Dr. G wrote:T. Szamboti:
I find it interesting that you apparently want to compare the collapse of WTC 1 with the collapse of the ABC Tower in France, and consider one to be "natural" and the other, presumably, to be "unnatural". The question is: which is which?
But be that as it may, when you say there was negative acceleration in the ABC Tower collapse, I am not so sure. And I have measured the collapse rate over the first 2.5 seconds and all I can say is that a jolt is possibly present, but only as a reduction in downward acceleration after 7 meters of drop. However, negative acceleration is never present as far as I can tell.
What I find most interesting right now is how the ABC Tower was "pulled" by those clever French engineers, and the possibility that there may have been an acceleration greater than g over the first 7 meters. Now this is reminiscent of WTC 7
But this shows that the ABC demolition was far from being "natural", thus I would not expect WTC 1 to replicate the ABC collapse - on the contrary, I would expect it to be quite different!
I don't know how you are measuring the fall of the upper block in the abc tower, but we are using the same recognized method which forced the NIST to acknowledge the freefall of the upper block of WTC 7 for 2.25 seconds.
The slope on the velocity curve actually reverses direction in the plot of the data taken of the fall of the upper block from the abc tower demolition. This is a negative acceleration and provides evidence of a mechanism for the load amplification necessary to allow the statically undersize load above to overload the columns below. This is not present in the measurements of the fall of the upper block of WTC 1, and since there is no other natural mechanism to allow the upper block to overload the columns of the lower block, it's destruction had to have been assisted by means other than the weight of the upper block.
We aren't getting greater than g acceleration in our measurements of the fall of the abc tower upper block. If you are, I think it is likely to be measurement error. Even if there was greater than g acceleration, possibly due to some form of whip action, it is insignificant to the issue of whether or not an impulse occurred to provide a natural mechanism for the destruction and collapse of the lower block to occur.