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EXPLOSIVES POWERED THE 9-11 WORLD TRADE CENTER
Wed Dec 10 15:39:26 2003
64.140.158.177

EXPLOSIVES POWERED THE 9-11 WORLD TRADE CENTER DUST CLOUDS.
by XXXX • Tuesday December 09, 2003 at 02:46 PM
http://vancouver.indymedia.org/news/2003/12/91767.php

This paper uses photographic evidence -- primarily a reference photograph taken from FEMA report -- to estimate the volume of the dust cloud that grew from the collapse of the North Tower at about 30 seconds after the commencement of the collapse. The paper estimates the quantity of explosive necessary to produce the observed expansion in the volume of the dust cloud.

The North Tower's Dust Cloud
Analysis of Energy Requirements for the Expansion of the
Dust Cloud following the Collapse of 1 World Trade Center
by Jim Hoffman, October 16th, 2003
[Version 3.0]
Abstract

This paper uses photographic evidence -- primarily a reference photograph taken from FEMA's report -- to estimate the volume of the dust cloud that grew from the collapse of the North Tower at about 30 seconds after the commencement of the collapse. The paper then estimates the thermal energy required to produce the observed expansion in the volume of the dust cloud, based on the assumption that most of the gasses and suspended solids in the cloud originated from within the building.

The most recent version of the paper identifies two major mechanisms for the expansion -- thermodynamic expansion of gasses due to increases in temperature, and expansion due to the vaporization of water. Both represent vast energy sinks. Whatever the relative contributions of these mechanisms to the expansion, the required energy inputs far exceeds the energy available in the form of the gravitational potential energy due to the tower's elevated mass.

Previous versions of the paper did not consider expansion due to water vaporization, and considered only thermodynamic expansion of gasses present in the building at the time of collapse. That required average dust cloud temperatures of around 1000 K, a feature several people found implausible. The addition of the heat of water vaporization to the analysis changes the picture dramatically. The heat energy requirements are similar, but the temperatures need not have been anywhere near 1000 K, since the phase change of water to steam occurs at 100 C.

The paper shows a large disparity between the energy required to produce the observed expansion of the dust cloud and that available from the conversion of all the tower's gravitational potential energy to heat. It does not consider the possible energy source of the unlikely rapid combustion of the tower's contents during its collapse, but even the energy available from consuming all of the oxygen in the tower to burn hydrocarbons is far short of the estimated size of the energy sink of dust cloud expansion.

On September 11th, both of the Twin Towers disintegrated into vast clouds of concrete and other materials, which blanketed Lower Manhattan. This paper shows that the energy required to produce the expansion of the dust cloud observed immediately following the collapse of 1 World Trade Center (the North Tower) was much greater than the gravitational energy available from its elevated mass. It uses only basic physics.
Introduction

Vast amounts of energy were released during the collapse of each of the Twin Towers in Lower Manhattan on September 11th, 2001. The accepted source of this energy was the gravitational potential energy of the towers, which was far greater than the energy released by the fires that preceded the collapses. The magnitude of that source cannot be determined with much precision thanks to the secrecy surrounding details of the towers' construction. However, FEMA's Building Performance Assessment Report gives an estimate [Ref. (1)]: "Construction of WTC 1 resulted in the storage of more than 4 x 1011 joules of potential energy over the 1,368-foot height of the structure. "That is equal to about 111,000 KWH (kilowatt hours) per tower.

Of the many identifiable energy sinks in the collapses, one of the only ones that has been subjected to quantitative analysis is the thorough pulverization of the concrete in the towers. It is well documented that nearly all of the non-metallic constituents of the towers were pulverized into fine powder. The largest of these constituents by weight was the concrete that constituted the floor slabs of the towers. Jerry Russell estimated that the amount of energy required to crush concrete to 60 micron powder is about 1.5 KWH/ton. [Ref. (2)]. That paper incorrectly assumes there were 600,000 tons of concrete in each tower, but Russell later provided a more accurate estimate of 90,000 tons of concrete per tower, based on FEMA's description of the towers' construction. That estimate implies the energy sink of concrete pulverization was on the order of 135,000 KWH per tower, which is already larger than the energy source of gravitational energy. However, the size of this sink is critically dependent on the fineness of the concrete powder, and on mechanical characteristics of the lightweight concrete thought to have been used in the towers. Available statistics about particle sizes of the dust, such as the study by Paul J. Lioy, et al [Ref. (3)], characterize particle sizes of aggregate dust samples, not of its constituents, such as concrete, fiberglass, hydrocarbon soot, etc. Based on diverse evidence, 60 microns would appear to be a high estimate for average concrete particle size, suggesting 135,000 KWH is a conservative estimate for the magnitude of the sink.

A second energy sink, that has apparently been overlooked, was many times the magnitude of the gravitational energy: the energy needed to expand the dust clouds to several times the volume of each tower within 30 seconds of the onset of their collapses. Note that the contents of the dust clouds had to come from building constituents -- gases and materials inside of or intrinsic to the building -- modulo any mixing with outside air. Given that the Twin Towers' dust clouds behaved like pyroclastic flows, with distinct boundaries and rapidly expanding frontiers (averaging perhaps 35 feet/second on the ground for the first 30 seconds), it is doubtful that mixing with ambient air accounted for a significant fraction of their volume. Therefore the dust clouds' expansion must have been primarily due to an expansion of building constituents. Possible sources of expansion include:

* thermodynamic expansion of gases
* vaporization of liquids and solids
* chemical reactions resulting in a net increase in gaseous phase molecules That is explosives.

The evidence does not support the idea that chemical reactions in the dust cloud liberated vast quantities of gases.

Actually, the evidence does support the use of explosives to collapse the towers [Ref. (4)].
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• 9-11 - A total blackout on information — Daniel Hopsicker, Wed Dec 10 16:39