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Alex_V
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Joined: 24 Sep 2007
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Location: London, England
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 Posted: Thu Nov 08, 2007 6:19 pm Post subject: Basic Physics and WTC Collapse |
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This post is generally a reply to kbo234 from the articles forum (http://www.nineeleven.co.uk/board/viewtopic.php?t=11852) - I thought it would be worth answering it in critics corner to introduce the topic to the debate. It refers to the WTC collapses, and is a description of why kbo234 and others in the truth movement believe that basic physics refutes the NIST official collapse theory.
In tackling this subject, I readily admit that I am no physicist. I am happy to be proved wrong, and I put my take on it forward to encourage debate.
| Quote: | Their own estimated time of collapse of the South Tower, assuming they believe this to be accurate, is proof of controlled demolition.
Their figure of 9 seconds is actually less than the calculated time of free-fall collapse (9.22 seconds). |
Utterly false. NIST's 9 seconds for WTC2 is actually their calculation of when the first exterior panels hit the ground, based on seismic readings and the available footage. It is NOT their calculated time of collapse.
The simplest way to refute the idea that the towers collapsed at free-fall speed is to examine the pictures of debris from the collapse that is falling below the line at which the tower is collapsing.
| Quote: | | Starting with this data as fact, any reasonably able year 11 schoolchild can tell you that there exist two laws of physics, the laws of conservation of momentum and conservation of energy, both of which exclude the possibility of natural free-fall collapse of such a vertically-stacked rigid structure. |
That data is not the fact you say it is, as I have already stated. So you are arguing this case from a false starting point, as is the truth movement in general IMO.
| Quote: | | 1) Conservation of momentum basically recognises and quantifies the universal fact of the physical world that every 2-year old child instinctively understands (in much the same way they understand that if you drop something it falls to the ground) ........that moving objects are slowed down when they collide with stationary objects. |
Nonsense. Conservation of momentum states that momentum is conserved in collisions.
| Quote: | | Hence, the impact of floor-on-floor, had such impacts taken place, would certainly have increased the time of collapse. Many estimates of reasonable collapse times have been made, ranging from about 20 to 60 seconds. |
What about Frank Greening's estimate? Is that reasonable? Greening is an outspoken critic of NIST, but he estimates a collapse time of 11.5 seconds. He provides his estimate in his 9/11 paper...
http://www.911myths.com/WTCREPORT.pdf
Well worth a read, particularly as it blows most of what you have said here out of the water. There may well be estimates of longer collapse times from within the truth movement, and I accept that you have to take each case on its merits. But I hope that at least I am persuading you (or somebody) that there is a debate here. Not just the 'truth' versus 'lies'.
| Quote: | | However the simple point to understand is that in this case the supposed impacts of floor-on-floor cause no slowing down at all. |
Your assertion - no OT supports this idea. You are attacking a 'strawman' basically.
| Quote: | | Thus free-fall collapse is physically impossible without the consecutive destruction of supports down the length of the building. |
See above.
| Quote: | | 2) Conservation of energy stipulates that for any free-falling body ALL potential gravitational energy is converted into kinetic energy of motion. |
Agreed. But the important point to remember here is the kinetic energy - and what happens to it during the collapse!
| Quote: | | Therefore....where did the energy come from to pulverise most of the building while it was falling at free-fall speed through itself? (we all saw this happening with our own eyes didn't we?) |
Opinion as fact. Was most of the building pulverised while it was falling? You make it sound as if the official theory suggests that no part of the building came into contact with any other as the building collapsed. I accept that debris and a dust cloud were created as the building collapsed, but you will have to persuade me that this was 'most' of the building.
| Quote: | | There was NO energy available to do this...... |
Well where did the energy go then? Your assumption seems to be that the 'kinetic energy of motion' is sort of... used up... as the building falls, but as already noted your very own conservation of energy theory already dictates that this isn't the case.
| Quote: | | .........without the use of explosives. |
See what I'm getting at now? I'm not saying that explosives couldn't have done it btw, just that the evidence that they HAD to be used is not compelling at all based on what you have just said.
| Quote: | | NIST's saying that they could 'find no evidence' of controlled demolition is disingenuous, dissembling and dishonest. |
I disagree, at least based on the rubbish suggested here to disagree with their assertion. |
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James C
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Joined: 26 Jan 2006
Posts: 1046
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| Posted: Thu Nov 08, 2007 7:42 pm Post subject: |
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| Alex_V wrote: | What about Frank Greening's estimate? Is that reasonable? Greening is an outspoken critic of NIST, but he estimates a collapse time of 11.5 seconds. He provides his estimate in his 9/11 paper...
http://www.911myths.com/WTCREPORT.pdf
Well worth a read, particularly as it blows most of what you have said here out of the water. There may well be estimates of longer collapse times from within the truth movement, and I accept that you have to take each case on its merits. But I hope that at least I am persuading you (or somebody) that there is a debate here. Not just the 'truth' versus 'lies'. |
What Greening fails to grasp or even question properly is how each floor can work as a homogenous element; stiff enough to fall as one piece away from the core and facade to which it is attached. Even a brief anaylsis of the construction will reveal how the floor is made up of elements - trusses, metal decking, lightweight concrete screed. How on earth could these elements have held together enough to have fallen intact across the entire floor plan to impact the floor below? It assumes that each connection (of which there were many) supporting the trusses magically disappeared at the same time in order that the floors could fall as one unit. Simple observation shows that the buildings fell apart from the top down which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below.
It is all very well to apply the formulae that he does but if he cannot grasp the construction and behaviour of falling structures then it remains purely hypothetical. |
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marky 54
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| Posted: Fri Nov 09, 2007 4:06 am Post subject: |
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| Quote: | | What Greening fails to grasp or even question properly is how each floor can work as a homogenous element; stiff enough to fall as one piece away from the core and facade to which it is attached. Even a brief anaylsis of the construction will reveal how the floor is made up of elements - trusses, metal decking, lightweight concrete screed. How on earth could these elements have held together enough to have fallen intact across the entire floor plan to impact the floor below? |
i think you'll find it is'nt just Greening failing to grasp that. |
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pepik
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| Posted: Fri Nov 09, 2007 7:09 am Post subject: |
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| Quote: | | Simple observation shows that the buildings fell apart from the top down which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below. |
This is complete and utter pulled-out-of-a-hat nonsense.
Why does 911 troof make people think physics and engineering principles can just be made up as you go along?
_________________
"could it be that ww2 and the extermination of jewish people was planned as a way of creating a race of people who it would be difficult to blame for anything, a cover race for the illuminati?" - a quote NOT from the 'controversial theories' section. |
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marky 54
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| Posted: Fri Nov 09, 2007 7:17 am Post subject: |
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| pepik wrote: | | Quote: | | Simple observation shows that the buildings fell apart from the top down which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below. |
This is complete and utter pulled-out-of-a-hat nonsense.
Why does 911 troof make people think physics and engineering principles can just be made up as you go along? |
why do leaders think giving the public true information can be made up as they go along?
why did the commssion report just make things up as it went along etc etc.
it can be applied to a lot of things, however you offer no reference as to what is made up and why, you just simply say it which anyone can do about anything.
| Quote: | | Simple observation shows that the buildings fell apart from the top down |
is that false?
| Quote: | | there just wasn't the momentum there from above to have destroyed that which was below. |
or that?
or both? |
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Bushwacker
Relentless Limpet Shill
Joined: 07 Sep 2006
Posts: 1628
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| Posted: Fri Nov 09, 2007 9:48 am Post subject: |
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| James C wrote: | | Alex_V wrote: | What about Frank Greening's estimate? Is that reasonable? Greening is an outspoken critic of NIST, but he estimates a collapse time of 11.5 seconds. He provides his estimate in his 9/11 paper...
http://www.911myths.com/WTCREPORT.pdf
Well worth a read, particularly as it blows most of what you have said here out of the water. There may well be estimates of longer collapse times from within the truth movement, and I accept that you have to take each case on its merits. But I hope that at least I am persuading you (or somebody) that there is a debate here. Not just the 'truth' versus 'lies'. |
What Greening fails to grasp or even question properly is how each floor can work as a homogenous element; stiff enough to fall as one piece away from the core and facade to which it is attached. Even a brief anaylsis of the construction will reveal how the floor is made up of elements - trusses, metal decking, lightweight concrete screed. How on earth could these elements have held together enough to have fallen intact across the entire floor plan to impact the floor below? It assumes that each connection (of which there were many) supporting the trusses magically disappeared at the same time in order that the floors could fall as one unit. Simple observation shows that the buildings fell apart from the top down which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below.
It is all very well to apply the formulae that he does but if he cannot grasp the construction and behaviour of falling structures then it remains purely hypothetical. |
I don't think his calculations depend at all on the floors staying intact, their mass obviously stays the same whether intact or broken apart. Your idea that they turned to dust as they fell is not supported by any evidence that I have seen. |
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Mark Gobell
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Joined: 24 Jul 2006
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| Posted: Fri Nov 09, 2007 10:42 am Post subject: |
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| Bushwacker wrote: | | Your idea that they turned to dust as they fell is not supported by any evidence that I have seen. |
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The Medium is the Massage - Marshall McLuhan. |
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Stefan
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| Posted: Fri Nov 09, 2007 11:35 am Post subject: |
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Hi all,
Something people don't seem to point out enough is that on planet earth it is actually impossible for something to fall at "free fall speed".
When people use the term "free fall speed" they refer to the result of the calculation for free fall in a vacume - that is without air resistence, or any other kind of resistence.
A standard controlled demolition: near free fall speed.
Drop your pen off the desk: that just fell at near free fall speed.
Short of creating an artifical vacume something cannot fall at free fall speed on this planet of ours.
So the argument: WTC DIDN'T FALL AT FREE FALL SPEED is actually a straw man.
Place video of WTC7's collapse next to footage of an accepted CD, for example, and they fall at the SAME SPEED - that would be - NEAR FREE FALL SPEED, or in other words the speed of something falling through air without resistence.
That is all.
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James C
Major Poster
Joined: 26 Jan 2006
Posts: 1046
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| Posted: Fri Nov 09, 2007 5:59 pm Post subject: |
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| Bushwacker wrote: | | I don't think his calculations depend at all on the floors staying intact, their mass obviously stays the same whether intact or broken apart. Your idea that they turned to dust as they fell is not supported by any evidence that I have seen. |
The mass stays the same but it changes the way the building falls. Looking carefully, and your last comment seems to suggest that you are doing this in a different way to myself and the others on this forum, the buildings collapsed symmetrically, i.e. they they didn't topple over or collapse on one side only. Therefore the symmetry of collapse could only have happened if every part of the destruction was the same on all four sides. But the plane impacts and fires were not symmetrically placed so how could the floors have fallen downward at the same speed and with the same motion, which would have required simultaneous failure of the facade and core, to initiate such symmetry?
Greening ignores this rather major detail, probably because he has little grasp of how building work. |
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Bushwacker
Relentless Limpet Shill
Joined: 07 Sep 2006
Posts: 1628
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| Posted: Sat Nov 10, 2007 12:03 am Post subject: |
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| Stefan wrote: | Hi all,
Something people don't seem to point out enough is that on planet earth it is actually impossible for something to fall at "free fall speed".
When people use the term "free fall speed" they refer to the result of the calculation for free fall in a vacume - that is without air resistence, or any other kind of resistence.
A standard controlled demolition: near free fall speed.
Drop your pen off the desk: that just fell at near free fall speed.
Short of creating an artifical vacume something cannot fall at free fall speed on this planet of ours.
So the argument: WTC DIDN'T FALL AT FREE FALL SPEED is actually a straw man.
Place video of WTC7's collapse next to footage of an accepted CD, for example, and they fall at the SAME SPEED - that would be - NEAR FREE FALL SPEED, or in other words the speed of something falling through air without resistence.
That is all. |
Quite correct Stefan, we do not live in a vacuum, so objects do not fall at free fall speed.
WTC1 and WTC2 fell slightly slower than the speed of objects falling through air, indeed debris can be observed falling faster than the collapse wave.
There is no such convenient measure for WTC7, and the collapse was more complex generally, with a delay of some 8 seconds between the first signs, and global collapse. How the speed of the final collapse compared with a falling object I could not say. |
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Bushwacker
Relentless Limpet Shill
Joined: 07 Sep 2006
Posts: 1628
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| Posted: Sat Nov 10, 2007 12:18 am Post subject: |
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| James C wrote: | | Bushwacker wrote: | | I don't think his calculations depend at all on the floors staying intact, their mass obviously stays the same whether intact or broken apart. Your idea that they turned to dust as they fell is not supported by any evidence that I have seen. |
The mass stays the same but it changes the way the building falls. Looking carefully, and your last comment seems to suggest that you are doing this in a different way to myself and the others on this forum, the buildings collapsed symmetrically, i.e. they they didn't topple over or collapse on one side only. Therefore the symmetry of collapse could only have happened if every part of the destruction was the same on all four sides. But the plane impacts and fires were not symmetrically placed so how could the floors have fallen downward at the same speed and with the same motion, which would have required simultaneous failure of the facade and core, to initiate such symmetry?
Greening ignores this rather major detail, probably because he has little grasp of how building work. |
But in fact WTC2 did not initially collapse symmetrically, the top section fell at an angle before sight of it was obscured by the dust cloud. However, symmetrical or not, this does not seem to me to affect Greening's calculations, why should it? He is concerned with the energy involved, not the mechanism of collapse.
On the matter of dust, of course huge amounts of dust were generated as the buildings fell, so I grant you a certain proportion turned to dust. However, a large proportion, including virtually all the steel, clearly did not. |
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James C
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Joined: 26 Jan 2006
Posts: 1046
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| Posted: Sat Nov 10, 2007 8:41 am Post subject: |
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| Bushwacker wrote: | | James C wrote: | | Bushwacker wrote: | | I don't think his calculations depend at all on the floors staying intact, their mass obviously stays the same whether intact or broken apart. Your idea that they turned to dust as they fell is not supported by any evidence that I have seen. |
The mass stays the same but it changes the way the building falls. Looking carefully, and your last comment seems to suggest that you are doing this in a different way to myself and the others on this forum, the buildings collapsed symmetrically, i.e. they they didn't topple over or collapse on one side only. Therefore the symmetry of collapse could only have happened if every part of the destruction was the same on all four sides. But the plane impacts and fires were not symmetrically placed so how could the floors have fallen downward at the same speed and with the same motion, which would have required simultaneous failure of the facade and core, to initiate such symmetry?
Greening ignores this rather major detail, probably because he has little grasp of how building work. |
But in fact WTC2 did not initially collapse symmetrically, the top section fell at an angle before sight of it was obscured by the dust cloud. However, symmetrical or not, this does not seem to me to affect Greening's calculations, why should it? He is concerned with the energy involved, not the mechanism of collapse.
On the matter of dust, of course huge amounts of dust were generated as the buildings fell, so I grant you a certain proportion turned to dust. However, a large proportion, including virtually all the steel, clearly did not. |
The top section of WTC2 fell into the dust cloud, it didn't create it. The top section started to rotate only as the explosions (above and below that section) occured but then it stopped rotating and dropped vertically. Why?, because clearly the structure it was attached to, below itself, had fallen away - otherwise it would have continued to rotate until dropping off. The rest of the building (as in the case of WTC1 and WTC7) remained a symmetrical collapse or are you disputing that?
So Greening puts together a set of calculations and assumptions without even reflecting on how the building could have fallen like that. If he had stopped to consider this issue he would, just like NIST, have stopped before wasting his time. His paper is pointless.
And who said the dust cloud included steel? Have I ever said that? Of course, one has to question where the large amount of dust came from which was ejected as the top of WTC2 (and WTC1) started to fall. |
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pepik
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| Posted: Sat Nov 10, 2007 6:32 pm Post subject: |
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| Quote: | | The rest of the building (as in the case of WTC1 and WTC7) remained a symmetrical collapse or are you disputing that? |
I don't see how a symmetrical collapse could damage other buildings. | Quote: | | Of course, one has to question where the large amount of dust came from which was ejected as the top of WTC2 (and WTC1) started to fall. |
Fires which had been burning across several floors around where the building collapsed would have generated large amounts of ash. When the building collapsed this would have expelled the ash and any trapped smoke.
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"could it be that ww2 and the extermination of jewish people was planned as a way of creating a race of people who it would be difficult to blame for anything, a cover race for the illuminati?" - a quote NOT from the 'controversial theories' section. |
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Bushwacker
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Joined: 07 Sep 2006
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| Posted: Sat Nov 10, 2007 9:17 pm Post subject: |
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| James C wrote: |
The top section of WTC2 fell into the dust cloud, it didn't create it. The top section started to rotate only as the explosions (above and below that section) occured but then it stopped rotating and dropped vertically. Why?, because clearly the structure it was attached to, below itself, had fallen away - otherwise it would have continued to rotate until dropping off. The rest of the building (as in the case of WTC1 and WTC7) remained a symmetrical collapse or are you disputing that?
So Greening puts together a set of calculations and assumptions without even reflecting on how the building could have fallen like that. If he had stopped to consider this issue he would, just like NIST, have stopped before wasting his time. His paper is pointless.
And who said the dust cloud included steel? Have I ever said that? Of course, one has to question where the large amount of dust came from which was ejected as the top of WTC2 (and WTC1) started to fall. |
Ah, imaginary explosions - no doubt they explain a lot for you, although it is the first time I have heard it suggested that there were explosions above the top section. But what explains your belief that the top section of WTC2, obviously weighing thousands of tons, and rotating, is going to stop rotating because the structure below it had fallen away? That makes no sense, does it?
You said ".........which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below." You either meant floor as in storey, as I took it, which meant that the steel turned to dust as well, a la Judy Woods and her beam weapon, or you meant literally just the floor, the main weight of the building in the steel structure not being included, in which case your remark about the momentum makes no sense. |
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James C
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| Posted: Sun Nov 11, 2007 12:53 am Post subject: |
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| Bushwacker wrote: | | James C wrote: |
The top section of WTC2 fell into the dust cloud, it didn't create it. The top section started to rotate only as the explosions (above and below that section) occured but then it stopped rotating and dropped vertically. Why?, because clearly the structure it was attached to, below itself, had fallen away - otherwise it would have continued to rotate until dropping off. The rest of the building (as in the case of WTC1 and WTC7) remained a symmetrical collapse or are you disputing that?
So Greening puts together a set of calculations and assumptions without even reflecting on how the building could have fallen like that. If he had stopped to consider this issue he would, just like NIST, have stopped before wasting his time. His paper is pointless.
And who said the dust cloud included steel? Have I ever said that? Of course, one has to question where the large amount of dust came from which was ejected as the top of WTC2 (and WTC1) started to fall. |
Ah, imaginary explosions - no doubt they explain a lot for you, although it is the first time I have heard it suggested that there were explosions above the top section. But what explains your belief that the top section of WTC2, obviously weighing thousands of tons, and rotating, is going to stop rotating because the structure below it had fallen away? That makes no sense, does it?
You said ".........which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below." You either meant floor as in storey, as I took it, which meant that the steel turned to dust as well, a la Judy Woods and her beam weapon, or you meant literally just the floor, the main weight of the building in the steel structure not being included, in which case your remark about the momentum makes no sense. |
You have a terrible memory. Last year, October if I recall correctly, we discussed in the critics corner the video of WTC2 collapsing. It was this video and if you watch carefully you'll see flashes and puffs of smoke on the top section starting from the nearside corner as it falls. The critics put it down to breaking glass. I say the flashes are explosions. Either way, this issue should not be new to you so why claim that it is. Please try and keep up.
As for your last comment, you appear to be making something out of nothing. Are you really that desperate? |
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Alex_V
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Joined: 24 Sep 2007
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Location: London, England
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| Posted: Sun Nov 11, 2007 6:26 pm Post subject: |
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Gripes about the source I mentioned aside (which seems to have derailed the thread a bit), I would still like to try and understand why the way in which the towers collapsed would be physically impossible. I think it's fair to say that the truth movement has been saying for years now that the collapses defied the basic laws of physics. I would like to establish how they feel this is the case.
James - if you feel the collapse of the towers is more symmetrical than you think is physically possible, you will have to persuade me/us how this is. I know what you mean by the collapse being symmetrical, but I doubt that it was truly symmetrical in precise terms.
Basically, why wouldn't the towers collapse straight down? What evidence is there to suggest otherwise? |
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pepik
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Location: The Square Mile
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| Posted: Sun Nov 11, 2007 7:20 pm Post subject: |
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| Quote: | | and if you watch carefully you'll see flashes and puffs of smoke on the top section starting from the nearside corner as it falls |
Yes and "flashes" in midair in the smoke cloud long after the building has fallen away. I guess they packed the building with so many extra bombs that they just went flying everywhere, and since they were so lightweight some just floated up with the smoke and exploded later due to problems with the timers?
Remember to make sense James. Would make your conspiracy theories more convincing.
_________________
"could it be that ww2 and the extermination of jewish people was planned as a way of creating a race of people who it would be difficult to blame for anything, a cover race for the illuminati?" - a quote NOT from the 'controversial theories' section. |
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KP50
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Location: NZ
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| Posted: Sun Nov 11, 2007 7:43 pm Post subject: |
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| Alex_V wrote: | Gripes about the source I mentioned aside (which seems to have derailed the thread a bit), I would still like to try and understand why the way in which the towers collapsed would be physically impossible. I think it's fair to say that the truth movement has been saying for years now that the collapses defied the basic laws of physics. I would like to establish how they feel this is the case.
James - if you feel the collapse of the towers is more symmetrical than you think is physically possible, you will have to persuade me/us how this is. I know what you mean by the collapse being symmetrical, but I doubt that it was truly symmetrical in precise terms.
Basically, why wouldn't the towers collapse straight down? What evidence is there to suggest otherwise? |
OK try this one - the top of WTC2 undoubtedly tilts at a fair angle as it starts to drop. Imagine the side of the building at the far side of the tilt - that is the side with the least mass bearing down on it. Given the lack of mass, how does this side still manage to crumble all the way down to the bottom? Would it not be more inclined to be pulled to the side by the rest of the building as the mass bears down on it.
Or to summarise, if a building is going to collapse from top to bottom because of the weight of the top section, surely that weight would have to be bearing down equally on all parts of the building?
And for your bonus question - wouldn't you expect those top 25 stories to make some enormous crash when they hit the ground, not to mention a rubble pile of some size - what happened to them? |
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pepik
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| Posted: Sun Nov 11, 2007 8:42 pm Post subject: |
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| Quote: | | OK try this one - the top of WTC2 undoubtedly tilts at a fair angle as it starts to drop. Imagine the side of the building at the far side of the tilt - that is the side with the least mass bearing down on it. Given the lack of mass, how does this side still manage to crumble all the way down to the bottom? |
What lack of mass? There was still plenty of building falling. | Quote: | | Would it not be more inclined to be pulled to the side by the rest of the building as the mass bears down on it. |
According to professors of religion yes, according to engineers no. | Quote: | | Or to summarise, if a building is going to collapse from top to bottom because of the weight of the top section, surely that weight would have to be bearing down equally on all parts of the building? |
According to professors of religion yes, according to engineers no. | Quote: | | And for your bonus question - wouldn't you expect those top 25 stories to make some enormous crash when they hit the ground, not to mention a rubble pile of some size - what happened to them? |
They did leave a pile of rubble. And if you're looking for missing noise, look for the missing sounds of thousands of timed explosives going off.
_________________
"could it be that ww2 and the extermination of jewish people was planned as a way of creating a race of people who it would be difficult to blame for anything, a cover race for the illuminati?" - a quote NOT from the 'controversial theories' section. |
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KP50
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| Posted: Sun Nov 11, 2007 8:56 pm Post subject: |
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| pepik wrote: | | Quote: | | OK try this one - the top of WTC2 undoubtedly tilts at a fair angle as it starts to drop. Imagine the side of the building at the far side of the tilt - that is the side with the least mass bearing down on it. Given the lack of mass, how does this side still manage to crumble all the way down to the bottom? |
What lack of mass? There was still plenty of building falling. |
"There was still plenty of building falling". You must have spent some time thinking about this one. How much of that mass was bearing onto the side of the building furthest from the tilt? Think carefully before you answer and feel free to use diagrams.
| pepik wrote: | | Quote: | | And for your bonus question - wouldn't you expect those top 25 stories to make some enormous crash when they hit the ground, not to mention a rubble pile of some size - what happened to them? |
They did leave a pile of rubble. And if you're looking for missing noise, look for the missing sounds of thousands of timed explosives going off. |
It would be largely intact though wouldn't it? In terms of being smashed rather than turned to dust. Where were the computers from the 105th floor? Or any of the top floors? They should be at the top of the rubble pile and recovered during the search for survivors surely? |
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James C
Major Poster
Joined: 26 Jan 2006
Posts: 1046
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| Posted: Sun Nov 11, 2007 9:15 pm Post subject: |
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| Alex_V wrote: | Gripes about the source I mentioned aside (which seems to have derailed the thread a bit), I would still like to try and understand why the way in which the towers collapsed would be physically impossible. I think it's fair to say that the truth movement has been saying for years now that the collapses defied the basic laws of physics. I would like to establish how they feel this is the case.
James - if you feel the collapse of the towers is more symmetrical than you think is physically possible, you will have to persuade me/us how this is. I know what you mean by the collapse being symmetrical, but I doubt that it was truly symmetrical in precise terms.
Basically, why wouldn't the towers collapse straight down? What evidence is there to suggest otherwise? |
In collapse terms it was symmetrical. The whole structure of each tower was destroyed from top down in one flowing wave. The fact that these were such massive buildings led to an enormous spread of debris at ground level but the overall heap left on the ground fitted mostly into the original WTC site. Now that's impressive for a complete collapse of a high-rise structure. You can research this if you like but I can tell you that no high-rise steel building has ever collapsed this way - period. Only professionally demolished steel buildings have followed such a pattern. On 9/11 of course we had 3 such buildings fall into their own footprint. Now that's truly amazing and I feel little else needs be added to the argument other than to say that the explosions and puffs of smoke visible on the facade much lower down make the case even more convincing (and please don't say these were pressure breakouts)
The problem with the progressive collapse concept at the WTC is that these buildings were truly massive in their engineering. The cores themselves were just enormous skeletal columns and designed to include much redundancy. When the top section of WTC2 began to rotate there was no extra weight on that column overall, although if we assume the core was damaged by the planes then local shifting of weight would have taken place. And yet this column suddenly appeared to break into tiny pieces at a rate only just slower than if a ball had been dropped from the top of the building. So for a structure, i.e. the core, which had succesfully supported the upper section for 30 years, to suddenly fall to pieces in a matter of seconds is really hard to explain. No wonder NIST hasn't bothered, not in public anyway. Now I could accept the progressive collapse scenario more in the case of WTC2 if the upper section was seen to fall down onto the structure below due to failure of the immediate core columns and facade beneath it but that didn't happen. What did happen was the building just gave way to let the upper section drop, but as I say, the facade and core had been supporting that upper section for 3 decades with no apparent problem.
If we look at WTC1 then progressive collapse is an even more difficult explanation given that more of the core was left unaffected especially when one appreciates that the steel became thinner and therefore the towers became lighter the further one went towards the top.
I would suggest that you find some examples of high-rise steel collapses to see how buildings really behave when faced with any sort of structural failure. |
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James C
Major Poster
Joined: 26 Jan 2006
Posts: 1046
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| Posted: Sun Nov 11, 2007 9:21 pm Post subject: |
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| pepik wrote: | | Quote: | | OK try this one - the top of WTC2 undoubtedly tilts at a fair angle as it starts to drop. Imagine the side of the building at the far side of the tilt - that is the side with the least mass bearing down on it. Given the lack of mass, how does this side still manage to crumble all the way down to the bottom? |
What lack of mass? There was still plenty of building falling. | Quote: | | Would it not be more inclined to be pulled to the side by the rest of the building as the mass bears down on it. |
According to professors of religion yes, according to engineers no. | Quote: | | Or to summarise, if a building is going to collapse from top to bottom because of the weight of the top section, surely that weight would have to be bearing down equally on all parts of the building? |
According to professors of religion yes, according to engineers no. | Quote: | | And for your bonus question - wouldn't you expect those top 25 stories to make some enormous crash when they hit the ground, not to mention a rubble pile of some size - what happened to them? |
They did leave a pile of rubble. And if you're looking for missing noise, look for the missing sounds of thousands of timed explosives going off. |
Try watching this video. The explosive sounds at 6.59 mins in are pretty evident I think you'll find. I'd love to hear your explantion for these.
Watch here |
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kbo234
Validated Poster
Joined: 10 Dec 2005
Posts: 2017
Location: Croydon, Surrey
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| Posted: Sun Nov 11, 2007 9:51 pm Post subject: Re: Basic Physics and WTC Collapse |
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| Alex_V wrote: |
Utterly false. NIST's 9 seconds for WTC2 is actually their calculation of when the first exterior panels hit the ground, based on seismic readings and the available footage. It is NOT their calculated time of collapse. |
It is very nearly free-fall speed. So the same generalised arguments still hold. Life is too short for going over and over and over this stuff. The building collapsed through the path of maximum resistance with very little opposition. I have been having these exchanges with various trolls for the last two years so this is my last contribution on the subject.
| Quote: | | Quote: | | 1) Conservation of momentum basically recognises and quantifies the universal fact of the physical world that every 2-year old child instinctively understands (in much the same way they understand that if you drop something it falls to the ground) ........that moving objects are slowed down when they collide with stationary objects. |
Nonsense. Conservation of momentum states that momentum is conserved in collisions. |
I was trying to simplify this for you. Yes, total momentum (mass x velocity) is conserved in any collision provided no external forces are acting. In this case there is an external force (gravity) but the point I made, that the impact of a moving body on a stationary body always results in a loss of velocity or deceleration of the moving body is absolutely true and this is a universal consequence of the principle of conservation of momentum though it is not a statement of the law itself.
| Quote: | | Hence, the impact of floor-on-floor, had such impacts taken place, would certainly have increased the time of collapse. Many estimates of reasonable collapse times have been made, ranging from about 20 to 60 seconds. |
Greening is the *sshole that brought us self-creating thermite from the aluminium, which spontaneously turned into powder, from the crashed plane.
I refuse to read another word of that man's laughable gibberish.
| Quote: | | Well worth a read, particularly as it blows most of what you have said here out of the water. |
Enough of this w*nk. |
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Alex_V
Wrecker
Joined: 24 Sep 2007
Posts: 515
Location: London, England
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| Posted: Mon Nov 12, 2007 1:51 am Post subject: |
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| James C wrote: | ...Now I could accept the progressive collapse scenario more in the case of WTC2 if the upper section was seen to fall down onto the structure below due to failure of the immediate core columns and facade beneath it but that didn't happen. What did happen was the building just gave way to let the upper section drop, but as I say, the facade and core had been supporting that upper section for 3 decades with no apparent problem.
If we look at WTC1 then progressive collapse is an even more difficult explanation given that more of the core was left unaffected especially when one appreciates that the steel became thinner and therefore the towers became lighter the further one went towards the top.
I would suggest that you find some examples of high-rise steel collapses to see how buildings really behave when faced with any sort of structural failure. |
I'm not sure what there actually is to respond to here. For 30 years the building stood up, thus proving that it cannot then collapse in these circumstances?
I don't see how stating that no buildings have been hit by jets like this before informs our understanding of why the buildings could or couldn't collapse in certain ways after the impacts and fire. If we had lots of examples to draw on of jets hitting buildings, and the different ways in which they had collapsed, then we would have some evidence to draw on. But just saying "this had never happened before" is just not much of an argument IMO.
Greening, Bazant and others suggest that, taken on a floor by floor basis, they had no ability whatsoever to resist the force of the ever-increasing mass of debris falling from above. I would be happy to consider scientific arguments to counter that. But I cannot just accept "isn't it suspicious that these buildings collapsed", which seems to be the main thrust of your argument here.
There are still no arguments here why the WTC collapses couldn't be straight down once initiated, at a near free-fall speed. |
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Alex_V
Wrecker
Joined: 24 Sep 2007
Posts: 515
Location: London, England
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| Posted: Mon Nov 12, 2007 2:36 am Post subject: Re: Basic Physics and WTC Collapse |
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| Quote: | | It is very nearly free-fall speed. So the same generalised arguments still hold. Life is too short for going over and over and over this stuff. The building collapsed through the path of maximum resistance with very little opposition. I have been having these exchanges with various trolls for the last two years so this is my last contribution on the subject. |
The same arguments do not hold at all in my opinion. In your original comments you claimed the OT was for a faster-than-freefall collapse, which is basically just a lie. You then made further attacks on that basis. I'm surprised over your 2 years of going over the material that you would still make that basic mistake.
The buildings didn't collapse through the path of maximum resistance at all - would you care to back this up?
| Quote: | | I was trying to simplify this for you. Yes, total momentum (mass x velocity) is conserved in any collision provided no external forces are acting. In this case there is an external force (gravity) but the point I made, that the impact of a moving body on a stationary body always results in a loss of velocity or deceleration of the moving body is absolutely true and this is a universal consequence of the principle of conservation of momentum though it is not a statement of the law itself. |
But of course this is an irrelevance without figures, as I'm sure many 11-year-olds also know. So for the truth movement to claim that the collapse defies physics without any reference to the actual forces at work is disingenuous at best.
And of course, the concept your refer to makes it totally clear without any doubt that global collapse is inevitable once the first floor gives way, as an increased mass would in theory be falling from a (decelerated) moving start and hence at a greater velocity when it hits the next floor down. So the idea of some in the truth movement that the collapse would somehow peter out once it had begun is utter rubbish.
| Quote: | Greening is the *sshole that brought us self-creating thermite from the aluminium, which spontaneously turned into powder, from the crashed plane.
I refuse to read another word of that man's laughable gibberish. |
http://www.911myths.com/WTCTHERM.pdf - for reference. I'm no particular fan of Greening - his attacks on NIST seem to me to be quite petty. But at least he provides his sources and lays his science out for all to see, unlike some.
| Quote: | | Enough of this w*nk. |
If that's a resignation, I accept your terms - you don't really seem to have much of a grasp of what you're talking about. |
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Bushwacker
Relentless Limpet Shill
Joined: 07 Sep 2006
Posts: 1628
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| Posted: Mon Nov 12, 2007 11:09 am Post subject: |
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| James C wrote: | | Bushwacker wrote: | | James C wrote: |
The top section of WTC2 fell into the dust cloud, it didn't create it. The top section started to rotate only as the explosions (above and below that section) occured but then it stopped rotating and dropped vertically. Why?, because clearly the structure it was attached to, below itself, had fallen away - otherwise it would have continued to rotate until dropping off. The rest of the building (as in the case of WTC1 and WTC7) remained a symmetrical collapse or are you disputing that?
So Greening puts together a set of calculations and assumptions without even reflecting on how the building could have fallen like that. If he had stopped to consider this issue he would, just like NIST, have stopped before wasting his time. His paper is pointless.
And who said the dust cloud included steel? Have I ever said that? Of course, one has to question where the large amount of dust came from which was ejected as the top of WTC2 (and WTC1) started to fall. |
Ah, imaginary explosions - no doubt they explain a lot for you, although it is the first time I have heard it suggested that there were explosions above the top section. But what explains your belief that the top section of WTC2, obviously weighing thousands of tons, and rotating, is going to stop rotating because the structure below it had fallen away? That makes no sense, does it?
You said ".........which suggests that each floor fell to dust during motion. In other words, there just wasn't the momentum there from above to have destroyed that which was below." You either meant floor as in storey, as I took it, which meant that the steel turned to dust as well, a la Judy Woods and her beam weapon, or you meant literally just the floor, the main weight of the building in the steel structure not being included, in which case your remark about the momentum makes no sense. |
You have a terrible memory. Last year, October if I recall correctly, we discussed in the critics corner the video of WTC2 collapsing. It was this video and if you watch carefully you'll see flashes and puffs of smoke on the top section starting from the nearside corner as it falls. The critics put it down to breaking glass. I say the flashes are explosions. Either way, this issue should not be new to you so why claim that it is. Please try and keep up.
As for your last comment, you appear to be making something out of nothing. Are you really that desperate? |
So when you say there were explosions above the top section, you mean there were explosives on the top section, you cannot explain why the top section should stop rotating because the structure below it has fallen away, and the you cannot explain your comment about each floor falling to dust, because whichever way one takes it, it makes no sense.
You really should try to think about what you are posting before you press "submit" because at the moment what you are saying comes out as absolute nonsense, and an embarassment to you. |
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Bushwacker
Relentless Limpet Shill
Joined: 07 Sep 2006
Posts: 1628
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| Posted: Mon Nov 12, 2007 11:19 am Post subject: |
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| James C wrote: |
I would suggest that you find some examples of high-rise steel collapses to see how buildings really behave when faced with any sort of structural failure. |
If you remember you failed before to find any examples of buildings collapsing in the way you think they should, despite your earlier boast that there were many such instances.
Can you really see no difference between the structure supporting the static load of the upper floors, as it had for 30 years, and the dynamic load of the same mass dropped on to it when the fire floors gave way? |
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landless peasant
Moderate Poster
Joined: 15 Aug 2006
Posts: 137
Location: southend essex
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| Posted: Mon Nov 12, 2007 12:48 pm Post subject: |
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Alex_V
Basically, why wouldn't the towers collapse straight down? What evidence is there to suggest otherwise?
LOL and we get called the loons... Basically, a falling object will always fall to the path of lest resistance, Not thru thousands of tonnes of steel. A building will only come straight down if that resistance is removed. If resistance is not removed it won't. It will take the path of lest resistance. Basically
Try this link http://www.911blogger.com/node/10025
Richard Gage, AIA, Architect - "How The Towers Fell" - Complete 2 Hour Presentation
NOT PERFECT BUT A GOOD PLACE TO START  GL |
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Alex_V
Wrecker
Joined: 24 Sep 2007
Posts: 515
Location: London, England
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| Posted: Mon Nov 12, 2007 2:30 pm Post subject: |
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| paulsouthend wrote: | | LOL and we get called the loons... Basically, a falling object will always fall to the path of lest resistance, Not thru thousands of tonnes of steel. A building will only come straight down if that resistance is removed. If resistance is not removed it won't. It will take the path of lest resistance. Basically |
I understand the concept of a path of least resistance, but how does it really apply to the collapse of the twin towers?
Let's take that moment in the collapse scenario where the 12 (or 24) floors fall onto the first floor below. Are you suggesting that rather than hitting the floor below the mass of debris would rather search around it for a less resistent route? Obviously it cannot because it has its own momentum - to do anything but go forward (down) would be impossible. Surely we all agree it has to hit the floor below.
Now IF the floor doesn't provide enough resistance to stop or deflect the mass of debris, it JOINS the debris and goes in which direction? That's right, DOWN again. So a (theoretically) larger mass of debris continues to travel down, accelerating to a greater velocity by the time it hits the next floor. We have the same situation again (only moreso) - will this greater mass of debris defy its own greater momentum or hit the floor below?
The path of least resistance, therefore is straight down, because to follow any other path would be to resist the downwards momentum, essentially the forces of gravity.
I find your assertion similar to suggesting that a bullet would never hit its victim, because rather than penetrate the skin it would look for a 'less resistant' path around the victim's body. Inanimate objects do not have minds of their own - they react perfectly to the forces placed upon them. |
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James C
Major Poster
Joined: 26 Jan 2006
Posts: 1046
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| Posted: Mon Nov 12, 2007 6:28 pm Post subject: |
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| Bushwacker wrote: | | James C wrote: |
I would suggest that you find some examples of high-rise steel collapses to see how buildings really behave when faced with any sort of structural failure. |
If you remember you failed before to find any examples of buildings collapsing in the way you think they should, despite your earlier boast that there were many such instances.
Can you really see no difference between the structure supporting the static load of the upper floors, as it had for 30 years, and the dynamic load of the same mass dropped on to it when the fire floors gave way? |
And can you not see that the upper section does not fall onto the lower section. Where is the dynamic load? |
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