In its July 2008 Draft Report for Public Comment, the National Institute of Standards and Technology (NIST) initially claimed that Building 7 collapsed 40% slower than free fall acceleration.[i]
Why would NIST want to say Building 7 did not experience free fall? NIST’s lead technical investigator, Shyam Sunder, stated in the WTC 7 technical briefing that free fall could only happen when an object “has no structural components below it.”[ii] The only way for a building to have no structural components below it is to remove the lower structural components with an external force such as explosives. If the upper part of a building is crushing its lower structural components, in other words, doing the work of removing them, not all of its energy will be converted into motion and its descent will not be free fall.
A high school physics teacher named David Chandler objected to NIST’s initial claim, pointing out that, based on video footage of Building 7’s destruction, NIST’s claim contradicted “a publicly visible, easily measurable quantity.”[iii] Mr. Chandler wrote a comment to NIST, saying, “Acknowledgement of and accounting for an extended period of free fall in the collapse of WTC 7 must be a priority if NIST is to be taken seriously.”[iv]
Responding to the criticism, NIST in its final report issued in November 2008 did finally acknowledge that Building 7 descended at free fall. According to NIST, “This free fall drop continued for approximately 8 stories, or 32.0 meters (105 ft), the distance traveled between times t = 1.75 s and t = 4.0 s [a period of 2.25 seconds].”[v] However, NIST did not attempt to explain how Building 7’s free fall descent could have occurred.
However, Mr. Chandler does explain how in Part 3 of his video, NIST Finally Admits Freefall, saying:[vi]
“In the case of a falling building, the only way it can go into free fall is if an external force removes the supporting structure. None of the gravitational potential energy of the building is available for this purpose, or it would slow the fall of the building. The fact of free fall by itself is strong evidence of explosive demolition, but the evidence of explosive demolition is even stronger than that.”
Mr. Chandler goes on to describe two particular attributes of Building 7’s free fall descent that make the evidence for explosive demolition even more overwhelming:
“What is particularly striking is the suddenness of onset of free fall. Acceleration doesn’t build up gradually. The graph [measuring the building’s descent] simply turns a corner. The building went from full support to zero support instantly.”
“The onset of freefall was not only sudden, it extended across the whole width of the building… The fact the roof stayed level shows the building was in free fall across the entire width.”
Mr. Chandler summarizes the meaning of these observations, saying:
“The collapse we see cannot be due to a column failure, or a few column failures, or a sequence of column failures. All 24 interior columns and 58 perimeter columns had to have been removed over the span of 8 floors low in the building simultaneously to within a small fraction of a second, and in such a way that the top half of the building remains intact and uncrumpled.”
Only explosives can instantaneously remove 8 stories allowing the upper structure to accelerate downwards in free fall. The absolute free fall of Building 7 over a period of 2.25 seconds is by itself overwhelming evidence that explosives were used to bring down the building.
[i] National Institute of Standards and Technology (NIST), “Final Report on the Collapse of World Trade Center Building 7 – Draft for Public Comment,” Washington, DC. August 2008. Chapter 3 p.41. http://wtc.nist.gov/media/NIST_NCSTAR_1A_for_public_comment.pdf
[ii] NIST WTC 7 Technical Briefing, August 26, 2008. http://911speakout.org/NIST_Tech_Briefing_Transcript.pdf Transcript p.16
[iv] Quoted by David Ray Griffin, “The Mysterious Collapse of WTC 7: Why NIST’s Final 9/11 Report is Unscientific and False,” GlobalResearch.ca, September 14, 2009. http://globalresearch.ca/index.php?context=va&aid=15201
[v] NIST NCSTAR 1A, “Final Report on the Collapse of World Trade Center Building 7,” Washington, DC. November 2008. p.45 http://wtc.nist.gov/NCSTAR1/