NISTのWTC7報告書正式版(要約)での自由落下に関する記述
NIST NCSTAR 1A: Final Report on the Collapse of World Trade Center Building 7
ttp://wtc.nist.gov/NCSTAR1/PDF/NCSTAR%201A.pdf (
ttp://wtc.nist.gov/NCSTAR1/NCSTAR1Aindex.htm )
> In Stage 2, the north face descended at gravitational acceleration, as the buckled columns
> provided negligible support to the upper portion of the north face. This free fall drop continued
> for approximately 8 stories or 32.0 m (105 ft), the distance traveled between times t = 1.75 s and
> t = 4.0 s.
(p.45)
Figure 3?. Downward velocity of north face roofline as WTC 7 began to collapse.
(p.46)