a draft after all).

What happened in the final version? The relevant volumes are again 1A and 1-9 vol.2. The wording in 1A goes like this:

Thus, the average time for the upper 18 stories to collapse, based on video evidence, was approximately 40 percent longer than the computed free fall time.

A more detailed examination of the same video led to a better understanding of the vertical motion of the building in the first several seconds of descent. [...]

It then goes into details as to how there were three stages in the collapse, and concludes with this paragraph:

As noted above, the collapse time was approximately 40 percent longer than that of free fall for the first 18 stories of descent. The detailed analysis shows that this increase in time is due primarily to Stage 1. The three stages of collapse progression described above are consistent with the results of the global collapse analyses discussed in Chapter 12 of NIST NCSTAR 1-9.

The wording in 1-9 is similar. Chapter 12 of NIST NCSTAR 1-9 happens to be the global LS-DYNA model. This program performs a simulation based on physical principles, therefore the draft and the final report are basically saying the same thing.

But hey, it gives MicahJava chills. Go figure.

via International Skeptics Forum http://ift.tt/2t4OpY7