Im conversing with some CT's about the collapse times of the towers and their conjectures about conservation of momentum. They claim that the observed times are too short and the explanations from folks like Bazant, Greening, and our own Newton's Bit dont jibe with the laws of conservation of momentum.
This is what we in the debunking community refer to as "a lie". Greening's calculations are
based on the law of conservation of momentum.
What I'm looking for is a simple explanation for why the towers could have come down inside of 12-15 seconds or so and still taken into account conservation of momentum. The way I understand Newton's Bit is that the collapse once started would be almost effortless due to buckling modes and the amount of and type of destruction and deformation of materials once you had initiation. It seems intuitive to me but some CT's using math (dangerous I know!) claim it had to be "helped" in order to come down so quickly.
Their argument is the buildings mass poses some resistance so the collapse could never progress as quickly as it did.
Any help with this is appreciated.
Thanks.
OK, there are two issues that are getting confused here, and I'm sure the CT's wouldn't want to do anything to clear up that confusion.
First of all, there's conservation of momentum. The idea here is that every floor weighs something. Each time the top part of the tower hits another floor, that floor isn't moving, so the top part has to speed up that floor to match the speed it's falling at. That means that the top part loses a bit of momentum, and that makes it slow down a bit. It then accelerates down until it hits the next floor. By this time it's going faster than when it hit the last floor. Again it slows down a bit, but even after it's slowed down it's still falling faster than after it slowed down at the previous floor.
The amount the top block slows down depends on how heavy it is, and how heavy the floor below is. For the North Tower, the top block was about thirteen floors, so it only slowed down by one-thirteenth when it hit the first floor down. The weight of that floor was then added to the overall mass, and so the next floor slowed it even less, by one-fourteenth. And so on down.
That's a simple description without any math. To get the actual numbers, you have to do the actual math. Greening's done that, and got something in the region of 12 seconds for the total collapse. I've done the same myself, and so have some truthers. Everyone who actually works out the arithmetic finds out that the conservation of momentum approach gives something a bit shorter than the actual collapse time. Hence, we get back to my first point; when truthers say that the collapse times don't agree with the conservation of momentum, they're lying.
Now the second issue: the support columns. Truthers like to say that the columns would have slowed down the collapse much more because they're made of steel so they're very strong. However, when a steel column breaks, it does so by buckling; the column bends sideways, then breaks. Once it's broken, it isn't doing anything to slow down the collapse. So although it slows down the collapse a lot before it breaks, on average - since most of the collapse takes place after the column breaks, and before the top block hits the next one - most of the time, it isn't there to slow down the collapse, because it's already broken. Greening, Newtons Bit and Gregory Urich have all worked out the collapse times including the effect of column resistance, but - and here's the bit the truthers are lying about - they all accounted for conservation of momentum
as well, and
with both effects they end up with collapse times of around 13-16 seconds.
I hope that's kept clear enough of the technical language, but I'll say it one more time: the simple, non-technical explanation is that the truthers who say Greening and Newtons Bit's calculations ignore the conservation of momentum, are lying.
Dave
