Angurse:To clarify, yes it was fast as gravity is fast, but no it wasn't "ridiculously fast."
You don't think 40 seconds for that much material to move isn't fast? If we dropped something from the top of the tower, free fall to the ground, say a tennis ball, got any idea how long that would take?
Angurse:And steel framed buildings have collapsed due to fire before.
That's news to me.
Angurse:So its just not evidence of any conspiracy.
Please don't strawman me.
Angurse:My Mistake, I've corrected my previous post.
Can you just post the #s? I'm not into this like you guys are. I'm not going to waste my day pouring through documents to debate the math or principles of physics involved. I just wanted a general idea on how long WTC 7 took to fall. I promise not to solve the 9/11 conspiracy theories (one way or another) if you tell me.
liberty student:You don't think 40 seconds for that much material to move isn't fast? If we dropped something from the top of the tower, free fall to the ground, say a tennis ball, got any idea how long that would take?
Galileo proposed that a falling body would fall with a uniform acceleration, as long as the resistance of the medium through which it was falling remained negligible, or in the limiting case of its falling through a vacuum.[84]
Where there is no property there is no justice; a proposition as certain as any demonstration in Euclid
Fools! not to see that what they madly desire would be a calamity to them as no hands but their own could bring
nirgrahamUK:Galileo proposed that a falling body would fall with a uniform acceleration, as long as the resistance of the medium through which it was falling remained negligible, or in the limiting case of its falling through a vacuum.[84]
You do this because you hate me right?
liberty student:You do this because you hate me right?
the opposite
OT, when I was in school, I had a choice of taking my exams in 2 of 3 sciences. Biology, Chemistry and Physics. I didn't have to study all 3, but I did, thinking whichever I had the highest aptitude in, would naturally be my choices for examination.
The problem is, I fell in love with biology and chemistry, and never gave physics a chance. I think it was because my physics instructor was the spitting image of Leonard Nimoy, and it is intimidating to be taught science by a Starfleet Science Officer, particularly one as distinguished as Mr. Spock.
Now, back to reality conspiracy.
He is basically saying that a body will fall at the same speed unless you have a giant wind fan under him that exerts upward pressure or a giant wind fan above him which would exert downward pressure or vice versa.
'Men do not change, they unmask themselves' - Germaine de Stael
liberty student asked: " If we dropped something from the top of the tower, free fall to the ground, say a tennis ball, got any idea how long that would take?"
If you use a billiard ball as an example instead- I can answer your question :
"From the rooftop of WTC1, drop one billiard ball over the edge. As it falls, it accelerates. If it were in a vacuum, it would hit the pavement, 1368 feet below, in 9.22 seconds, shown by the blue curve in the figure, below. It will take longer if air resistance is considered, but for simplicity, we'll neglect air resistance. This means that the calculated collapse times are more generous to the official story than they need to be. "
Source of above quote and pic below here.
For more information about onebornfree, please see profile.[ i.e. click on forum name "onebornfree"].
Laughing Man: He is basically saying that a body will fall at the same speed unless you have a giant wind fan under him that exerts upward pressure or a giant wind fan above him which would exert downward pressure or vice versa.
Right I understand that, but my question is, how many seconds is that?
Like I said, I'm not here to debate physics, I just want to know why there is so much hair splitting over the collapse of the building. If it takes 50% longer than a controlled demolition, say from 15 seconds to 23 seconds, does that rule out foul play? I don't think so. There is no reason to believe demolition could not be staggered.
But if we had examples of buildings that big actually falling under other circumstances, then maybe we could add some context to the 40 second (debatable apparently) time to fall. If it took other buildings 15 minutes, then 40 seconds looks a lot less natural than when comparing it to 15 seconds for a CD. But if the building normally collapse in say, an equivalent 45 seconds, then 40 seconds (to me at least) looks a lot less like foul play.
I don't think any conspiracies are going to be exposed by debunking strawmen or scientific arguments. I think that is precisely the sort of time wasting the government wants everyone to do, instead of asking for FOIA releases on classified testimony and such, which could lend a lot more insight and context into what happened with regards to readiness, and reaction.
Has anyone besides me brought up Neils Harrit's paper? Have the debunkers seen any debunking challenges to it?
The kinetic energy of the top part of the tower impacting the
floor below was found to be about 8.4 larger than the plastic
energy absorption capability of the underlying story, and considerably
higher than that if fracturing were taken into account
Bažant and Zhou 2002a. This fact, along with the fact that
during the progressive collapse of underlying stories Figs. 1d
and 2 the loss of gravitational potential per story is much greater
than the energy dissipated per story, was sufficient for Bažant and
Zhou 2002a to conclude, purely on energy grounds, that the
tower was doomed once the top part of the tower dropped through
the height of one story or even 0.5 m. It was also observed that
this conclusion made any calculations of the dynamics of progressive
collapse after the first single-story drop of upper part superfluous.
The relative smallness of energy absorption capability
compared to the kinetic energy also sufficed to explain, without
any further calculations, why the collapse duration could not have
been much longer say, twice as long or more than the duration
of a free fall from the tower top.
Therefore, no further analysis has been necessary to prove that
the WTC towers had to fall the way they did, due to gravity alone.
However, a theory describing the progressive collapse dynamics
beyond the initial trigger, with the WTC as a paradigm, could
nevertheless be very useful for other purposes, especially for
learning from demolitions. It could also help to clear up misunderstanding
and thus to dispel the myth of planted explosives.
Its formulation is the main objective of what follows.
http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/466.pdf
twistedbydsign99: http://www.911myths.com/WTCREPORT.pdf bottom of page 2, 11.3 +- 1.5 seconds and 1-2 seconds for upper block. That range works out to [~11 to 15]. He is a 911 conspiracy debunker btw not a truther.
http://www.911myths.com/WTCREPORT.pdf
bottom of page 2, 11.3 +- 1.5 seconds and 1-2 seconds for upper block. That range works out to [~11 to 15]. He is a 911 conspiracy debunker btw not a truther.
He uses seismic activity to measure the core just as NIST, however the NIST says that there aren't any reliable indicators after the core. But its a moot point as both show the core falling within the natural range.
LS:I just want to know why there is so much hair splitting over the collapse of the building. If it takes 50% longer than a controlled demolition, say from 15 seconds to 23 seconds, does that rule out foul play? I don't think so. There is no reason to believe demolition could not be staggered.
February 17 - 1600 - Giordano Bruno is burnt alive by the catholic church. Aquinas : "much more reason is there for heretics, as soon as they are convicted of heresy, to be not only excommunicated but even put to death."
i dont see its credible. it first states
In stage 1 (Fig. 1), the conflagration caused by the aircraft fuel spilled into the structure causes the steel of the columns to be exposed to sustained temperatures apparently exceeding 800°C
and then goes onto criticize it
but if you actually look at the paper the only reference to the number '800' contained in the thing is this :
Because a significant amount of steel insulation was stripped,
many structural steel members heated up to 600°C, as confirmed
by annealing studies of steel debris NIST 2005 the
structural steel used loses about 20% of its yield strength
already at 300°C, and about 85% at 600°C NIST 2005;
and exhibits significant viscoplasticity, or creep, above
450°C e.g., Cottrell 1964, p. 299, especially in the columns
overstressed due to load redistribution; the press reports right
after September 11, 2001 indicating temperature in excess of
800°C, turned out to be groundless, but Bažant and Zhou’s
analysis did not depend on that.
liberty student: You don't think 40 seconds for that much material to move isn't fast? If we dropped something from the top of the tower, free fall to the ground, say a tennis ball, got any idea how long that would take?
Not "ridiculously fast," no. The amount of material isn't really important.
liberty student:That's news to me.
The McCormick Center in Chicago, and the Sight and Sound Theater in Pennsylvania collapsed due to fire.
liberty student:Please don't strawman me.
My apologies, I'm just trying to keep it related.
liberty student: Can you just post the #s? I'm not into this like you guys are. I'm not going to waste my day pouring through documents to debate the math or principles of physics involved. I just wanted a general idea on how long WTC 7 took to fall. I promise not to solve the 9/11 conspiracy theories (one way or another) if you tell me.
It was fast, but not "ridiculously fast." (I'll post in more detail later.)
liberty student: Like I said, I'm not here to debate physics, I just want to know why there is so much hair splitting over the collapse of the building. If it takes 50% longer than a controlled demolition, say from 15 seconds to 23 seconds, does that rule out foul play? I don't think so. There is no reason to believe demolition could not be staggered.
It doesn't rule out foul play at all, it rules it out as proof of foul play. Many "truthers" use it as evidence when it simply isn't.
i dont see its credible. it first states In stage 1 (Fig. 1), the conflagration caused by the aircraft fuel spilled into the structure causes the steel of the columns to be exposed to sustained temperatures apparently exceeding 800°C and then goes onto criticize it
i see its actually a 'critique' of a different paper by Bazant. and Bazant did not 'require' 800'c temperature for his explanation....
this:
The power and fury of a typical house fire is immensely underestimated by the average person. The National Fire Protection Association has conducted accurate tests involving the growth and temperatures of fires. Did you know that just 3 minutes and 3 seconds after the start of an average living room fire involving a couch, that the temperature 3 feet above the floor within the room is over 500 F? Just 38 seconds later, the temperature in the room is 1,400 F. If you want to protect your possessions from an inferno like this, you will need more than a simple metal box.
http://www.askthebuilder.com/201_Fire_and_Burglar_Safes_-_A_Hot_Item_.shtml
In only 3 1/2 minutes, the heat from a house fire can reach over 1100 degrees Fahrenheit.
http://www.redcross-cmd.org/chapter/firefactsmd.html
and this:
the structural steel used loses about 20% of its yield strength already at 300°C, and about 85% at 600°C NIST 2005;and exhibits significant viscoplasticity, or creep, above450°C e.g.
-Bazant.
-------------------------------------------------------------------
1100F' ~ 600'C
sorry
liberty student:Can we get agreement that 40 seconds is still ridiculously fast for a building that size to fall, let alone for it to happen to two buildings, damaged in two discrete ways, on the same day?
No, not once your understand the design of the buildings, the fact that both buildings were hit by a 200 ton 767 traveling at 500 MPH and the physical forces involved, especially the mass of the portions of the building above the structural failure point.
liberty student:Does anyone have any data on how fast WTC 7 came down?
Visible collapse is about 13.5 seconds, actual collapse is more like 18 seconds.
"Anarchism misunderstands the real nature of man. It would be practicable only in a world of angels and saints" - Ludwig von Mises
twistedbydsign99: 1. the top of the south tower was already falling over 2. the path of most resistence was straight down it was the least likely path.
1. the top of the south tower was already falling over
2. the path of most resistence was straight down it was the least likely path.
The top of the south tower was still connected to the rest of the building, it is not a separate "cardboard box". Why would the likely path not be in the direction of gravity?
So where are we?Looks like a lot of heated discussion about collapse times,tennis balls and related physics.Well, as I originally point out on page 5 of this thread and reproduce again below, using calculations involving basic laws of physics, a billiard ball dropped from the top of WTC1 [1368 feet ] , and in free fall for the entire length of its journey down, would have hit the pavement below 9.22 seconds later, in a vacuum, that is, without air resistance slowing its path.Dr Reynolds of course is also fully aware of this same fact.So to sum up the story so far here, if we assume, for the sake of argument, that the collapse videos are real and depict actual events as they happened in real time, we appear to have a general consensus of collapse times for both towers, top to bottom - and being generous here- of anywhere between between 10 and 20 seconds [straight down- start to finish] for those 2, 1300 ft. plus, 500,000 ton steel and concrete buildings whose parts would encounter air resistance as they fell, plus direct resistance from each floor below as it/they collided and gave way, versus the time of 9.22 seconds for one single [8 oz.? ] free-falling billiard ball in a vacuum, to travel the same distance, yes?Quote:
"From the rooftop of WTC1, drop one billiard ball over the edge. As it falls, it accelerates. If it were in a vacuum, it would hit the pavement, 1368 feet below, in 9.22 seconds, shown by the blue curve in the figure, below. It will take longer if air resistance is considered, but for simplicity, we'll neglect air resistance. This means that the calculated collapse times are more generous to the official story than they need to be. " Quote source
Onebornfree - regarding the last bit you posted, the weight of an object doesn't affect how fast it falls. Shape (and thus wind resistance) does - but it's disingenuous to ask "how could 500k tons of stuff fall nearly as fast as something that weighs 8 oz".
And I think I missed it, but if there were no planes then what happened? Controlled demolitions? It seems unlikely to me that such an event could be easily concealed. Hell, the Germans couldn't keep even relatively small massacres a secret and they got a far greater percent of the population on board. How were so many Americans convinced to essentially commit treason but also keep it a secret?
Ska is lame and so am I.
Of course weight matters for acceleration.
If you ignore air resistance than it doesn't, really - it will be the same for both object. So the billiard ball and the top floor would fall at the same rate. Putting air resistance back in certainly makes things more interesting (and I don't have the math or physics to say how it would affect a billiard ball in comparison to a floor on top of another floor falling upon each other).
However, how can the government get away with such a large cover-up? They're not exactly known for efficiency...
And even if we've all been lied to, there were no planes, etc - does it matter? The state is evil even if it is not deceiving its people to encourage specific political conditions into developing. Exposing such a massive intrigue would certainly discredit large swathes of the government, both those responsible directly and those only involved on an ancillary level, but it would not by itself make many question the existence of government itself.
Skanarchist "Onebornfree - regarding the last bit you posted, the weight of an object doesn't affect how fast it falls. Shape (and thus wind resistance) does - but it's disingenuous to ask "how could 500k tons of stuff fall nearly as fast as something that weighs 8 oz".
Point taken- yes, a 50 ton steel girder or whatever would fall/accellerate at exactly the same speed as an 8oz billiard ball in a vacuum and reach the ground at exactly the same time - size and weight would not matter at all.
However, in air, a large steel girder dropped from the top of the WTC and falling unimpeded next to a billiard ball released at the exact same moment would [reasonably?] , because of the enormous size difference [ ie greater air resistance] be assumed to be slowed more than the billiard ball when moving through that air, but much more importantly, during a complete building collapse scenario, [as opposed to an unimpeded fall through air] the girder would also be considerably slowed by impediment /resistance of the building directly in its path beneath it -unless of course that structure below the falling girder has already collapsed /been removed somehow ahead of what is coming down from above.
Yes/ no?
Skanarchist : "And even if we've all been lied to, there were no planes, etc - does it matter? The state is evil even if it is not deceiving its people to encourage specific political conditions into developing. Exposing such a massive intrigue would certainly discredit large swathes of the government, both those responsible directly and those only involved on an ancillary level, but it would not by itself make many question the existence of government itself."
"Does it matter?"
To whom? would be my question.
I don't know about waking everybody, or even anybody up, I have no interest in movements to change the world.
If you were to become convinced in your own mind that you/we were lied to , what you have to consider, it seems to me, are the implications for yourself and your freedom - no-one else.
Media Complicity
If what I and other demented souls claim is true, then obviously "the rabbit hole" is a (w)hole lot deeper than you currently assume, because obviously [or it should be] it points to a massive media involvement and complicity in the telling of the governments lie(s).
scineram:Of course weight matters for acceleration.
No. It doesn't. Refer to your 9th grade physical science textbook. The acceleration due to gravity is 32 feet per second squared. Weight doesn't enter into it.
My favorite 911 nutjob comment came from ex governor Jesse Venture who said "There is no way that building could have fallen at the speed of gravity".
Poptech: Visible collapse is about 13.5 seconds, actual collapse is more like 18 seconds.
Then why does the official NIST report find that the collapse was only 5.4 seconds? Even that number is subject to debate - as many have shown the time to be closer to 3.9 - 4.2. Even after watching an unaltered video of the collapse, I can not believe anyone would argue that the event lasted longer than 5 to 6 seconds.
DBratton: My favorite 911 nutjob comment came from ex governor Jesse Venture who said "There is no way that building could have fallen at the speed of gravity".
This is the main reason I don't follow amateur investigations, which happen to be the main source of conspiracy theories. Although, I did like 'fabled enemies' investigation - even if some things weren't exactly correct.
onebornfreedotblogspotdotcom:~snip~ Yes/ no?
With my extremely limited understanding of that kind of problem I would say yes but that doesn't really mean anything. I still have a hard time that such a project could be engineered in absolute secrecy and have remained secret for so long. For it would mean that everyone was onboard at the time and has still felt neither remorse nor realized how famous they would become for breaking their silence in the current political climate.
onebornfreedotblogspotdotcom:"Does it matter?" To whom? would be my question. I don't know about waking everybody, or even anybody up, I have no interest in movements to change the world. If you were to become convinced in your own mind that you/we were lied to , what you have to consider, it seems to me, are the implications for yourself and your freedom - no-one else. Media Complicity If what I and other demented souls claim is true, then obviously "the rabbit hole" is a (w)hole lot deeper than you currently assume, because obviously [or it should be] it points to a massive media involvement and complicity in the telling of the governments lie(s).
The only thing I could think if this were true is that the government is far more competent than they've let on previously. Which would only affect my freedom from a practical standpoint - that they are perhaps better at squelching individual freedom. It doesn't change how morally wrong the state is.
onebornfreedotblogspotdotcom:"From the rooftop of WTC1, drop one billiard ball over the edge. As it falls, it accelerates. If it were in a vacuum, it would hit the pavement, 1368 feet below, in 9.22 seconds, shown by the blue curve in the figure, below. It will take longer if air resistance is considered, but for simplicity, we'll neglect air resistance. This means that the calculated collapse times are more generous to the official story than they need to be. "
We already went over this and it is covered in the NIST report.
NIST Investigation of the World Trade Center Disaster FAQs - Supplement (August 30, 2006) (National Institute of Standards and Technology)
NIST:6. How could the WTC towers collapse in only 11 seconds (WTC 1) and 9 seconds (WTC 2)—speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)? NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A). [...] From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse.
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A). [...]
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse.
North Tower Core Still Standing
JackSkylark:Then why does the official NIST report find that the collapse was only 5.4 seconds?
NIST was referring to a video of 18 stories (not the whole building, 47 stories) used by Truthers to make "free-fall" claims.
47 stories / 18 stories = 2.6 * 5.4 seconds = 14 seconds
Questions and Answers about the NIST WTC 7 Investigation (National Institute of Standards and Technology)
JackSkylark:In the draft WTC 7 report (released Aug. 21, 2008; available at http://wtc.nist.gov/media/NIST_NCSTAR_1A_for_public_comment.pdf), NIST stated that the north face of the building descended 18 stories (the portion of the collapse visible in the video) in 5.4 seconds, based on video analysis of the building collapse. This time period is 40 percent longer than the 3.9 seconds this process would have taken if the north face of the building had descended solely under free fall conditions. During the public comment period on the draft report, NIST was asked to confirm this time difference and define the reasons for it in greater detail. To further clarify the descent of the north face, NIST recorded the downward displacement of a point near the center of the roofline from first movement until the north face was no longer visible in the video.
To further clarify the descent of the north face, NIST recorded the downward displacement of a point near the center of the roofline from first movement until the north face was no longer visible in the video.
Not when it hit the ground.
You are right, I was just commenting off what I remember. Although, I think your math is off, since it discounts any more acceleration after the WTC is no longer visible - but that isn't much of a point from me.
I know this is a little off topic, but I'm curious as to what to what you make of non WTC centric conspiracy theories. Such as the relationship between the Bin Ladin family to the US government - both as a contractor and as an asset against the Soviets. Or, even more off topic, what about Israeli spying and supposed knowledge of an attack? Pakistani involvement?
Angurse:He uses seismic activity to measure the core just as NIST, however the NIST says that there aren't any reliable indicators after the core. But its a moot point as both show the core falling within the natural range.
If the range of collapse time was 11 to 15 seconds then there is cause to believe it was demolished. It is close enough to free fall speed for me to justify a new investigation, not to conclude they were demolished. However if you are saying that the collapse took 40 seconds, do you have video evidence to support this? All the collapses I've watched, timed from the beginning of motion, have not taken 40 seconds. Perhaps I have been watching propoganda, can you point me to the 40 second collapse video?
twistedbydsign99:If the range of collapse time was 11 to 15 seconds then there is cause to believe it was demolished. It is close enough to free fall speed for me to justify a new investigation, not to conclude they were demolished.
Close enough? Thats extremely vague and overlooks that fact that its very possible for it to fall so quickly. Now if its just your opinion, thats fine, but I can't see a single reasons to be skeptical simply from that.
twistedbydsign99:However if you are saying that the collapse took 40 seconds, do you have video evidence to support this? All the collapses I've watched, timed from the beginning of motion, have not taken 40 seconds. Perhaps I have been watching propoganda, can you point me to the 40 second collapse video?
No, what I said is that the total collapse possibly took 40 seconds. The 11 seconds is the elapsed time it took for the first exterior panels to strike the ground. Data after that is inconclusive as the ground was being barraged with refuse. Clouds of dust make most video evidence make determining a precise time of the total collapse an impossibility. But the NIST has pointed out that significant portions of the cores were still standing between 15-25 seconds after the panels fell.
Angurse:Close enough? Thats extremely vague and overlooks that fact that its very possible for it to fall so quickly. Now if its just your opinion, thats fine, but I can't see a single reasons to be skeptical simply from that.
Yea its my opinion there should be another investigation. 9/11, if it was a natural collapse as you believe, mark a first in architecture history, steel building collapses from fire and doesn't topple. I know not everyone is a default skeptic; I happen to be.
Angurse:No, what I said is that the total collapse possibly took 40 seconds. The 11 seconds is the elapsed time it took for the first exterior panels to strike the ground. Data after that is inconclusive as the ground was being barraged with refuse. Clouds of dust make most video evidence make determining a precise time of the total collapse an impossibility. But the NIST has pointed out that significant portions of the cores were still standing between 15-25 seconds after the panels fell.
I will look at the videos some more and see if I can lean more towards a 25 second collapse. After all it makes me happy to be corrected so I can no longer be in error if I am so.
twistedbydsign99:Yea its my opinion there should be another investigation. 9/11, if it was a natural collapse as you believe, mark a first in architecture history, steel building collapses from fire and doesn't topple. I know not everyone is a default skeptic; I happen to be.
Fair enough. However it definitely is a "first" in architectural history but I don't find that to be a call for skepticism in-and-of-itself. I mean, how many other high-rise "tube-in-tube" towers hit by a 767 going 500 mph...etc do you have to compare? You have two that I know of and they acted very similar.
twistedbydsign99:I will look at the videos some more and see if I can lean more towards a 25 second collapse. After all it makes me happy to be corrected so I can no longer be in error if I am so.
Like I said, I don't think an exact time is possible, but there are a few videos showing it beyond 11 seconds.
twistedbydsign99:mark a first in architecture history, steel building collapses from fire and doesn't topple.
As was previously mentioned. Did those other buildings have a one of kind steel tube-frame structural design and a 200-ton Boeing 767 loaded with 24,000 gallons of jet fuel crash into them at 500 MPH, causing severe structural damage to the inner core in addition to fires that reached over 2000 degrees? Fires from jet fuel can cause structural steel to fail...
Regardless this has been debunked...