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Old 18th November 2015, 11:32 AM   #41
Grizzly Bear
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Originally Posted by Notconvinced View Post
The verniage technique uses CD to remove a series of supports, which is analogous to the hypothetical removal by failure of the WTC columns of 1-2 floors as proposed by "progressive collapse" proponents.
Your case for the analogy to the WTC relies on the structural behavior in reaction to the eccentric loading induced by human intervention with hydraulics. You're trying to explain the structural behavior of the WTC as a reaction to having a series of columns "removed" by a mechanism (explosives/thermite/etc) you can't even provide evidence for.

In other words you're describing the behavior of the building as suspicious, and not even exploring the mechanism to begin with.

Originally Posted by Notconvinced View Post
The Chandler video clearly shows an example of how a building behaves once that initial layer is removed. Since the WTC didn't behave this way it shows that the WTC was structurally degraded below the "verniage" layer....
What is your reason for suggesting that the WTC should have exhibited the same behavior? Buildings constructed differently, that fail at different locations will never behave alike. It is obvious to anyone who has an elementary understanding of engineering and design.

Originally Posted by Notconvinced View Post
As I and many others over the years have stated, the upper section cannot destroy more than its own equivalent lower section.
I've usually argued against this but I'm actually curious how Tony et al actually derive this conclusion. This is such a generic statement in engineering that it's devoid of any of the thought processes a professional in the field would expect to account for
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Old 18th November 2015, 12:44 PM   #42
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Originally Posted by Grizzly Bear View Post
Quote:
Originally Posted by Notconvinced
As I and many others over the years have stated, the upper section cannot destroy more than its own equivalent lower section.
I've usually argued against this but I'm actually curious how Tony et al actually derive this conclusion. This is such a generic statement in engineering that it's devoid of any of the thought processes a professional in the field would expect to account for.
.
Worse, it also contradicts known facts, such as the Skyline Towers collapse and this Verinage:

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I AGREE


Chandler's argument contradicts physics, common sense, and know facts, and yet if he yammers about the "scientific method," the ironically named Notconvinced is quite convinced.
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Old 18th November 2015, 01:52 PM   #43
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Originally Posted by WilliamSeger View Post
.
Worse, it also contradicts known facts, such as the Skyline Towers collapse and this Verinage:
Last time I showed that to a truther he said it was probably a debunker trick and that there was so much dust that you couldn't see for certain that the collapse had progressed all the way to the ground. It's remarkable how much less conspiracy theorists can see when they don't like what they're seeing than when they do.

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Me: So what you're saying is that, if the load carrying ability of the lower structure is reduced to the point where it can no longer support the load above it, it will collapse without a jolt, right?

Tony Szamboti: That is right
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Old 18th November 2015, 05:46 PM   #44
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Originally Posted by Notconvinced View Post
The Chandler video is dead accurate, and once again your group rallies around a strawman. The verniage technique uses CD to remove a series of supports, which is analogous to the hypothetical removal by failure of the WTC columns of 1-2 floors as proposed by "progressive collapse" proponents.
No, it does not. Its been explained many times, even illustrated very well by ozeco's graphic, did you look at it?) the columns simply do not line up. In order for columns to enter into the situation in any significant way the dynamic loads will have to impinge upon the columns. Columns not in line means that the loading will be on whatever else the upper section columns manage to hit, none of which are designed to withstand those loads.

Quote:
The Chandler video clearly shows an example of how a building behaves once that initial layer is removed. Since the WTC didn't behave this way, it shows that the WTC was structurally degraded below the "verniage" layer.
Sure, in a planned, engineered and controlled fashion. Its ONE such type of controlled demolition. You and your compadres are saying an engineered, controlled demolition took place, just not THIS type.

So you strike out twice, Verinage (BTW , I see you join me in spelling it wrong. I have corrected my error) simply demonstrates that crush of a lower section, by an upper section, IS possible, but does not resemble the situation of the towers. Secondly, Verinage does not apply to the style of controlled demolition you subscribe to.

Quote:
As I and many others over the years have stated, the upper section cannot destroy more than its own equivalent lower section.
,,, and yet Chandler cites Verinage in which an upper block does exactly that.

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Old 18th November 2015, 06:17 PM   #45
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Originally Posted by WilliamSeger View Post
.
Worse, it also contradicts known facts, such as the Skyline Towers collapse and this Verinage:

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I AGREE


Chandler's argument contradicts physics, common sense, and know facts, and yet if he yammers about the "scientific method," ....
Chandler adherents claim that the upper block simply cannot, under any circumstances, destroy anything more that its equivalent in the lower section.

Skyline Towers demonstrate a building being completely destroyed by an upper section that is about 1/4 of the total structure. When a hypothesis is not borne out in reality then either reality is not what we suppose it is , or the hypothesis is in error. Generally we assume the later.
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Old 18th November 2015, 07:27 PM   #46
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Originally Posted by WilliamSeger View Post
.Chandler's argument contradicts physics, common sense, and know facts, and yet if he yammers about the "scientific method," the ironically named Notconvinced is quite convinced.
With his WTC 1 & 2 specific critiques:
Chandler
  • WTC accelerates at ~2/3 gravity (6.54 m/s/s)
  • Therefore the "lower block" is only "resisting" at an equivalent of 1/3 gravity (3.26 m/s/s)
    Conclusion: something is intervening to "remove" the supports

Reality
I did the calculation for this over 5 years ago just for demonstrative purposes:

Originally Posted by Grizzly Bear View Post
For a one floor drop:

13 stories for the North tower falling on the floor below
d=distance, g=acceleration of gravity, t=time, v=velocity
d = 0.5 g x tē


Solve for time when g=9.81 m/s2, d= 3.8 meters:
3.8=0.5(9.81)*t2
3.8=4.905*t2
3.8/4.905=t2
0.775=t2
(SQRT)0.775=t
0.88 Seconds = t

Solve for v:
VF=VI+gt
Since initial velocity is 0:
VF=gt

G=9.81 m/s2 t=0.88 seconds
VF=9.81*0.88
VF= 8.63 m/s

Now assume a floor has the capacity to stop the mass completely. (DeltaV=-8.63 m/s). Depth of the floor is assumed to be 18 inches or ~.46 meters. Find time:

d = 1/2 (Vi+Vf) x t
D= .46 meters Vi=8.63 m/s Vf=0 m/s t=?

.46=1/2(8.63+0)*t
.46= 4.315t
t= .46/4.135
t= 0.11 seconds

Acceleration:
A=deltaV/DeltaT
Since we count the direction of gravity as positive and the force required to stop the mass is in the negative direction dV=-8.63 m/s

dT=.11 seconds
A=-8.63/.11
A= -78.45 m/s2

or ~7.99 g's

But the floor doesn't have nearly the capacity to bring the mass to a stop. Meaning it fails before an 8g amplification is met. Let's find something closer:

p = momentum = m x v
m1 = mass of the top 15 stories
m2 = mass of the top 16 stories = aprox. (16/15) x m1
v1 = velocity before the additional mass is added = 8.63 m/s
v2 = velocity after the mass is added (unknown)

Momentum is conserved, so:
p = m1 x v1 = m2 x v2 = (31/30) x m1 x v2
Solving for v2:
V2=V1*(15/16)
V2=8.63*(15/16)
V2~ 8.09 m/s

We want to find DeltaT for an accurate calculation of the instantaneous acceleration caused by impact with the floor so:


d = 1/2 (Vi+Vf) x t
d=.46 meters Vi=8.63 m/s Vf=8.09m/s t=?

0.46=1/2(8.63-8.09)t
0.46=1/2(0.54)t
0.46=0.27t
t= 0.46/0.27
t= 1.7 seconds

A=dV/dT
dV=0.54 m/s dT=1.7 seconds

A=0.54/1.7
A= 0.31 m/s2

Since the direction of gravity is considered positive, the upwards direction will be considered negative here so the value for acceleration relative to the direction of gravity in this final value should read:

A=-0.31 m/s2

This means that the floor could never have offered enough resistance to the mass above to make it stop, even from a drop of one floor height. The net acceleration of the upper mass is still positive relative to the direction of gravity (9.81-0.31= 9.49 m/s2), so the mass is still descending.

It means while the maximum load amplification would be almost 8 times the static weight of the mass, significantly less was required for the floors to fail. The 8g figure is unattainable because the floor failed before it could get anywhere near that. Notice that the change in velocity to get 8g's was 8.63 m/s vs this later figure of a 0.54 m/s change (meaning it's still moving at 8.09 m/s after losing a little speed with the first floor impact).
And as I pointed out in the end:
Originally Posted by Grizzly Bear View Post
...chandlers' error is [/snipped] a problem with conservation of momentum...
Also Tony did eventually comment on it, but his continued assertion of "no dynamic loads is what prevented him all these years from properly interpreting the information.

As for Chandler, its the same assumption worded differently. He interprets the net acceleration ("G" positive acceleration - "X" negative AKA deceleration) as an indication of decreased structural capacity rather than the function of an increased dynamic load/force acting on the buildings. As I noted in my little spat back in 2010 it's a really discombobulated screw up that I'm surprised he still thinks he can get away with.

So, long story short... all ya all saying the smaller couldn't crush the bigger.... you're violating conservation of momentum by making that assertion.

ETA: Glad I found this because I was feeling too damn lazy to go and rewrite it from scratch ._.;
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Old 18th November 2015, 10:27 PM   #47
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Originally Posted by GlennB View Post
Apart from Ronan Point? Remember that? You were going to look into it, but never got back to us with your finding.

It's not the same. For one, the collapsing section of Ronan Point didn't destroy itself, it simply cascaded downward. Secondly, the RP building didn't have anywhere near the redundancy of modern structures. RP's exterior was driven downward by a blast iirc, but the core structure remained, as it was the core structure that carried the load.


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Old 18th November 2015, 10:32 PM   #48
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Originally Posted by Dave Rogers View Post
The point where a conspiracy theory becomes ridiculous is the point where sustaining it requires selective denial of reality. David Chandler and Notconvinced have clearly reached this point, because they're denying the reality of progressive collapse, a reasonably well known phenomenon which is specifically taken into consideration in building design. At this point they become slightly dangerous, because if anyone involved in building design takes them seriously people might die. Fortunately, I don't think that's very likely.



Dave

Progressive collapse may certainly occur when structures are systemically damaged, such as in earthquakes and controlled demolition. Additionally, buildings with systemic weaknesses are prone to progressive collapse, such as mud huts.

Apart from explosives, what weakened the towers beneath the impact site to the point that they would crumble like a house of cards?


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Old 18th November 2015, 10:44 PM   #49
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Originally Posted by Pinch View Post
What exactly is supposed to arrest the downward movement of a mass that increases in weight - and kinetic energy - with every floor it demolishes?? Am I missing something?

Thank you for your service, and I'm certain you're not dumb. What is intriguingly not intuitive to many (including myself for many years) is that the impact of the floors actually decreases the kinetic energy as conservation of momentum insists. The mass of the towers isnt changing, perhaps getting smaller as bits fall or are blown apart, but never getting larger. And the arresting impacts decrease the initial kinetic energy so you have a collapsing structure which cannot proceed past roughly the number of floors to have originally began decent.





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Old 18th November 2015, 10:45 PM   #50
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Originally Posted by Trojan View Post
Its the equal and opposite -- somehow in truther world, that means they 12 floors can only crush 12 floors, the mass becomes pixie dust after it is crushed ...

The mass was held all along by the design of the buildings. That's what buildings do... they support their own mass.


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Old 18th November 2015, 10:59 PM   #51
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Originally Posted by pgimeno View Post
No, it doesn't. It pushes the load-bearing walls laterally with hydraulic jacks, until they are out of the vertical and fall. No supports are removed.



http://www.formauri.es/personal/pgim...s/verinage.gif



(Edit: see e.g. this video)

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It's not too different from what we saw happening in WTC2. Once the perimeter walls were too displaced from the vertical, they could no longer bear the top load and they gave way.

Many ways to skin that cat, in principle the verniage technique removes support from a central location along the axial load. Whether the support is broken by hydraulics, bombs, airplanes, nano thermite, or 'nano-termites' doesn't matter. The lower section then crushes the upper section and vice versa. This is NOT what we saw at either WTC 1 or 2 as the falling section proceeded to both be destroyed and simultaneously appear to crush/destroy many times more building than itself. Of course since this apparition cannot be true, something else destroyed the buildings and controlled demolition is the obvious answer.

Energetically and mathematically, this fact has been obscured in formal academic writings by Bazant's missing red polygon (I can repost if you need) and concealed by NISTs ignoring of the details.


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Old 18th November 2015, 11:10 PM   #52
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Originally Posted by WilliamSeger View Post
.
Worse, it also contradicts known facts, such as the Skyline Towers collapse and this Verinage

Chandler's argument contradicts physics, common sense, and know facts, and yet if he yammers about the "scientific method," the ironically named Notconvinced is quite convinced.

In your example, do we know that the building beneath was structurally unfettered? Was it a steel frame building?


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Old 18th November 2015, 11:22 PM   #53
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Originally Posted by jaydeehess View Post
......Verinage (BTW , I see you join me in spelling it wrong. I have corrected my error) simply demonstrates that crush of a lower section, by an upper section, IS possible, but does not resemble the situation of the towers. Secondly, Verinage does not apply to the style of controlled demolition you subscribe to.

,,, and yet Chandler cites Verinage in which an upper block does exactly that.

TFFT

In the 'Verinage' example Chandler cites, the building's load is leveraged at the midpoint, which is sufficient to crush the unaldutarated building. Tower 1 was leveraged at only 15% and Tower 2 at maybe 25%. Without bombs, there's not enough material or energy to do the work required at the WTC.


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Old 18th November 2015, 11:27 PM   #54
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Originally Posted by Notconvinced View Post
TFFT

In the 'Verinage' example Chandler cites, the building's load is leveraged at the midpoint, which is sufficient to crush the unaldutarated building. Tower 1 was leveraged at only 15% and Tower 2 at maybe 25%. Without bombs, there's not enough material or energy to do the work required at the WTC.


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That is totally false, there is ample energy to fracture welds and break bolts in the towers,
with energy to spare, please show your equations.

Greening not Banzant proved that long ago!
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Old 18th November 2015, 11:30 PM   #55
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Originally Posted by Grizzly Bear View Post
With his WTC 1 & 2 specific critiques:
Chandler
  • WTC accelerates at ~2/3 gravity (6.54 m/s/s)
  • Therefore the "lower block" is only "resisting" at an equivalent of 1/3 gravity (3.26 m/s/s)
    Conclusion: something is intervening to "remove" the supports

Reality
I did the calculation for this over 5 years ago just for demonstrative purposes:



And as I pointed out in the end:


Also Tony did eventually comment on it, but his continued assertion of "no dynamic loads is what prevented him all these years from properly interpreting the information.

As for Chandler, its the same assumption worded differently. He interprets the net acceleration ("G" positive acceleration - "X" negative AKA deceleration) as an indication of decreased structural capacity rather than the function of an increased dynamic load/force acting on the buildings. As I noted in my little spat back in 2010 it's a really discombobulated screw up that I'm surprised he still thinks he can get away with.

So, long story short... all ya all saying the smaller couldn't crush the bigger.... you're violating conservation of momentum by making that assertion.

ETA: Glad I found this because I was feeling too damn lazy to go and rewrite it from scratch ._.;

Except you got it wrong, because while the first floor may not have been able to "stop" the upper section, it's kinetic energy would be significantly depleted. And the next impact would do even more "stopping" while reducing the kinetic load again.


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Old 18th November 2015, 11:48 PM   #56
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Originally Posted by Notconvinced View Post
Except you got it wrong, because while the first floor may not have been able to "stop" the upper section, it's kinetic energy would be significantly depleted.
By how much?

Originally Posted by Notconvinced View Post
And the next impact would do even more "stopping" while reducing the kinetic load again.
But the (almost) entire mass of the falling top, increased by the mass of first impacted floor, would be falling under gravity between the first and second impact, which converts potential energy to kinetic energy. Isn't that right? Have you stopped to check if perhaps the kinetic energy added between floor impacts is larger than the kinetic energy lost by the impact?
If no, are you prepared to admit you don't know if the is a net loss of kinetic energy?
If yes - care to show your work and results?

But it's good that you admit the first impact would not bring the kinetic energy to zero.
The kinetic energy arose by the top part descending through the height of one floor, right?
So you already admit that a floor impact dissipates less kinetic energy than is gained by descending through the height of one floor. In other words, the collapse has picked up net kinetic energy by falling and crushing one floor.
This does not reverse on the 2nd floor.
This does not reverse on the 3rd floor.
The falling mass picks up net kinetic energy floor by floor by floor by floor by floor by floor by floor by floor by floor (80+ times).
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Old 18th November 2015, 11:53 PM   #57
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Old 18th November 2015, 11:57 PM   #58
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Originally Posted by Notconvinced View Post
Except you got it wrong, because while the first floor may not have been able to "stop" the upper section, it's kinetic energy would be significantly depleted. And the next impact would do even more "stopping" while reducing the kinetic load again. ...
LOL, explain why kinetic energy is needed when a floor in the WTC fails when loads exceed 29,000,000 pounds.

And I ask the same question; how much kinetic energy is lost; and is it ironic; if the collapse stops by some magical BS 911 truth invokes; the floor fails instantly when the upper section hits the lower floor, even it is placed at zero velocity on the lower floor.

Why does 911 truth ban physics?
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Old 19th November 2015, 12:29 AM   #59
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Originally Posted by Notconvinced View Post
Progressive collapse may certainly occur when structures are systemically damaged, such as in earthquakes and controlled demolition. Additionally, buildings with systemic weaknesses are prone to progressive collapse, such as mud huts.
Just in case anyone was still taking you seriously, I think you've pretty well shut them down here. Progressive collapse in mud huts? Seriously? I don't think you can even understand how ridiculous that is.

Originally Posted by Notconvinced View Post
The mass of the towers isnt changing, perhaps getting smaller as bits fall or are blown apart, but never getting larger. And the arresting impacts decrease the initial kinetic energy so you have a collapsing structure which cannot proceed past roughly the number of floors to have originally began decent.
This is starting to look deliberate. How can anybody be dumb enough not to realise that the falling mass is getting larger?

I'm tempted to call Poe's Law on this.

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Me: So what you're saying is that, if the load carrying ability of the lower structure is reduced to the point where it can no longer support the load above it, it will collapse without a jolt, right?

Tony Szamboti: That is right
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Old 19th November 2015, 01:07 AM   #60
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Originally Posted by Notconvinced View Post
As I and many others over the years have stated, the upper section cannot destroy more than its own equivalent lower section. T
Originally Posted by GlennB View Post
Apart from Ronan Point? Remember that? You were going to look into it, but never got back to us with your finding.
Originally Posted by Notconvinced View Post
It's not the same. For one, the collapsing section of Ronan Point didn't destroy itself, it simply cascaded downward.
Then you need to define 'destroy', as Ronan Point collapses far further than your simple claim about collapse limits.

And if you're going to quote fundamental laws of physics to support your case you can't then get all 'No true Scotsman' about it by nitpicking about redundancy. Newton didn't mention any exceptions to his 3rd law, afaik.
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Old 19th November 2015, 03:56 AM   #61
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Originally Posted by Notconvinced View Post
Except you got it wrong, because while the first floor may not have been able to "stop" the upper section, it's kinetic energy would be significantly depleted. And the next impact would do even more "stopping" while reducing the kinetic load again.


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Nope. Wrong. Conservation of momentum kicks in. You dont lose much velocity at all with each of the floor impacts even in the most optimistic case.. The deltaV just with the first impact is -0.54 meters per second (meaning still around 8.09 meters per second as a starting velocity rather than 0) after only the first hit (using the WTC 1 case scenario). So no, theres barely any loss in kinetic energy, and in fact... there is a net gain in potential energy by the time you reach the successive floors since youre calculating for an addition 3.8 meter drop for each additional floor. The math is already part of that
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Old 19th November 2015, 07:47 AM   #62
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Originally Posted by Notconvinced View Post
Except you got it wrong, because while the first floor may not have been able to "stop" the upper section, it's kinetic energy would be significantly depleted. And the next impact would do even more "stopping" while reducing the kinetic load again.

Wow, just wow. A high school physics student would see the error in that.

Kinetic energy, or momentum , if you choose to work with it that way, both depend on velocity. The initial fall starts from an initial velocity of zero, the gravity accelerates the mass to a higher velocity.
We now move to the second impact as described, and if the first impact did not stop the mass then the velocity at second impact is that remnant velocity PLUS the gain due to gravity through second fall.

PLUS gain in falling mass due to one more level's worth of debris.

Next time consult a physics school teacher.......................or at least one that understands the subject and isn't just teaching the textbook.

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Old 19th November 2015, 08:00 AM   #63
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Originally Posted by jaydeehess View Post
Wow, just wow. A high school physics student would see the error in that.
He can't possibly be serious. There he was conceding that the stuff from the first impact only lost some KE and then went on to become part of the second impact.

eta: you edited to say much the same thing

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Old 19th November 2015, 08:08 AM   #64
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Originally Posted by jaydeehess View Post
Wow, just wow. A high school physics student would see the error in that.

Kinetic energy, or momentum , if you choose to work with it that way, both depend on velocity. The initial fall starts from an initial velocity of zero, the gravity accelerates the mass to a higher velocity.
We now move to the second impact as described, and if the first impact did not stop the mass then the velocity at second impact is that remnant velocity PLUS the gain due to gravity through second fall.

PLUS gain in falling mass due to one more level's worth of debris.

Next time consult a physics school teacher.......................or at least one that understands the subject and isn't just teaching the textbook.
why would the impact slow the velocity of the first mass upon impact? It would but it might not very much. How could it not?
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Old 19th November 2015, 08:41 AM   #65
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Originally Posted by JSanderO View Post
why would the impact slow the velocity of the first mass upon impact? It would but it might not very much. How could it not?
Sorry, but I don't understand this at all. What are you asking?
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Old 19th November 2015, 08:57 AM   #66
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Originally Posted by Notconvinced View Post
As I and many others over the years have stated, the upper section cannot destroy more than its own equivalent lower section.
Can you please explain this then?
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Old 19th November 2015, 09:12 AM   #67
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Originally Posted by GlennB View Post
Sorry, but I don't understand this at all. What are you asking?
You don't understand?

How bout this... You drop a stone on a horizontal sheet of glass. The stone shatters the glass and continues down until it comes to rest on the ground.

Did the impact and destruction of the glass slow the stone at all? (we know it was not moving at constant velocity because it was dropping)
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Old 19th November 2015, 09:16 AM   #68
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Originally Posted by GlennB View Post
He can't possibly be serious. There he was conceding that the stuff from the first impact only lost some KE and then went on to become part of the second impact.

eta: you edited to say much the same thing
Again.... this is a 10+ year old dilemma of treating the towers like completely rigid structures and ignoring localized failure and dynamic loading.

They are treating the net acceleration of the collapse front as a weakening of the structure below rather than a dynamic load force acting on the structure progressively. The error is really; really simplistic
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Old 19th November 2015, 09:31 AM   #69
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Originally Posted by Oystein View Post
By how much?


But the (almost) entire mass of the falling top, increased by the mass of first impacted floor, would be falling under gravity between the first and second impact, which converts potential energy to kinetic energy. Isn't that right? Have you stopped to check if perhaps the kinetic energy added between floor impacts is larger than the kinetic energy lost by the impact?
If no, are you prepared to admit you don't know if the is a net loss of kinetic energy?
If yes - care to show your work and results?

But it's good that you admit the first impact would not bring the kinetic energy to zero.
The kinetic energy arose by the top part descending through the height of one floor, right?
So you already admit that a floor impact dissipates less kinetic energy than is gained by descending through the height of one floor. In other words, the collapse has picked up net kinetic energy by falling and crushing one floor.
This does not reverse on the 2nd floor.
This does not reverse on the 3rd floor.
The falling mass picks up net kinetic energy floor by floor by floor by floor by floor by floor by floor by floor by floor (80+ times).

>So you already admit that a floor impact dissipates less kinetic energy than is gained by descending through the height of one floor.

^i do not admit this. After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below. Then the rapidly decreasing KE of the upper section is no longer sufficient to crush anything and the collapse is arrested.

Mud huts! = toungue in cheek for 2nd/3rd world structures without redundancy, such as readily collapse in earthquakes in Haiti, India, Mexico, etc

Gotta work today, ttyl


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Old 19th November 2015, 09:40 AM   #70
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Originally Posted by Notconvinced View Post

^i do not admit this. After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below. Then the rapidly decreasing KE of the upper section is no longer sufficient to crush anything and the collapse is arrested.

Mud huts! = toungue in cheek for 2nd/3rd world structures without redundancy, such as readily collapse in earthquakes in Haiti, India, Mexico, etc

Gotta work today, ttyl

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WRONG... the falling mass impacts the lower floor and breaks it free from the column and so it is also now falling... more falling mass... then these masses fall on the slab below... break it and then it too begins to fall and so on.

Each impact DOES slow the mass from above a wee bit... but at the same time the "compacted" mass is growing and packs more punch when it falls to the floor below. It's not acting a the sum total of all the mass above... but it's aggregating mass as it "consumes" the next floor down.
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Old 19th November 2015, 10:34 AM   #71
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Originally Posted by Notconvinced View Post
>... After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below. Then the rapidly decreasing KE of the upper section is no longer sufficient to crush anything and the collapse is arrested.
...
When the top block hits the lower block at 8.52 m/s, the new mass continues at 7.86 m/s. Not much kinetic energy is expended, in fact we could almost ignore it; because the lower floor can't hold the upper mass.
Floors only hold up themselves, the core and shell hold up each floor, and all the floors.

WWJFKD?

Special 911 truth no math physics, derived by common sense. Do 911 truth follower make this up as they go, or do they copy and paste this from the 911 truth BS book of woo physics?

"Common sense is the collection of prejudices acquired by age eighteen" - Albert Einstein

This is almost as silly as the old "fell in the path of greatest resistance", invoking the secret Truther Law of physics (Newcrapian) where things fall "in the path of least resistance".
The new law applied to avalanches; avalanches stop after the part that started the avalanche reached the equal mass below. The new law, that mass is already being carried by the structure below.
Newcrapian Physics, alive and well at 911 truth, the movement of BS.
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Old 19th November 2015, 10:48 AM   #72
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Originally Posted by JSanderO View Post
How bout this... You drop a stone on a horizontal sheet of glass. The stone shatters the glass and continues down until it comes to rest on the ground.

Did the impact and destruction of the glass slow the stone at all? (we know it was not moving at constant velocity because it was dropping)
Yes, it slowed the stone, of course. The degree of slowing would depend on the stone and the glass. Make it a small stone, small drop and sturdy glass and the glass might not break at all.

The stone had KE represented by 1/2mv2 , so when the stone fractured the glass some of the KE translated quite quickly into heat. That loss must result in loss of velocity.
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Old 19th November 2015, 10:56 AM   #73
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Originally Posted by beachnut View Post
When the top block hits the lower block at 8.52 m/s, the new mass continues at 7.86 m/s. Not much kinetic energy is expended, in fact we could almost ignore it; because the lower floor can't hold the upper mass.
Floors only hold up themselves, the core and shell hold up each floor, and all the floors.
That's what keeps being ignored by Tony et. al. Once the top section rotated beyond the columns, it could not be supported or stopped. They contend that the floors were a part of the vertical support system, which they weren't.
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Old 19th November 2015, 02:07 PM   #74
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Originally Posted by Notconvinced View Post
^i do not admit this. After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below. Then the rapidly decreasing KE of the upper section is no longer sufficient to crush anything and the collapse is arrested.
To use a technical term, bollocks. Most of what the falling mass falls on is air, and once the debris below is disconnected from the structure it's falling too. So the key point you choose to ignore is that the mass of the falling part is continually increasing, and with it its kinetic energy.

Dave
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Me: So what you're saying is that, if the load carrying ability of the lower structure is reduced to the point where it can no longer support the load above it, it will collapse without a jolt, right?

Tony Szamboti: That is right
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Old 19th November 2015, 02:13 PM   #75
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Originally Posted by Notconvinced View Post
^i do not admit this. After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below................
Simple question (actually two). Was that mass in motion prior to impact of the floor above?

Wouldn't you think it needs to be added to the mass above if it wasn't (KE wise)?
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Old 19th November 2015, 03:29 PM   #76
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Originally Posted by Notconvinced View Post
>So you already admit that a floor impact dissipates less kinetic energy than is gained by descending through the height of one floor.

^i do not admit this. After the first impact, the KE of the falling body is reduced and does not pick up additional mass because that mass is already being carried by the structure below. Then the rapidly decreasing KE of the upper section is no longer sufficient to crush anything and the collapse is arrested.

Mud huts! = toungue in cheek for 2nd/3rd world structures without redundancy, such as readily collapse in earthquakes in Haiti, India, Mexico, etc
Even if you were correct, and it should be bleeding obvious you aren't, the original falling mass is moving faster upon second impact than it was at first impact. Therefore KE and momentum have increased significantly.

If the structure was incapable of arresting first impact how the h is it going to arrest second, obviously greater, impact?

.
You say the KE of falling mass is "rapidly decreasing", but its velocity must be increasing.

Let's say we have a unit mass falling. It hits with velocity v1. It loses half that amount at first impact. At first impact KE was m(v1)2. After first impact its velocity is 1/2(v1)
It now falls the same distance as it did to first impact.
It's velocity at second impact is the gain in velocity due to gravity plus the velocity it had retained after first impact, 1.5(v1)
Its KE is m(1.5 *v1)2 or 2.25 times its original KE. Fifty percent greater velocity means more than double the KE.


I did this in my head, would have been better if I had a scratch pad. Alas my situation precludes that. I invite corrections.

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Old 19th November 2015, 03:38 PM   #77
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Originally Posted by Grizzly Bear View Post
Again.... this is a 10+ year old dilemma of treating the towers like completely rigid structures and ignoring localized failure and dynamic loading.

They are treating the net acceleration of the collapse front as a weakening of the structure below rather than a dynamic load force acting on the structure progressively. The error is really; really simplistic
Both points true.
It wasn't a couple of solid structures, it was a large system of connected structural members connected and arranged to transfer floor loads to the columns, and keep those columns from buckling.
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Old 19th November 2015, 03:44 PM   #78
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Originally Posted by Dave Rogers View Post
To use a technical term, bollocks. Most of what the falling mass falls on is air, and once the debris below is disconnected from the structure it's falling too. So the key point you choose to ignore is that the mass of the falling part is continually increasing, and with it its kinetic energy.

Dave
IMHO, mass is a red herring anyway. KE increases much greater due to increased velocity than by increase in mass.
NT completely ignored that.
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Old 19th November 2015, 03:50 PM   #79
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Originally Posted by jaydeehess View Post
Even if you were correct, and it should be bleeding obvious you aren't, the original falling mass is moving faster upon second impact than it was at first impact. Therefore KE and momentum have increased significantly.
He's ignoring the fact the mass below is actually subject to gravity and was set in motion and adds to the KE.

You question him on the obvious.................
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Old 19th November 2015, 04:10 PM   #80
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Originally Posted by DGM View Post
He's ignoring the fact the mass below is actually subject to gravity and was set in motion and adds to the KE.

You question him on the obvious.................
Hah! LOL. True.
Well, while mass increases due to more destroyed structure, its also losing some mass due to shedding off to the sides. Velocity however, of any the blodly H thing that stays within the tower footprint is increasing proportional to 'g', and increasing KE proportional to the square of v. There is a possible argument for steady state mass if shedding equals gain, but there is NO argument that velocity doesn't increase.

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