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Originally posted by dubiousone
The time of 9.2 seconds is based on free-fall in a vacuum. Remember, Manhattan is at sea level on earth, not in outer space, though some might disagree on the latter point. Taking into account the air resistance at sea level, it appears that the towers indeed fell at near free-fall speed. There's a straightforward discussion of the issue at 911blimp.net...
Originally posted by Slap Nuts
I believe her middle ground... while totally over simplified "start stop every ten floors" makes a basic case for the length of time the pancaking would take to occur. Some of the momentum is conserved BUT much KE is lost in order to "break" the resistance of the undamaged structure.
1. Kenetic energy is required to start the next floor moving because it is intact.
2. Not all of the momentum will be conserved because of the lost KE in #1.
3. This should have slowed the descent considerably from what we observed.
4. The only energy available at the onset was G.
Originally posted by wecomeinpeace
What you're saying here is that the figure arrived at by incorrect method A should probably be roughly the same as what you think the figure arrived at by correct method B would be, so method A is therefore valid.
Originally posted by wecomeinpeace
I agree with all of the above (except the energy available was the PE)
Originally posted by Slap Nuts
That is not what I meant. In A, she basiclly indicates that ALL of the momentum would be stopped at every floor... In B it does not stop at all in 9 floors... then stops at 10... this kind of averages out the conservation of momentum across 10 floors. At least in my head.
Originally posted by Skadi_the_Evil_Elf
No, my opinion has not changed. When I used the term freefall, I was using the 14 second figure. Val came up with 16 seconds for another tower. So technically, it wasn't "free fall" in the most literal sense.
Originally posted by Skadi_the_Evil_Elf
But it was still entirely too fast given the building and circumstances. Please read my later posts for details of my view on this.
Originally posted by Skadi_the_Evil_Elf
Absolutely not. Again, they fell at pretty much near a freefall speed. They fell entirely too fast. It looked like freefall speed to me, even though freefall is much lower speed. Read my later posts for my clarification of this.
Originally posted by Skadi_the_Evil_Elf
Like I said, I am yet to hear a credible answer as to why building 7 collapsed. The offical story is, well.........unbelievable. Many more buildings should have collapsed on their own if this was the case.
Originally posted by Muaddib
Skadi...there is only one speed for freefall, and that is due to gravity alone..
Sorry, but watching some buildings being demolished in your spare time does not make you an expert. you can have your own opinion if you want but it is still wrong.
1/3 the speed of freefall, or gravity, is nowhere near the buildings falling at freefall. What I see here is like with so many other people, when you are presented with evidence that disproves such claims, you still deny the facts.
Nope, not all of them were as high as WTC7, which did play a part in the collapse, not all of them were hit with debri from the Twin towers which took part of wtc7, and WTC5 which was in between one of the twin towers and WTC7 was also demolished, the debri from that building also hit WTC7. If i remember correctly there were some other buildings that also collapsed but just because some collapsed doesn't mean "they all had to collapse".
Originally posted by Muaddib
BTW, VAlhall, if there was only 250 C temperature at the WTC from the fires, how is that possible when temperatures in a residential fire often reach 500 C to 650 C?
So how come the fires at the WTC were less than those in a residential fire?
[edit on 30-7-2006 by Muaddib]
Originally posted by Griff
Steel is a heat sink and will wick the heat away from the source.
Originally posted by HowardRoark
Which particular pieces of steel are you referring to?
The floor trusses?
They were rather thin.
fire-research.group.shef.ac.uk...
taking out the core columns by some means to initiate floor trusses to sag/rendering the designed 50% gravity load resistance gone/rendering the lateral support of the exterior columns null.
Originally posted by Vushta
But wouldn't that scenerio pull in on the outer columns in a very general way if the trusses were still connected to the core causing obvious distorting of the outer face of the building?
Originally posted by Valhall
Originally posted by Vushta
But wouldn't that scenerio pull in on the outer columns in a very general way if the trusses were still connected to the core causing obvious distorting of the outer face of the building?
I believe they did just that, didn't they?
Originally posted by Vushta
On a couple of floors over a period of time as far as I know. At least thats what the pictures show.
I was refering to the sudden 'removal' of the core via a series of rapid explosions. If it suddenly dropped it would seem that there should have been visual evidence of a sort of accordian effect all around the towers. But the way it looks to me the forces were basically isolated around the leading head of the collapse.
Originally posted by Valhall
I understand what you're saying now, and kind of agree, and kind of don't.
The floor truss connections were failed at the outer perimeter in a downward motion (and that's for almost all the specimens they looked at), while the truss connections on the core columns were not (and that's for almost all the specimens they looked at). To me this is indicative of the core columns failing and bringing the floor trusses down with them. The part I don't agree with is equating the core column failures to "taking out the core columns"...they're still there, they're just falling now and dragging down everything.
What I want explained to me is how the opposite wall of WTC 2 - which was in severe tension at the time the top was listing approximately 20 degrees from vertical, suddenly failed in compression to the point it righted the top of the tower?
That's the one I keep hanging in this thread for - an explanation I can buy on that one.
The downloadable full report contains eight articles that deal with the September 11, 2001 World Trade Center (WTC) disaster and its consequences, written by researchers at the Massachusetts Institute of Technology. For the most part, these articles were prepared between September 2001 and February 2002, and were revised in part in the spring of 2002.[/e]
web.mit.edu...
Originally posted by Valhall
What I want explained to me is how the opposite wall of WTC 2 - which was in severe tension at the time the top was listing approximately 20 degrees from vertical, suddenly failed in compression to the point it righted the top of the tower?
That's the one I keep hanging in this thread for - an explanation I can buy on that one.
Originally posted by Duhh
M.I.T. research essays here guy's ! Whew is that alot of reading. Y'all sure are good at math. Lot's O' this stuff way over my head, here, but I'm learning. From what I see here they buy the Gov. line. They are independent , in the sense they aren't USG ! If ya ain't seen this yet,check it out ! Happy Hunting!
The downloadable full report contains eight articles that deal with the September 11, 2001 World Trade Center (WTC) disaster and its consequences, written by researchers at the Massachusetts Institute of Technology. For the most part, these articles were prepared between September 2001 and February 2002, and were revised in part in the spring of 2002.[/e]
web.mit.edu...
Originally posted by Duhh
What is with all the anger here? This is not surgery ! You are not the only people here. The info was posted for those who haven't . Geeze have a time-out , or something.