Cl1mh4224rd
Philosopher
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Things go more smoothly when you use your words properly. "Converted" != "used up" in this context.
Merged Continuation - 9/11 CT subforum General Discussion Thread
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Things go more smoothly when you use your words properly. "Converted" != "used up" in this context.
dafydd
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Lol,you lecturing us on basic physics.Priceless.Keep 'em coming.
Can you prove it was exactly free fall, as opposed to approximately free fall?
Let me refresh your memory on this part:
In Stage 2, the north face descended at gravitational acceleration, as the buckled columns provided negligible support to the upper portion of the north face.
That's from NIST's NCSTAR 1-A (bold mine). You said that "the system in the NIST theory used an extra X amount of energy, violating the law of conservation of energy" and posted an equation like this:
Y + X <> Y
The correct equation, however, is:
Y + negligible X = approx. Y
The X in the NIST theory is "negligible", see the sentence above.
Now, if you show us (with proper engineering arguments, not just incredulity) why you think that NIST is wrong on the assessment of the negligibility of that energy, and how that non-negligible energy was big enough that it should have caused the lower descent rate to be detectable in the videos, maybe you have something. So far, your posts just show your failure to understand the collapse mechanism.
It's not that strange actually.
The center of gravity doesn't accelerate faster than g. The extreme does, though.
jaydeehess
Penultimate Amazing
nice,
in the WTC7 video then has anyone taken into account the fact that the bulk of the north facade ended up draped over the rest of the building indicating that it was tilting southwards as it fell? That would skew all measurements of vertcal drop velocity and subsequent derivation of acelleration which assume a perfectly vertical drop.
jaydeehess
Penultimate Amazing
Um, did bill or anyone else ever show that the headline has any basis in fact yet?
Did any main stream media cover the event?
So far all I saw from bill is more links to 911 TM pages.
alienentity
Illuminator
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Hey there. You wanted more info about the structural failures and collapse causing a period of freefall. I've dug up as much as I can for you. Suggest you also read thru NCSTAR 1-9 Vol 1 and Vol 2, as they have a boatload of really detailed documentation which should answer any questions you might have.
ETA also check out this post from A W Smith
You may very well choose to dismiss the entire report, but from this point you cannot truthfully claim that NIST did not explain the freefall with a detailed engineering description, and unsupported by evidence.
Any such statement on your part would be false.
cheers
AE
NIST NCSTAR 1-9, WTC Investigation
pp 606 -607
'Global Collapse
• The exterior column failures were sensitive to the extent of the estimated initial structuraldamage in WTC 7 due to debris impact from the collapse of WTC 1.
o For the debris impact damage scenario, the exterior column buckling began at thesouthwest corner Column 14, adjacent to the WTC 1 debris impact zone, between Floors10 and 12. The exterior columns adjacent to the (seven) columns severed in the Southwest region due to the collapse of WTC 1 were the first to buckle because additional load was distributed to them as a result of the damage. The analysis with debris impact
damage closely simulated the observed failure of the exterior façade, where the façade moved downward as a single unit.
o For the no debris impact damage scenario, the exterior columns buckled near mid-height of the building, approximately between Floors 17 and 29. If the exterior columns had buckled at mid-height, it would have been visible in the videographic records. The analysis without debris impact damage did not closely simulate the observed failure of the exterior façade.
• The observed behavior of the exterior columns during the global collapse was more closely simulated by the analysis with debris impact damage.
• As the interior columns buckled at the lower floors and the corresponding upper column sections began to move downward, the exterior columns buckled inward at the lower floors as a result of floor pull-in forces caused by the downward movement of the building core. The
floor connections to the columns had not yet failed in this region, as there were no fires observed on the west side of Floors 10 through 14 at any time during the day, so the floors were intact and able to pull the exterior columns inward.
• The south and west exterior columns buckled first, followed by the north and east face
columns.
• All exterior columns buckled between approximately Floors 7 and 14.
• Once column support was lost in the lower floors, the remaining exterior structure above began to fall vertically as a single unit.
• WTC 7 was prone to classic progressive collapse in the absence of fire-induced damage and debris impact damage when a section of Column 79 between Floors 11 and 13 was removed.
The collapse sequence demonstrated a vertical and horizontal progression of failure upon the removal of the Column 79 section, followed by downward movement at the roofline due to buckling of exterior columns, which led to the collapse of the entire building.
• The observed descent time of the upper 18 stories of the north face of WTC 7 (the floors clearly visible in the video evidence) was 40 percent greater than the computed free fall time.
A more detailed analysis of the descent of the north face found three stages: (1) a slow descent with acceleration less than that of gravity that corresponded to the buckling of the exterior columns at the lower floors, (2) a freefall descent over approximately eight stories at
gravitational acceleration for approximately 2.25 s, and (3) a decreasing acceleration as the north face encountered resistance from the structure below.
http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR 1-9 Vol 2.pdf
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CORed
Penultimate Amazing
You just demonstrated beyond any conceivable doubt that you don't understand physics.
You talk about conservation laws, but clearly you don't understand conservation of energy. GPE is not "used up" by freefall, it is converted to kinetic energy. When the freefalling object hits something that kinetic energy is still available to break stuff. Why do you think a glass table breaks when you drop a big rock on it, genius?
Now, go away, and quit talking about "conservation laws" until you get out of your mom's basement, take some classes, and actually have some idea about what you're talking about.
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TJM
Potsing Whiled Runk
Like we need more proof that truthers are MORONS:
Paid for by local troofers. According to them, Gage didn't spend a dime on it.
Gage seems to stumbled upon something I've always wanted - a self sustaining cash cow. But I couldn't live with myself if that meant pissing on the memories of the victims by taking money from the mentally ill and the hopelessly stupid though.
Paid for by local troofers. According to them, Gage didn't spend a dime on it.
Gage seems to stumbled upon something I've always wanted - a self sustaining cash cow. But I couldn't live with myself if that meant pissing on the memories of the victims by taking money from the mentally ill and the hopelessly stupid though.
TexasJack
Penultimate Amazing
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I used to live there, and if the people are anything like when I left, that crap isn't going to go over well, even with the college kids.
TJM
Potsing Whiled Runk
The more I look the more I wonder if it isn't a photoshop of somebody's pipe dream. You bought a billboard but only put up a grainy still of it on your video? Doesn't make any sense, but then I'm not a truther.
TexasJack
Penultimate Amazing
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I do know some people up there, but haven't talked to them in quite a time. Maybe I'll give them a holler. Higuera is a main street in SLO, so it shouldn't be hard to find.
Telltale Tom
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Well, so Harvard are trying to get in on it now and prove WTC 7 should have fallen faster than freefall.
jaydeehess
Penultimate Amazing
To say "WTC 7 should have fallen faster than free fall" is a misrepresentation of what pgimeno has illustrated.
It requires that the entirety of the structure known as WTC fall strictly vertcally with no rotation as it does so. pgimeno has shown that if the upper structure was rotating as it fell then the extremes would indeed be moving in the vertical direction at a different velocity than the center of mass of that upper structure.
The farther from the CoMass the extremes of the structure are, the more pronounced this effect.
It requires that the entirety of the structure known as WTC fall strictly vertcally with no rotation as it does so. pgimeno has shown that if the upper structure was rotating as it fell then the extremes would indeed be moving in the vertical direction at a different velocity than the center of mass of that upper structure.
The farther from the CoMass the extremes of the structure are, the more pronounced this effect.
A couple of clarifications.
I just intended to illustrate that falling faster than freefall is not a physical impossibility in the absence of external energy. I don't claim that that's the mechanism by which the building's corner fell faster. It's a fact that several people who have measured it using the videos, including NIST, got >1g acceleration, so it's reasonable to assume that it did.
For a discussion of what the exact mechanism could be, there's this W.D.Clinger's post:
http://www.internationalskeptics.com/forums/showthread.php?p=6111592#post6111592
(ETA: He later adds this further explanation:
http://www.internationalskeptics.com/forums/showthread.php?p=6146028#post6146028)
and a followup by tfk (which includes a similar video to the one I posted):
http://www.internationalskeptics.com/forums/showthread.php?p=6111947#post6111947
and the discussion goes on along the thread.
Finally, about Telltale Tom, take his "trutherism" with a grain of salt
(think Poe's law)
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dafydd
Banned
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A couple of clarifications.
I just intended to illustrate that falling faster than freefall is not a physical impossibility in the absence of external energy. I don't claim that that's the mechanism by which the building's corner fell faster. It's a fact that several people who have measured it using the videos, including NIST, got >1g acceleration, so it's reasonable to assume that it did.
For a discussion of what the exact mechanism could be, there's this W.D.Clinger's post:
http://www.internationalskeptics.com/forums/showthread.php?p=6111592#post6111592
(ETA: He later adds this further explanation:
http://www.internationalskeptics.com/forums/showthread.php?p=6146028#post6146028)
and a followup by tfk (which includes a similar video to the one I posted):
http://www.internationalskeptics.com/forums/showthread.php?p=6111947#post6111947
and the discussion goes on along the thread.
Finally, about Telltale Tom, take his "trutherism" with a grain of salt
A grain? A kilo would be more like it.
ElMondoHummus
0.25 short of being half-witted
I'm sorry to resurrect a week old post, but I sort of feel the need to highlight a facepalm-worthy statement by our resident truther here
Insert Picard facepalm for cmatrix's statement here: --->*<---
Gravitational potential energy does not get "used up" when a body is falling; it gets converted to kinetic energy. The act of accelerating to the ground is not a consumptive one. Do not mistake propulsion for gravitational acceleration.
Furthermore, you continually ignore the damage to the interior from the fires. Again: Columns on one side of the building were compromised by the fires, this lead to a series of floor failures ultimately leading to the buckling of many columns low in the building. And that's the reason the collapse happen to begin with: Those interior failures. The kinetic energy from the floors above those buckled columns is overcoming what little resistence is left after those columns buckle.
You continually cite the columns as if they were never 1. Part of a system that included floors and trusses, and 2. Weren't compromised by the fires and failures of the floors and trusses. You fail to understand the collapse progression, and you fail to recognize that fact. You need to study the actual events, not the truther myths about them.
No, it is what was measured. Refer to NCSTAR 1-9, table 12-2. This was measured during a study of the video.
You'd better bone up on the arguments before going anywhere and claiming they're false. You're showing you don't even know what the arguments are in the first place.
You are failing to distinguish between what is actually "data", i.e. the parameters of the buildings, the timing of the fall, etc., with model parameters. Of couse they did not release the LS-Dyna parameters; that's nothing but databases of figures for a specific software app. NIST went one better: They release the actual event's data. You can see what timing inputs they used. You can see what temperature inputs they used. You can see the load figures they used. NCSTAR 1-9A specifically exists to discuss all of that.
Furthermore, your complaint about "fudging" is empty. Ignoring the fact that you wouldn't know what to do with the parameters, once again, the data regarding the event along with the modeling they used is published in the NIST reports. Go ahead and point out where a part of the NIST report on building 7 does not follow from the first principles and data given. If you can do that, then you might have an argument. But not before.
On top of that, you truthers are hardly the ones in a position to legitimately complain about peer review. Your side has produced zero work that's undergone any (if you think the Bentham paper counts, you know nothing about peer review). That's the pot calling the kettle "black" in spades. You want formal peer review, submit work to an academic journal. But if you want real-world validation of the evidence - something that peer review processes are only the first step towards - go back to my posts where I point out the ASCE and ICC acceptance of the findings, and furthermore their use of the knowledge generated to modify building code. Some builders have already mounted a backlash against the code modifications due to monetary cost, and this demonstrates that not only is the knowledge accepted by engineers and architects in the industry, but that it's put to use. There's your validation. It can be found in the ASCE standards, the Eurocodes, and the ICC agenda for upcoming meetings. It can be found in Arup's designs and papers. Yes, a peer review would be nice; Dr. James Quintiere is one of the people who's suggested this. But it's not final validation; it's merely the entry step to acceptance and use in scientific fields (which is probably why the conspiracy peddling side doesn't have any: They're not competent enough to even get their feet in the door, let alone withstand any legitimate reviews that would come their way). The knowledge NIST generated has already bypassed that and been put to use. Say what you will about the lack of peer review; from an academic standpoint, I'd probably agree with you. But don't even try to pretend that the absence of such invalidates the knowledge. The code changes alone demonstrates the bankruptcy of that stance.
------
Are you going to finally start studying the real issues involved with understanding the collapses? Or are you going to simply retail the same old arguments that have been addressed time after time here? Read the NIST reports before you continue with your criticisms; you don't even have a basic understanding of the collapse progression, let alone the mechanism NIST provided. And learn something about the academic process while you're at it. You argue from extreme ignorance, and that's a terrible position to defend stances from.
Insert Picard facepalm for cmatrix's statement here: --->*<---
Gravitational potential energy does not get "used up" when a body is falling; it gets converted to kinetic energy. The act of accelerating to the ground is not a consumptive one. Do not mistake propulsion for gravitational acceleration.
Furthermore, you continually ignore the damage to the interior from the fires. Again: Columns on one side of the building were compromised by the fires, this lead to a series of floor failures ultimately leading to the buckling of many columns low in the building. And that's the reason the collapse happen to begin with: Those interior failures. The kinetic energy from the floors above those buckled columns is overcoming what little resistence is left after those columns buckle.
You continually cite the columns as if they were never 1. Part of a system that included floors and trusses, and 2. Weren't compromised by the fires and failures of the floors and trusses. You fail to understand the collapse progression, and you fail to recognize that fact. You need to study the actual events, not the truther myths about them.
No, it is what was measured. Refer to NCSTAR 1-9, table 12-2. This was measured during a study of the video.
You'd better bone up on the arguments before going anywhere and claiming they're false. You're showing you don't even know what the arguments are in the first place.
You are failing to distinguish between what is actually "data", i.e. the parameters of the buildings, the timing of the fall, etc., with model parameters. Of couse they did not release the LS-Dyna parameters; that's nothing but databases of figures for a specific software app. NIST went one better: They release the actual event's data. You can see what timing inputs they used. You can see what temperature inputs they used. You can see the load figures they used. NCSTAR 1-9A specifically exists to discuss all of that.
Furthermore, your complaint about "fudging" is empty. Ignoring the fact that you wouldn't know what to do with the parameters, once again, the data regarding the event along with the modeling they used is published in the NIST reports. Go ahead and point out where a part of the NIST report on building 7 does not follow from the first principles and data given. If you can do that, then you might have an argument. But not before.
On top of that, you truthers are hardly the ones in a position to legitimately complain about peer review. Your side has produced zero work that's undergone any (if you think the Bentham paper counts, you know nothing about peer review). That's the pot calling the kettle "black" in spades. You want formal peer review, submit work to an academic journal. But if you want real-world validation of the evidence - something that peer review processes are only the first step towards - go back to my posts where I point out the ASCE and ICC acceptance of the findings, and furthermore their use of the knowledge generated to modify building code. Some builders have already mounted a backlash against the code modifications due to monetary cost, and this demonstrates that not only is the knowledge accepted by engineers and architects in the industry, but that it's put to use. There's your validation. It can be found in the ASCE standards, the Eurocodes, and the ICC agenda for upcoming meetings. It can be found in Arup's designs and papers. Yes, a peer review would be nice; Dr. James Quintiere is one of the people who's suggested this. But it's not final validation; it's merely the entry step to acceptance and use in scientific fields (which is probably why the conspiracy peddling side doesn't have any: They're not competent enough to even get their feet in the door, let alone withstand any legitimate reviews that would come their way). The knowledge NIST generated has already bypassed that and been put to use. Say what you will about the lack of peer review; from an academic standpoint, I'd probably agree with you. But don't even try to pretend that the absence of such invalidates the knowledge. The code changes alone demonstrates the bankruptcy of that stance.
------
Are you going to finally start studying the real issues involved with understanding the collapses? Or are you going to simply retail the same old arguments that have been addressed time after time here? Read the NIST reports before you continue with your criticisms; you don't even have a basic understanding of the collapse progression, let alone the mechanism NIST provided. And learn something about the academic process while you're at it. You argue from extreme ignorance, and that's a terrible position to defend stances from.
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