But.....if the building is hit in the middle, like the WTC was, and the steel is weakened by fire, like it was, and if the floor supports collapse, like they did, you get a domino effect, one floor hits the next floor, which causes that floor to fall, and it keeps happening, faster and faster every time.jonsimon wrote:
Propane blew apart skyscrapers? Because your average 4 story building is drastically different from a skyscraper. Skyscrapers are better imagined upside-down. They are suspended by the foundation, the only way to knock down a skyscraper the way the towers fell is to attack the foundation. Did the planes hit the bottom of the buildings or the top? The top. They couldn't have knocked down those buildings. For another analogy, think of the towers as two trees. If you take to the top of a tree with an axe, it will never fall. Chop away at the bottom and it falls. Not exactly the same as a skyscraper, but it gets the point across.psychotoxic187 wrote:
Yes, all the stuff in the building caught fire. It will burn from an explosion. Look at the story here of Faulk corporation. Propane blew apart buildings with nothing standing left. The impact alone from the jet would of weakened the structural integrity, then all it takes is one suppost beam to fail, and the rest will follow. If one floor fails, and crashes down, the lower floors will not be able to sustain further pressure from the crashing down.jonsimon wrote:
Dude, to burn anything you need heat and time. If any kind of starter burns all at once, you don't develop a fire. You can wave wood through a fire without it catching, and anyone who has made a campfire knows that the conditions required are very specific. Nearly all the limited supply of fuel burst into flames at the same time, it just isn't physically possible that flames took that building down. (Esspecially since tenfold larger blazes have burned for hours, one even a day long, and the worst damage was the partial collapse of a few floors at the top.)
Bottom line, those two planes could not have taken down those buildings, so something else had to.
The lead structural engineer reflects on the rise and fall of the World Trade Center towers.
It appears that about 25,000 people safely exited the buildings, almost all of them from below the impact floors; almost everyone above the impact floors perished, either from the impact and fire or from the subsequent collapse. The structures of the buildings were heroic in some ways but less so in others. The buildings survived the impact of the Boeing 767 aircraft, an impact very much greater than had been contemplated in our design (a slow-flying Boeing 707 lost in the fog and seeking a landing field). Therefore, the robustness of the towers was exemplary. At the same time, the fires raging in the inner reaches of the buildings undermined their strength. In time, the unimaginable happened . . . wounded by the impact of the aircraft and bleeding from the fires, both of the towers of the World Trade Center collapsed.
http://www.nae.edu/nae/bridgecom.nsf/we … enDocument
http://www.public-action.com/911/jmcm/clifton.pdf <-- Exactly why they collapsed. It's only 13 pages, you can handle reading it.
Since someone mentioned loose change, make sure you read the subtitles and watch the theories get destroyed here.
[google]http://video.google.com/videoplay?docid=-3214024953129565561&hl=en-CA[/google]
It appears that about 25,000 people safely exited the buildings, almost all of them from below the impact floors; almost everyone above the impact floors perished, either from the impact and fire or from the subsequent collapse. The structures of the buildings were heroic in some ways but less so in others. The buildings survived the impact of the Boeing 767 aircraft, an impact very much greater than had been contemplated in our design (a slow-flying Boeing 707 lost in the fog and seeking a landing field). Therefore, the robustness of the towers was exemplary. At the same time, the fires raging in the inner reaches of the buildings undermined their strength. In time, the unimaginable happened . . . wounded by the impact of the aircraft and bleeding from the fires, both of the towers of the World Trade Center collapsed.
http://www.nae.edu/nae/bridgecom.nsf/we … enDocument
http://www.public-action.com/911/jmcm/clifton.pdf <-- Exactly why they collapsed. It's only 13 pages, you can handle reading it.
Since someone mentioned loose change, make sure you read the subtitles and watch the theories get destroyed here.
[google]http://video.google.com/videoplay?docid=-3214024953129565561&hl=en-CA[/google]
Xbone Stormsurgezz
No. Grow up.LawJik wrote:
The World Trade Towers, were demolished by using Thermate, it is a known, discovered, fact.
Don't overuse the word fact, plz. Thousands of people use that word way to much when it comes to 911 theories and each time its based on nothing more then some 'expert' talking about stuff that the people watching it don't even understand. This is a theory just like many others. Out of all the theories it's the most likely one, also the only one which I believe, but don't stamp a fact on it just because it seems to be so likely.LawJik wrote:
The World Trade Towers, were demolished by using Thermate, it is a known, discovered, fact.
About 6 months after the 911 attacks I had to do a paper for school, I did it about the WTC, including the '93 attack and the '01 attack. I did my own research at the time, 6 months after the attacks these kinds of video's didn't exist yet and most of the people still bought the cover up story. I only had a hand full of web pages to give me pictures and descriptions on the events. Eventually I got a hold of the official press release and when I read it I was stunned to know that so many people believed it word for word. Because everyone who has even read the official statement should just see that it DOES NOT MAKE SENSE. And I mean... AT ALL!
One of the first things I figured out when doing my own research without reading up expert opinions, was that it was physically impossible for a pancake collapse to bring down the structure in under 10 seconds. There's just no way because at least 6 stories would have had to collapse in under a second at a time to even come close to a 10 second collapse. And that just doesn't happen... you don't need to be a structural engineer to realize that.
Steel doesn't melt at the temperatures up there, but it does weaken it yes. The steel would indeed be to weak to support the stories above the point of impact, but think about this: The collapse was perfect. All 4 corners would have had to be equaly as weak for the tower to collapse like that. This also, was not possible. Not in the North Tower, but especially not in the South Tower because the plane came in at an angle and most of the fuel burned up in the ball of fire. The other 3 corners of the South tower should have been completely intact and unharmed as well as the core of the building. Yet for some reason the South Tower collapsed first because all 4 corners and the core all weakened at the exact same rate while only one corner was actually destroyed? I hope people can see that something like that does not add up.
I could go on and on and on giving you logical explainations to the entire event, but I'm not going to. My point is this: All these videos that have been popping up the last 6 years have all had their share of experts on the team. They are all trained in the same expertise yet they all say something completely different. And it's much easier to pick apart an anti conspiracy tape then one that supports it.
Why are all these anti conspiracy people out there? Because imagine what would happen if the collapse of the WTC did turn out to be planned and controlled. Some people won't even consider it being possible. No-one is saying the US goverment had anything to do with it, okay some people are, but looking at the facts on the table (perfect demolition, clean cut steel beems, heard explosions before the collapse, ect) don't you have to at least admit things look a little bit fishy? And when you do finaly figure that out, ask yourself why the government would send out a bullshit cover up story like they did if they knew nothing about 'it' (assuming there is an 'it').
@ Topic Starter: Do your own research into things before stating that others are wrong just because this tape you saw stated otherwise. You are not entitled to an opinion if you get it from watching a tape and not even knowing what these people are talking about or if they are even right for that matter. Do your own research before claiming anything.
Tiger
G Charles Clifton, Structural Engineer.
Each tower was hit by a Boeing 767. The impact on the North tower was near
the center of the North face at around the 95th storey, with the plane hitting the
side of the building square on and flying level. The impact on the South tower
was some 15 storeys lower, with the plane hitting the South face near the
South East corner and impacting at an angle to the face of the tower. Fig 2
shows the impact directions and Fig 8 shows the plane about to hit the South
Tower.
The potential force of the impact from each plane can be approximately
calculated and the figures are very large. The weight of each plane would
have been approximately 150 tonnes, according to the media reports and
Boeing data on this type of plane. The plane would have been traveling at
around 800 kms/hour at impact. This gives a momentum of
150x800/3.6=33,333 tonnes.m/sec. If the plane was arrested by the building
in 1.5 seconds, which is a reasonable estimate based on the video footage,
then the force exerted on the building is the momentum/time to arrest, ie
Force=33,333/1.5=22,222kN. To put that in perspective, the ultimate limit
state design wind pressure over the entire height of the building is 220 kg/m2.
This gives a ULS wind force on one face of the building of 58, 400 kN. Thus
the potential force of impact from the plane is over 1/3 of the design ultimate
limit state wind load on the building! Especially in the case of the North Tower,
not much of the plane was ejected from the building, so it is reasonable to
assume the most of that potential force was absorbed by the building. Also
the above calculation also does not take into account any additional force
generated inside the building from blast loading due to, for example,
exploding jet fuel.
Having done this calculation it is more easy to understand what our eyes
showed us – namely the planes slicing through the perimeter frames “ like a
knife through butter” as one reporter has stated. I contend that, having
penetrated the perimeter frames the planes would have done much more that
just stripping the fire protection off the columns as has been surmised by
some commentators. The effect would have been to completely shatter and
eliminate large areas of floor slab and many of the internal supporting
columns, thereby immediately destroying much of the vertical load carrying
system and leaving the rest vulnerable to any subsequent fire attack. This
impact damage - not the severity of the fire – I contend is the principal cause
of the ultimate collapse. However the nature and position of impact was
different in each case and this led to different effects on each tower, with
different collapse mechanisms. These effects are now discussed in as much
detail as is possible based on the known information.
Figure 9
Fig 9 shows the view looking into the impact hole. Given that the floor slabs
are at 3.66 m centers and the façade column centers are at 1.03 metre
centers with façade window widths of only 0.48 m, the number of façade
columns and perimeter beams severed by the airplane in its passage though
the perimeter frame is considerable. From the major damage to the side
opposite the impact it is also apparent that much of the airplane would have
passed through the core. It is likely that the impact destroyed most of the
floors, at least on the impact side, and the core on at least three levels,
removing many of the core supporting columns, at least on the North side of
the core, and leaving the remainder buckled and stripped of their passive fire
protection. This would have caused the floors above the impact level to sag
downwards in the center, with the gravity columns above the impact region
now acting as tension ties between each of the upper floors, through to the
top floor. Each upper floor would now have had to be at least partially
supported off the perimeter frame. HERA has developed a method ( based on
UK fire research) allowing the design of unprotected secondary beams in
composite floor systems by using the dependable inelastic reserve of strength
from a region of floor slab supported around its perimeter. I have applied this
in a very approximate manner to a typical WTC floor slab supported off only
the perimeter frame and the result shows that this is just about possible with
regard to the membrane capacity of the floor system, but not possible in terms
of the vertical load carrying capacity of the connection between the floors and
the perimeter frame. As the vertical load carrying capacity of the core
diminished, requiring more load to be transferred from the floors to the
perimeter frames, the mode of failure would have most likely been failure of
this connection, leading to floor collapse.
I contend that, immediately following the impact, the core region of all the
floors above the impact region would have sagged downwards due to the loss
of vertical support in the core region. This sag would have progressively
grown as the fire and ongoing yielding of the remaining damaged core
columns reduced the core vertical load carrying capacity. This would have
placed severe overstress on the connection between floor and perimeter
frame around each floor at every level, with the greatest effect at the top floor,
due to the core columns interconnecting each floor above the impact region
now acting as tension ties. This would also have put extra vertical load on the
perimeter frames, however these are sized to resist the lateral loading and
would have had more than sufficient capacity to resist this extra load,
especially as it would have distributed itself symmetrically around the
perimeter frames. <-- Why it appeared to fall straight down.
The sagging of the core region on the upper floors could have been the
reason for a phonecall from the upper levels shortly after the impact saying
that the building was breaking up. The sagging around the core and the
impact damage would also have made the stairs impassible through the
impact region, cutting off escape from the upper floors.
The strength, stiffness and redundancy of the perimeter frames would also
have been more than adequate to redistribute vertical load around the
severed members on the impact side, thus preserving the intergrity of these
frames above the impact region.
The likely influence of the fire in the time from impact to collapse would have
been to progressively weaken the residual vertical load carrying capacity from
the remaining core columns, increasing the need for slab panel action from
the floor slabs above the impact region back to the perimeter frame. This
would have been transmitted up through the floors above the impact region
through the tension tie effect from the core columns, increasing the severity
Finally, it is likely that the interconnection between one or more floors and the
perimeter frame failed at or near the top of the building. This would have
resulted in the immediate collapse of these floors. From the video footage this
collapse appeared to occur uniformly around the building and spread very
rapidly down to the floor above the impact region. That region then pancaked
causing a brief gout of flame to be expelled most noticeably from around the
South and East sides as the areas within the impact region still on fire
collapsed.
The collapse then continued down the building, with the floors pancaking
leaving the perimeter frames briefly standing unsupported until they too
collapsed. The effect of the floors pancaking nearly straight down inside the
perimeter frames lead to the North tower effectively imploding, with some
sections of the perimeter frame remaining standing unsupported for a few
seconds before collapsing. This is seen from a number of video footages and
pictures, including the collapse sequence shown in Fig 10.
Figure 10
Considered Effect of Impact on South Tower.
At 9.03 am the plane impacted the South side of the south tower towards the
South East corner. It struck the building at an angle across that corner and on
a slight downwards heading, as shown in Fig.2. The plane passed into the
building and then exploded out of the adjacent East side, causing a large
fireball to erupt from both the entry and exit sides adjacent to the South East
corner. Fig. 8 shows the plane immediately before impact and Fig 11 shows
the expanding fireball erupting from both sides of the building.
In contrast to the North Tower impact, in the case of the South Tower only
one corner of the core would have been directly in front of the plane’s path
through the building, along with the floor slabs over several levels in the South
East corner. It is likely that the initial impact destroyed all the floor slabs in that
corner over at least four levels and maybe over as many as six. It would have
also severely damaged the South East corner core, removing an unknown
number of columns there, buckling many more and destroying most of the
Collapse of the World Trade Center Towers
core walls ( which are drywall construction). We do know that at least one
stairwell in the core remained intact after the impact, as there were reported to
be survivors from the floors above the impact floor who must have had access
to an intact stairwell to escape.
Immediately after the impact the perimeter frame in the South East corner
would have been severely weakened, being reduced to an unknown number
of intact box columns in towards that corner on each of the two sides.
However, these columns would have lost the lateral support from the floor
slabs over many levels and would have had to function as isolated columns
spanning multiple storey heights. They would likely have suffered blast
damage and loss of alignment, however immediately following the impact they
still retained sufficient compression capacity to resist their share of the loads
from the 30 or so floors above the impact region.
Figure 11 Figure 12
The fires started by the impact would have then progressively weakened the
vertical load carrying capacity of the remaining core, causing progressively
more load to have to be carried by the perimeter frame system. In my opinion,
based on the footage taken of the building over that time, the fire would have
had little impact on the strength and stiffness of the perimeter frames, even in
the damaged corner. The stiffness of this system above the impact region
would have distributed this load approximately uniformly around the perimeter
frames, increasing the loading on these frames through the impact region,
including on the residual columns in the damaged corner.
Finally the combination of increasing compression load on these damaged
columns, with second order effects from this load acting on the buckled shape
of these columns over their unsupported length, would have caused their
collapse. This collapse would have initiated in the damaged corner and
spread rapidly over the impact region, causing the tower above to fail by
toppling sideways with the floors above the impact region momentarily in an
intact condition. This stage of the collapse is shown in Fig. 12.
Collapse of the World Trade Center Towers Rev11.doc
However, even with the top floors toppling sideways, sufficient material would
have impacted straight down on the floors below the impact region to have
caused these to start to pancake downwards, leading to the tower below the
impact region collapsing in much the same manner as the North tower.
With both towers, the forces created by the falling floors above on the floors
below would have been orders of magnitude greater than the
Each tower was hit by a Boeing 767. The impact on the North tower was near
the center of the North face at around the 95th storey, with the plane hitting the
side of the building square on and flying level. The impact on the South tower
was some 15 storeys lower, with the plane hitting the South face near the
South East corner and impacting at an angle to the face of the tower. Fig 2
shows the impact directions and Fig 8 shows the plane about to hit the South
Tower.
The potential force of the impact from each plane can be approximately
calculated and the figures are very large. The weight of each plane would
have been approximately 150 tonnes, according to the media reports and
Boeing data on this type of plane. The plane would have been traveling at
around 800 kms/hour at impact. This gives a momentum of
150x800/3.6=33,333 tonnes.m/sec. If the plane was arrested by the building
in 1.5 seconds, which is a reasonable estimate based on the video footage,
then the force exerted on the building is the momentum/time to arrest, ie
Force=33,333/1.5=22,222kN. To put that in perspective, the ultimate limit
state design wind pressure over the entire height of the building is 220 kg/m2.
This gives a ULS wind force on one face of the building of 58, 400 kN. Thus
the potential force of impact from the plane is over 1/3 of the design ultimate
limit state wind load on the building! Especially in the case of the North Tower,
not much of the plane was ejected from the building, so it is reasonable to
assume the most of that potential force was absorbed by the building. Also
the above calculation also does not take into account any additional force
generated inside the building from blast loading due to, for example,
exploding jet fuel.
Having done this calculation it is more easy to understand what our eyes
showed us – namely the planes slicing through the perimeter frames “ like a
knife through butter” as one reporter has stated. I contend that, having
penetrated the perimeter frames the planes would have done much more that
just stripping the fire protection off the columns as has been surmised by
some commentators. The effect would have been to completely shatter and
eliminate large areas of floor slab and many of the internal supporting
columns, thereby immediately destroying much of the vertical load carrying
system and leaving the rest vulnerable to any subsequent fire attack. This
impact damage - not the severity of the fire – I contend is the principal cause
of the ultimate collapse. However the nature and position of impact was
different in each case and this led to different effects on each tower, with
different collapse mechanisms. These effects are now discussed in as much
detail as is possible based on the known information.
Figure 9
Fig 9 shows the view looking into the impact hole. Given that the floor slabs
are at 3.66 m centers and the façade column centers are at 1.03 metre
centers with façade window widths of only 0.48 m, the number of façade
columns and perimeter beams severed by the airplane in its passage though
the perimeter frame is considerable. From the major damage to the side
opposite the impact it is also apparent that much of the airplane would have
passed through the core. It is likely that the impact destroyed most of the
floors, at least on the impact side, and the core on at least three levels,
removing many of the core supporting columns, at least on the North side of
the core, and leaving the remainder buckled and stripped of their passive fire
protection. This would have caused the floors above the impact level to sag
downwards in the center, with the gravity columns above the impact region
now acting as tension ties between each of the upper floors, through to the
top floor. Each upper floor would now have had to be at least partially
supported off the perimeter frame. HERA has developed a method ( based on
UK fire research) allowing the design of unprotected secondary beams in
composite floor systems by using the dependable inelastic reserve of strength
from a region of floor slab supported around its perimeter. I have applied this
in a very approximate manner to a typical WTC floor slab supported off only
the perimeter frame and the result shows that this is just about possible with
regard to the membrane capacity of the floor system, but not possible in terms
of the vertical load carrying capacity of the connection between the floors and
the perimeter frame. As the vertical load carrying capacity of the core
diminished, requiring more load to be transferred from the floors to the
perimeter frames, the mode of failure would have most likely been failure of
this connection, leading to floor collapse.
I contend that, immediately following the impact, the core region of all the
floors above the impact region would have sagged downwards due to the loss
of vertical support in the core region. This sag would have progressively
grown as the fire and ongoing yielding of the remaining damaged core
columns reduced the core vertical load carrying capacity. This would have
placed severe overstress on the connection between floor and perimeter
frame around each floor at every level, with the greatest effect at the top floor,
due to the core columns interconnecting each floor above the impact region
now acting as tension ties. This would also have put extra vertical load on the
perimeter frames, however these are sized to resist the lateral loading and
would have had more than sufficient capacity to resist this extra load,
especially as it would have distributed itself symmetrically around the
perimeter frames. <-- Why it appeared to fall straight down.
The sagging of the core region on the upper floors could have been the
reason for a phonecall from the upper levels shortly after the impact saying
that the building was breaking up. The sagging around the core and the
impact damage would also have made the stairs impassible through the
impact region, cutting off escape from the upper floors.
The strength, stiffness and redundancy of the perimeter frames would also
have been more than adequate to redistribute vertical load around the
severed members on the impact side, thus preserving the intergrity of these
frames above the impact region.
The likely influence of the fire in the time from impact to collapse would have
been to progressively weaken the residual vertical load carrying capacity from
the remaining core columns, increasing the need for slab panel action from
the floor slabs above the impact region back to the perimeter frame. This
would have been transmitted up through the floors above the impact region
through the tension tie effect from the core columns, increasing the severity
Finally, it is likely that the interconnection between one or more floors and the
perimeter frame failed at or near the top of the building. This would have
resulted in the immediate collapse of these floors. From the video footage this
collapse appeared to occur uniformly around the building and spread very
rapidly down to the floor above the impact region. That region then pancaked
causing a brief gout of flame to be expelled most noticeably from around the
South and East sides as the areas within the impact region still on fire
collapsed.
The collapse then continued down the building, with the floors pancaking
leaving the perimeter frames briefly standing unsupported until they too
collapsed. The effect of the floors pancaking nearly straight down inside the
perimeter frames lead to the North tower effectively imploding, with some
sections of the perimeter frame remaining standing unsupported for a few
seconds before collapsing. This is seen from a number of video footages and
pictures, including the collapse sequence shown in Fig 10.
Figure 10
Considered Effect of Impact on South Tower.
At 9.03 am the plane impacted the South side of the south tower towards the
South East corner. It struck the building at an angle across that corner and on
a slight downwards heading, as shown in Fig.2. The plane passed into the
building and then exploded out of the adjacent East side, causing a large
fireball to erupt from both the entry and exit sides adjacent to the South East
corner. Fig. 8 shows the plane immediately before impact and Fig 11 shows
the expanding fireball erupting from both sides of the building.
In contrast to the North Tower impact, in the case of the South Tower only
one corner of the core would have been directly in front of the plane’s path
through the building, along with the floor slabs over several levels in the South
East corner. It is likely that the initial impact destroyed all the floor slabs in that
corner over at least four levels and maybe over as many as six. It would have
also severely damaged the South East corner core, removing an unknown
number of columns there, buckling many more and destroying most of the
Collapse of the World Trade Center Towers
core walls ( which are drywall construction). We do know that at least one
stairwell in the core remained intact after the impact, as there were reported to
be survivors from the floors above the impact floor who must have had access
to an intact stairwell to escape.
Immediately after the impact the perimeter frame in the South East corner
would have been severely weakened, being reduced to an unknown number
of intact box columns in towards that corner on each of the two sides.
However, these columns would have lost the lateral support from the floor
slabs over many levels and would have had to function as isolated columns
spanning multiple storey heights. They would likely have suffered blast
damage and loss of alignment, however immediately following the impact they
still retained sufficient compression capacity to resist their share of the loads
from the 30 or so floors above the impact region.
Figure 11 Figure 12
The fires started by the impact would have then progressively weakened the
vertical load carrying capacity of the remaining core, causing progressively
more load to have to be carried by the perimeter frame system. In my opinion,
based on the footage taken of the building over that time, the fire would have
had little impact on the strength and stiffness of the perimeter frames, even in
the damaged corner. The stiffness of this system above the impact region
would have distributed this load approximately uniformly around the perimeter
frames, increasing the loading on these frames through the impact region,
including on the residual columns in the damaged corner.
Finally the combination of increasing compression load on these damaged
columns, with second order effects from this load acting on the buckled shape
of these columns over their unsupported length, would have caused their
collapse. This collapse would have initiated in the damaged corner and
spread rapidly over the impact region, causing the tower above to fail by
toppling sideways with the floors above the impact region momentarily in an
intact condition. This stage of the collapse is shown in Fig. 12.
Collapse of the World Trade Center Towers Rev11.doc
However, even with the top floors toppling sideways, sufficient material would
have impacted straight down on the floors below the impact region to have
caused these to start to pancake downwards, leading to the tower below the
impact region collapsing in much the same manner as the North tower.
With both towers, the forces created by the falling floors above on the floors
below would have been orders of magnitude greater than the
Last edited by Kmarion (2007-03-04 11:40:07)
Xbone Stormsurgezz
----------------------------> actual arguement
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sub-arguement becomes the entire discussion: arguement becomes pointless
welcome to D&ST
\
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sub-arguement becomes the entire discussion: arguement becomes pointless
welcome to D&ST
Inevitable... it will switch to wmd's soon, then JFK.SargeV1.4 wrote:
----------------------------> actual arguement
\
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\/
sub-arguement becomes the entire discussion: arguement becomes pointless
welcome to D&ST
Xbone Stormsurgezz
Yea that's a nice copy and paste you did there, but all I see in that lengthy piece of text is a lot of fancy terms that mean hardly anything to a normal person. I bet you don't even know what he's talking about half that article. In short he's saying that the plane destroyed the core and some support colloms but that the remaining beams divided the weight which is why it collapsed in such a nice way.Kmarion wrote:
G Charles Clifton, Structural Engineer.
If this was the case then shouldn't the entire top half of the South Tower have plunged down because it tipped over at the start of the collapse? The logic this theory follows would have made it impossible for all three structures to have come down to ground level. The collapse would have stopped 20 stories up and the debris would have scattered all over the financial district because eventually rubble would tip over to one side and drag the rest of the collapse that way, leaving whatever is underneath unharmed.
And on a completely different note, this article points the finger at destroyed beams by the plane. If that was the case for both WTC 1 and 2 to collapse, then what happened to WTC 7? I didn't see a plane destroy any beams there... nor did it have to distribute the weight because it was missing a support beam...
Exactly what was the original argument? "All conspiracy theories are stupid, I'm right and you are all sooooo wrong!"?----------------------------> actual arguement
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sub-arguement becomes the entire discussion: arguement becomes pointless
Tiger
Last edited by TigerXtrm (2007-03-04 12:27:28)
Why the towers fell: Two theories
By William Rice
Posted March 1, 2007
Having worked on structural steel buildings as a civil engineer in the era when the Twin Towers were designed and constructed, I found some disturbing discrepancies and omissions concerning their collapse on 9/11.
I was particularly interested in the two PBS documentaries that explained the prevailing theories as determined by two government agencies, FEMA and NIST (National Institute of Science and Technology). The first (2002) PBS documentary, Why the Towers Fell, discussed how the floor truss connectors failed and caused a “progressive pancake collapse.”
The subsequent 2006 repackaged documentary Building on Ground Zero explained that the connectors held, but that the columns failed, which is also unlikely. Without mentioning the word “concrete,” the latter documentary compared the three-second collapse of the concrete Oklahoma City Murrah Federal Building with that of the Twin Towers that were of structural steel. The collapse of a concrete-framed building cannot be compared with that of a structural steel-framed building.
Since neither documentary addressed many of the pertinent facts, I took the time to review available material, combine it with scientific and historic facts, and submit the following two theories for consideration.
The prevailing theory
The prevailing theory for the collapse of the 110-story, award-winning Twin Towers is that when jetliners flew into the 95th and 80th floors of the North and South Towers respectively, they severed several of each building’s columns and weakened other columns with the burning of jet fuel/kerosene (and office combustibles).
However, unlike concrete buildings, structural steel buildings redistribute the stress when several columns are removed and the undamaged structural framework acts as a truss network to bridge over the missing columns.
After the 1993 car bomb explosion destroyed columns in the North Tower, John Skilling, the head structural engineer for the Twin Towers, was asked about an airplane strike. He explained that the Twin Towers were originally designed to withstand the impact of a Boeing 707 (similar in size to the Boeing 767). He went on to say that there would be a horrendous fire from the jet fuel, but “the building structure would still be there.”
The 10,000 gallons of jet fuel (half capacity) in each jetliner did cause horrendous fires over several floors, but it would not cause the steel members to melt or even lose sufficient strength to cause a collapse. This is because the short-duration jet fuel fires and office combustible fires cannot create (or transmit to the steel) temperatures hot enough. If a structural steel building could collapse because of fire, it would do so slowly as the various steel members gradually relinquished their structural strength. However, in the 100-year history of structural-steel framed buildings, there is no evidence of any structural steel framed building having collapsed because of fire.
Let’s assume the unlikelihood that these fires could weaken all of the columns to the same degree of heat intensity and thus remove their structural strength equally over the entire floor, or floors, in order to cause the top 30-floor building segment (South Tower WTC #2) to drop vertically and evenly onto the supporting 79th floor. The 30 floors from above would then combine with the 79th floor and fall onto the next level down (78th floor) crushing its columns evenly and so on down into the seven levels below the street level.
The interesting fact is that each of these 110-story Twin Towers fell upon itself in about ten seconds at nearly free-fall speed. This violates Newton’s Law of Conservation of Momentum that would require that as the stationary inertia of each floor is overcome by being hit, the mass (weight) increases and the free-fall speed decreases.
Even if Newton’s Law is ignored, the prevailing theory would have us believe that each of the Twin Towers inexplicably collapsed upon itself crushing all 287 massive columns on each floor while maintaining a free-fall speed as if the 100,000, or more, tons of supporting structural-steel framework underneath didn’t exist.
The politically unthinkable theory
Controlled demolition is so politically unthinkable that the media not only demeans the messenger but also ridicules and “debunks” the message rather than provide investigative reporting. Curiously, it took 441 days for the president’s 9/11 Commission to start an “investigation” into a tragedy where more than 2,500 WTC lives were taken. The Commission’s investigation also didn’t include the possibility of controlled-demolition, nor did it include an investigation into the “unusual and unprecedented” manner in which WTC Building #7 collapsed.
The media has basically kept the collapse of WTC Building #7 hidden from public view. However, instead of the Twin Towers, let’s consider this building now. Building #7 was a 47-story structural steel World Trade Center Building that also collapsed onto itself at free-fall speed on 9/11. This structural steel building was not hit by a jetliner, and collapsed seven hours after the Twin Towers collapsed and five hours after the firemen had been ordered to vacate the building and a collapse safety zone had been cordoned off. Both of the landmark buildings on either side received relatively little structural damage and both continue in use today.
Contrary to the sudden collapse of the Twin Towers and Building #7, the four other smaller World Trade Center buildings #3, #4, #5, and #6, which were severely damaged and engulfed in flames on 9/11, still remained standing. There were no reports of multiple explosions. The buildings had no pools of molten metal (a byproduct of explosives) at the base of their elevator shafts. They created no huge caustic concrete/cement and asbestos dust clouds (only explosives will pulverize concrete into a fine dust cloud), and they propelled no heavy steel beams horizontally for three hundred feet or more.
The collapse of WTC building #7, which housed the offices of the CIA, the Secret Service, and the Department of Defense, among others, was omitted from the government’s 9/11 Commission Report, and its collapse has yet to be investigated.
Perhaps it is time for these and other unanswered questions surrounding 9/11 to be thoroughly investigated. Let’s start by contacting our congressional delegation.
William Rice, P.E., is a registered professional civil engineer who worked on structural steel (and concrete) buildings in Boston, New York, and Philadelphia. He was also a professor at Vermont Technical College where he taught engineering materials, structures lab, and other building related courses.
http://www.vermontguardian.com/commenta … wers.shtml
By William Rice
Posted March 1, 2007
Having worked on structural steel buildings as a civil engineer in the era when the Twin Towers were designed and constructed, I found some disturbing discrepancies and omissions concerning their collapse on 9/11.
I was particularly interested in the two PBS documentaries that explained the prevailing theories as determined by two government agencies, FEMA and NIST (National Institute of Science and Technology). The first (2002) PBS documentary, Why the Towers Fell, discussed how the floor truss connectors failed and caused a “progressive pancake collapse.”
The subsequent 2006 repackaged documentary Building on Ground Zero explained that the connectors held, but that the columns failed, which is also unlikely. Without mentioning the word “concrete,” the latter documentary compared the three-second collapse of the concrete Oklahoma City Murrah Federal Building with that of the Twin Towers that were of structural steel. The collapse of a concrete-framed building cannot be compared with that of a structural steel-framed building.
Since neither documentary addressed many of the pertinent facts, I took the time to review available material, combine it with scientific and historic facts, and submit the following two theories for consideration.
The prevailing theory
The prevailing theory for the collapse of the 110-story, award-winning Twin Towers is that when jetliners flew into the 95th and 80th floors of the North and South Towers respectively, they severed several of each building’s columns and weakened other columns with the burning of jet fuel/kerosene (and office combustibles).
However, unlike concrete buildings, structural steel buildings redistribute the stress when several columns are removed and the undamaged structural framework acts as a truss network to bridge over the missing columns.
After the 1993 car bomb explosion destroyed columns in the North Tower, John Skilling, the head structural engineer for the Twin Towers, was asked about an airplane strike. He explained that the Twin Towers were originally designed to withstand the impact of a Boeing 707 (similar in size to the Boeing 767). He went on to say that there would be a horrendous fire from the jet fuel, but “the building structure would still be there.”
The 10,000 gallons of jet fuel (half capacity) in each jetliner did cause horrendous fires over several floors, but it would not cause the steel members to melt or even lose sufficient strength to cause a collapse. This is because the short-duration jet fuel fires and office combustible fires cannot create (or transmit to the steel) temperatures hot enough. If a structural steel building could collapse because of fire, it would do so slowly as the various steel members gradually relinquished their structural strength. However, in the 100-year history of structural-steel framed buildings, there is no evidence of any structural steel framed building having collapsed because of fire.
Let’s assume the unlikelihood that these fires could weaken all of the columns to the same degree of heat intensity and thus remove their structural strength equally over the entire floor, or floors, in order to cause the top 30-floor building segment (South Tower WTC #2) to drop vertically and evenly onto the supporting 79th floor. The 30 floors from above would then combine with the 79th floor and fall onto the next level down (78th floor) crushing its columns evenly and so on down into the seven levels below the street level.
The interesting fact is that each of these 110-story Twin Towers fell upon itself in about ten seconds at nearly free-fall speed. This violates Newton’s Law of Conservation of Momentum that would require that as the stationary inertia of each floor is overcome by being hit, the mass (weight) increases and the free-fall speed decreases.
Even if Newton’s Law is ignored, the prevailing theory would have us believe that each of the Twin Towers inexplicably collapsed upon itself crushing all 287 massive columns on each floor while maintaining a free-fall speed as if the 100,000, or more, tons of supporting structural-steel framework underneath didn’t exist.
The politically unthinkable theory
Controlled demolition is so politically unthinkable that the media not only demeans the messenger but also ridicules and “debunks” the message rather than provide investigative reporting. Curiously, it took 441 days for the president’s 9/11 Commission to start an “investigation” into a tragedy where more than 2,500 WTC lives were taken. The Commission’s investigation also didn’t include the possibility of controlled-demolition, nor did it include an investigation into the “unusual and unprecedented” manner in which WTC Building #7 collapsed.
The media has basically kept the collapse of WTC Building #7 hidden from public view. However, instead of the Twin Towers, let’s consider this building now. Building #7 was a 47-story structural steel World Trade Center Building that also collapsed onto itself at free-fall speed on 9/11. This structural steel building was not hit by a jetliner, and collapsed seven hours after the Twin Towers collapsed and five hours after the firemen had been ordered to vacate the building and a collapse safety zone had been cordoned off. Both of the landmark buildings on either side received relatively little structural damage and both continue in use today.
Contrary to the sudden collapse of the Twin Towers and Building #7, the four other smaller World Trade Center buildings #3, #4, #5, and #6, which were severely damaged and engulfed in flames on 9/11, still remained standing. There were no reports of multiple explosions. The buildings had no pools of molten metal (a byproduct of explosives) at the base of their elevator shafts. They created no huge caustic concrete/cement and asbestos dust clouds (only explosives will pulverize concrete into a fine dust cloud), and they propelled no heavy steel beams horizontally for three hundred feet or more.
The collapse of WTC building #7, which housed the offices of the CIA, the Secret Service, and the Department of Defense, among others, was omitted from the government’s 9/11 Commission Report, and its collapse has yet to be investigated.
Perhaps it is time for these and other unanswered questions surrounding 9/11 to be thoroughly investigated. Let’s start by contacting our congressional delegation.
William Rice, P.E., is a registered professional civil engineer who worked on structural steel (and concrete) buildings in Boston, New York, and Philadelphia. He was also a professor at Vermont Technical College where he taught engineering materials, structures lab, and other building related courses.
http://www.vermontguardian.com/commenta … wers.shtml
The lateral support remained intact because the distibution around the perimeter was still adequate while the core in the center continued to burn. It wasn't until you placed inertia (When it started to fall) into the equation that you start to see the effects of the lateral damage. You know nothing about me and you challenge my intelligence. Spend more time reading, less time with assumptions, and join the rest of us on the rational side.TigerXtrm wrote:
Yea that's a nice copy and paste you did there, but all I see in that lengthy piece of text is a lot of fancy terms that mean hardly anything to a normal person. I bet you don't even know what he's talking about half that article. In short he's saying that the plane destroyed the core and some support colloms but that the remaining beams divided the weight which is why it collapsed in such a nice way.Kmarion wrote:
G Charles Clifton, Structural Engineer.
If this was the case then shouldn't the entire top half of the South Tower have plunged down because it tipped over at the start of the collapse? The logic this theory follows would have made it impossible for all three structures to have come down to ground level. The collapse would have stopped 20 stories up and the debris would have scattered all over the financial district because eventually rubble would tip over to one side and drag the rest of the collapse that way, leaving whatever is underneath unharmed.
Tiger
Maybe in the mess of planes flying into the towers and two 110 story buildings collapsing that it could have been damaged?TigerXtrm wrote:
And on a completely different note, this article points the finger at destroyed beams by the plane. If that was the case for both WTC 1 and 2 to collapse, then what happened to WTC 7? I didn't see a plane destroy any beams there... nor did it have to distribute the weight because it was missing a support beam...
Last edited by Kmarion (2007-03-04 12:49:56)
Xbone Stormsurgezz
fixed.BN wrote:
http://www.whatreallyhappened.com/IMAGE … _small.jpgHunterOfSkulls wrote:
If you really want to get them going, point out how steel support beams don't have to melt in order to fail. That always pisses them off.
I am no expert.
You cant cut beams in the middle of a building without someone noticing.
Those are snapped.
Because i don't trust the structural engineers or the government to provide an honest account.RicardoBlanco wrote:
No, you're not an expert, so why not let the structural engineers decide.BN wrote:
http://www.whatreallyhappened.com/IMAGE … _small.jpgHunterOfSkulls wrote:
If you really want to get them going, point out how steel support beams don't have to melt in order to fail. That always pisses them off.
I am no expert but that looks cut to me.
There are plenty of good unanswered questions along with a lot of shite as well.
You realize this counts as noticing, right? Like, someone has noticed, and people noticed what sounded like explosions. So, ruling it out because someone 'would have noticed', doesn't work. Second, if it snapped, (which is completely plausible, there could have been a fault in the steel or some such) why is there melted steel on the end?theelviscerator wrote:
fixed.BN wrote:
http://www.whatreallyhappened.com/IMAGE … _small.jpgHunterOfSkulls wrote:
If you really want to get them going, point out how steel support beams don't have to melt in order to fail. That always pisses them off.
I am no expert.
You cant cut beams in the middle of a building without someone noticing.
Those are snapped.
I would imagine thats where they were initially welded together.jonsimon wrote:
You realize this counts as noticing, right? Like, someone has noticed, and people noticed what sounded like explosions. So, ruling it out because someone 'would have noticed', doesn't work. Second, if it snapped, (which is completely plausible, there could have been a fault in the steel or some such) why is there melted steel on the end?theelviscerator wrote:
fixed.
You cant cut beams in the middle of a building without someone noticing.
Those are snapped.
I like the advertising on the site that is hosting that photo..lol
Obviously they are marketing to the gullible.
Xbone Stormsurgezz
I prefer the "blind eye" theory to actual demolition.
I can concede it probably was the planes that brought down the twin towers; however the government investigations were so badly run as to have easily allowed a cover-up, and the evidence for the conclusions is badly presented and lacking depth at best (on both sides).
I'm the first to point out when a theory doesn't stand up what-so-ever, but I'd rather see open and impartial investigations based on evidence gathered by truly independent parties, rather than the published self-authored narratives which seem to be the fashion these days. The current system doesn't even allow the possibility of investigation of government agency involvement.
I can concede it probably was the planes that brought down the twin towers; however the government investigations were so badly run as to have easily allowed a cover-up, and the evidence for the conclusions is badly presented and lacking depth at best (on both sides).
I'm the first to point out when a theory doesn't stand up what-so-ever, but I'd rather see open and impartial investigations based on evidence gathered by truly independent parties, rather than the published self-authored narratives which seem to be the fashion these days. The current system doesn't even allow the possibility of investigation of government agency involvement.
UON there were absolutely people trying to cover shit up. But I think it has more to do with incompetence and complete failures.
Xbone Stormsurgezz
Since fucking when are H-beams welded together like that, with the end cut off at an angle. I don't work in the building industry but even I know that method would be the most stupid and unsollid construction ever. If you really think that when a steel beam is snapped in half it leaves a smooth cut like that, maybe its not the conspiracy theorists that are the nutters. That beam was cut, there is no denying that.Kmarion wrote:
I would imagine thats where they were initially welded together.jonsimon wrote:
You realize this counts as noticing, right? Like, someone has noticed, and people noticed what sounded like explosions. So, ruling it out because someone 'would have noticed', doesn't work. Second, if it snapped, (which is completely plausible, there could have been a fault in the steel or some such) why is there melted steel on the end?theelviscerator wrote:
fixed.
You cant cut beams in the middle of a building without someone noticing.
Those are snapped.
I like the advertising on the site that is hosting that photo..lol
Obviously they are marketing to the gullible.
http://i2.tinypic.com/2q313lw.png
BUT, the play devils advocate: They might have had to cut some beams for cleaning the mess and transport. Though that would not explain why they are cut in this manner.
You are correct. I mean, you are not an expert. you are looking at debris either standing at ground level or the lower stories, then yelling "look! no plane marks!" About 90 floors up, burning fuel spread across several floors, massively incresing the temperature in the area. As the temp increases, the steel weakens. It is not a binary solution. Steel isn't either A) strong, or B) melted. As a metal increases, it becomes more maleable. Look at how blacksmiths work sometime. They take a chuck of metal, heat it up, and bend it into what they want. They don't have to melt it. All that had to happen was for the steel supports to lose 10 - 20% of its strength. Then they no longer have the strength to support the weight above them. As that debris falls, it makes it to floors that were unaffected by the flames, but by then there was too much weight falling for the event to be stopped, and the collapsed continued.BN wrote:
http://www.whatreallyhappened.com/IMAGE … _small.jpgHunterOfSkulls wrote:
If you really want to get them going, point out how steel support beams don't have to melt in order to fail. That always pisses them off.
I am no expert but that looks cut to me.
There are plenty of good unanswered questions along with a lot of shite as well.
Point is, the failing steel from the fuel fire will have different characteristics from the steel that failed due to excessive load. How hard is that for people to comprehend?
You conspiracy theorist, you.Kmarion wrote:
UON there were absolutely people trying to cover shit up. But I think it has more to do with incompetence and complete failures.
I agree with that completely. I don’t think it was a government staged attack.Kmarion wrote:
UON there were absolutely people trying to cover shit up. But I think it has more to do with incompetence and complete failures.
But I do think it was gross incompetence on behalf of the government
sorry, but i know a little bit about welding/metal working and etcTigerXtrm wrote:
Since fucking when are H-beams welded together like that, with the end cut off at an angle. I don't work in the building industry but even I know that method would be the most stupid and unsollid construction ever. If you really think that when a steel beam is snapped in half it leaves a smooth cut like that, maybe its not the conspiracy theorists that are the nutters. That beam was cut, there is no denying that.Kmarion wrote:
I would imagine thats where they were initially welded together.jonsimon wrote:
You realize this counts as noticing, right? Like, someone has noticed, and people noticed what sounded like explosions. So, ruling it out because someone 'would have noticed', doesn't work. Second, if it snapped, (which is completely plausible, there could have been a fault in the steel or some such) why is there melted steel on the end?
I like the advertising on the site that is hosting that photo..lol
Obviously they are marketing to the gullible.
http://i2.tinypic.com/2q313lw.png
BUT, the play devils advocate: They might have had to cut some beams for cleaning the mess and transport. Though that would not explain why they are cut in this manner.
i assume you are talking about this image... How can you say those are cut? If they were cut, they would have to ahve been cut by a plasma cutter, which i know for a fact is not something you can carry around very easily. The smallest plasma cutters weigh between 40 and 80 pounds for the unit alone, and of course you'd have to carry the gas (argon most likely) in a tank too. You will not be able to bring one of those into a building without alerting anyone who might actually care. It just won't happen. Those beams look exactly like what happens when a weld snaps... And unless you can prove to me that you really know anything about welding or metal working you should shut up.
a quick welding lesson btw... You take two pieces of metal, signified by \ and /, and weld them to make \/
you heat up the structure until it is near melting point. Now say the welding metal has a higher melting point than the steel. Suddenly as the steel bends slightly, the weld comes under extreme strees, far greater than it was made to endure. The weld snaps. You have two pieces of metal now, signified by \ and /. Look familiar? The snap would be along a weld line, and it would be pretty straight except for the chunks of weld material on either beam
Lololololololol...LawJik wrote:
The pancake theory ia a joke.. you people havent even mentioned the word "pancake" , none of you have studied this topic, dont base your debating on things you heard in passing by on Fox News.
The World Trade Towers, were demolished by using Thermate, it is a known, discovered, fact.
As usmarine said, your whole premise is "don't trust fox news, trust this cheap internet video!" It is a known, discovered fact that you are completely delusional.
Because metal or steel doesn't just 'snap' like a piece of chocolat, leaving two clear cut sides. If steel would 'snap' under high pressure or heat, it wouldn't snap before first twisting and turning into every possible direction before it decides to give in to the weight. The result would be a twisted and turned piece of steel completely deformed from what it used to be. What I see in the picture is a clean cut, untwisted, piece of steel.Blehm98 wrote:
sorry, but i know a little bit about welding/metal working and etcTigerXtrm wrote:
Since fucking when are H-beams welded together like that, with the end cut off at an angle. I don't work in the building industry but even I know that method would be the most stupid and unsollid construction ever. If you really think that when a steel beam is snapped in half it leaves a smooth cut like that, maybe its not the conspiracy theorists that are the nutters. That beam was cut, there is no denying that.Kmarion wrote:
I would imagine thats where they were initially welded together.
I like the advertising on the site that is hosting that photo..lol
Obviously they are marketing to the gullible.
http://i2.tinypic.com/2q313lw.png
BUT, the play devils advocate: They might have had to cut some beams for cleaning the mess and transport. Though that would not explain why they are cut in this manner.
i assume you are talking about this image... How can you say those are cut? If they were cut, they would have to ahve been cut by a plasma cutter, which i know for a fact is not something you can carry around very easily. The smallest plasma cutters weigh between 40 and 80 pounds for the unit alone, and of course you'd have to carry the gas (argon most likely) in a tank too. You will not be able to bring one of those into a building without alerting anyone who might actually care. It just won't happen. Those beams look exactly like what happens when a weld snaps... And unless you can prove to me that you really know anything about welding or metal working you should shut up.
a quick welding lesson btw... You take two pieces of metal, signified by \ and /, and weld them to make \/
you heat up the structure until it is near melting point. Now say the welding metal has a higher melting point than the steel. Suddenly as the steel bends slightly, the weld comes under extreme strees, far greater than it was made to endure. The weld snaps. You have two pieces of metal now, signified by \ and /. Look familiar? The snap would be along a weld line, and it would be pretty straight except for the chunks of weld material on either beam
No I do not know a whole lot about welding but I know how steel and metal acts when heated or bend. And I believe I know enough to know that a simple snap is just not possible. I'm also quite confident that not a single contractor would be stupid enough to weld two beams together in that particular manner because that would never ever sustain a 110 story building. Think about it... why would you reinforce a building by welding the support collums in a manner where they could easily slide off each other (your briliant \\ example). Wouldn't it be more logical to weld them straight on top of each other (like so: = ) so they don't lose their integrity? You only weld in an angle if you want the building to collapse... which is why they plasma cut the beams at an angle when bringing down a building in a controlled demolition. And look at that, the circle is complete.
Tiger
Last edited by TigerXtrm (2007-03-04 16:32:05)
Would thermite cut that and leave the molten metal there?Blehm98 wrote:
i assume you are talking about this image... How can you say those are cut? If they were cut, they would have to ahve been cut by a plasma cutter, which i know for a fact is not something you can carry around very easily. The smallest plasma cutters weigh between 40 and 80 pounds for the unit alone, and of course you'd have to carry the gas (argon most likely) in a tank too. You will not be able to bring one of those into a building without alerting anyone who might actually care. It just won't happen. Those beams look exactly like what happens when a weld snaps... And unless you can prove to me that you really know anything about welding or metal working you should shut up.
a quick welding lesson btw... You take two pieces of metal, signified by \ and /, and weld them to make \/
you heat up the structure until it is near melting point. Now say the welding metal has a higher melting point than the steel. Suddenly as the steel bends slightly, the weld comes under extreme strees, far greater than it was made to endure. The weld snaps. You have two pieces of metal now, signified by \ and /. Look familiar? The snap would be along a weld line, and it would be pretty straight except for the chunks of weld material on either beam
The current official version compared with the time lines of the collapses defies basically the laws of the conservation of linear/angular momentum and conservation of energy.
Conservation of momentum: Conservation of momentum is a fundamental law of physics which states that the momentum of a closed system is constant if there are no external forces acting on the system.
Or to explain it a more specific: When two objects, A and B, collide. A will exert a force on B, which will change B's momentum according to Newton's 2nd law. Similarly, B will exert a force on A, which will change A's momentum. These forces, by Newton's 3rd law, are equal and opposite, and therefore the changes in A's and B's momentum are equal and opposite.
Conservation of energy: The law of conservation of energy states that energy can neither be created from nothing nor destroyed to nothing, it only can be converted into other forms of energy. Therefore the sum of all the energies in a closed system is a constant.
How would the collapses have looked like, if we apply these two fundamental laws? The collapse would have been decelerating because part of the kinetic energy from the collapsing upper floors would have to be used to deform the lower floors (crushing and pulverizing them) giving us an inelastic collision. In reality we know that the collapse actually slightly accelerated and the total collapse ended in less then 14-16 seconds, which is near free fall speed in given environment, therefore impossible without use of external force/energy according to these laws.
Now lets take a closer look at the south tower collapse as it shows not only a linear momentum, but initially also an angular:
Initially the block consisting of the approximate 30 top floors of the tower acted as a solid object, and rotated about a fulcrum near the impact zone. Although the fulcrum was the axis of rotation, the block had two types of momentum: the angular momentum of the block around its center of gravity, and the linear momentum of its center of gravity tilting away from the tower's vertical axis. When the portion of the building below the collapse zone disintegrated, the block would preserve its angular momentum by continuing to rotate at the same rate (but the acceleration of the rotation would cease due to the removal of the torque that was being applied by intact columns at the fulcrum). But in reality, the rotation of the block rapidly decelerated as the downward plunge began.
So to summarize: The current official theory of a gravity driven progressive collapse compared to the time line holds scientifically no ground.
Please note that my emphasis is on current official theory.
Conservation of momentum: Conservation of momentum is a fundamental law of physics which states that the momentum of a closed system is constant if there are no external forces acting on the system.
Or to explain it a more specific: When two objects, A and B, collide. A will exert a force on B, which will change B's momentum according to Newton's 2nd law. Similarly, B will exert a force on A, which will change A's momentum. These forces, by Newton's 3rd law, are equal and opposite, and therefore the changes in A's and B's momentum are equal and opposite.
Conservation of energy: The law of conservation of energy states that energy can neither be created from nothing nor destroyed to nothing, it only can be converted into other forms of energy. Therefore the sum of all the energies in a closed system is a constant.
How would the collapses have looked like, if we apply these two fundamental laws? The collapse would have been decelerating because part of the kinetic energy from the collapsing upper floors would have to be used to deform the lower floors (crushing and pulverizing them) giving us an inelastic collision. In reality we know that the collapse actually slightly accelerated and the total collapse ended in less then 14-16 seconds, which is near free fall speed in given environment, therefore impossible without use of external force/energy according to these laws.
Now lets take a closer look at the south tower collapse as it shows not only a linear momentum, but initially also an angular:
Initially the block consisting of the approximate 30 top floors of the tower acted as a solid object, and rotated about a fulcrum near the impact zone. Although the fulcrum was the axis of rotation, the block had two types of momentum: the angular momentum of the block around its center of gravity, and the linear momentum of its center of gravity tilting away from the tower's vertical axis. When the portion of the building below the collapse zone disintegrated, the block would preserve its angular momentum by continuing to rotate at the same rate (but the acceleration of the rotation would cease due to the removal of the torque that was being applied by intact columns at the fulcrum). But in reality, the rotation of the block rapidly decelerated as the downward plunge began.
So to summarize: The current official theory of a gravity driven progressive collapse compared to the time line holds scientifically no ground.
Please note that my emphasis is on current official theory.