Merged Freefall is not evidence for Controlled Demolition

[ozeco41]

Sure but, what does this have to do with the argument that free-fall means CD.

It is a valid starting pont to understanding the principles involved.

IMNSHO

Why bother with this "hypothetical"?

Step by step learning process. It is where he wants to start. It is as good as any I think.

...for a learning process not a "bare fists argument with a truther"

 

[jaydeehess]

Being not too humble I should point out that in post 412 I noted that the velocity of the point on a rotating beam changes from downward to upward. Given that acceleration is also a vector there must also be a changing acceleration.

 

[Reactor drone]

Again, my scenario:
If a building -- WTC7 or any other -- is observed to collapse on all sides at the same/virtually the same/very nearly the same time, would that not mean that all of the structural support must have given way at the same/virtually the same/very nearly the same time?

For the WTC buildings "very nearly the same time" is correct(for certain values of very nearly the same). Rapid progressive failures are, by definition, rapid. Once the buildings structure reaches the point of failure it's a "straw that breaks the camel's back" scenario, one section overloads, that load is transferred to the next section which overloads and so on. With every piece that fails there's less capacity to take the transferred load and the rate of failure accelerates.

Where most CD proponents fail is not understanding how fast the process can be so they see a need to help it along with explosives.

 

[ozeco41]

Being not too humble I should point out that in post 412 I noted that the velocity of the point on a rotating beam changes from downward to upward. Given that acceleration is also a vector there must also be a changing acceleration.

Yes.

From which part of the rotational motion do we get an acceleration which adds to the "whole body in free fall (at near enough to) G" so that we get a point ACCELERATING at "over G"?

So can we take the rotating beam as proof of a source of "over G"?

Can we take the falling beam with cup <> falling ball "race model" as proof of "over G"?

Are the two models - beam/cup v ball AND rotating beam - examples of the same vector addition?

 

[alienentity]

I posted: "If a building -- WTC7 or any other -- is observed to collapse on all sides at the same/virtually the same/very nearly the same time, would that not mean that all of the structural support must have given way at the same/virtually the same/very nearly the same time?"

Yes, I think it would. That's all I can add to it as a hypothetical.

 

[GlennB]

I posted: "If a building -- WTC7 or any other -- is observed to collapse on all sides at the same/virtually the same/very nearly the same time, would that not mean that all of the structural support must have given way at the same/virtually the same/very nearly the same time?"

It would mean that all the structural support of those sections that we can see falling haa dropped to zero at much the same time. Once again you're equating 'what we can see' with 'a building', whether it's WTC7 or some generic building.

 

[jaydeehess]

Yes.

From which part of the rotational motion do we get an acceleration which adds to the "whole body in free fall (at near enough to) G" so that we get a point ACCELERATING at "over G"?

So can we take the rotating beam as proof of a source of "over G"?

Can we take the falling beam with cup <> falling ball "race model" as proof of "over G"?

Are the two models - beam/cup v ball AND rotating beam - examples of the same vector addition?

We get this additive acceleration only because we are looking at a single point on the beam.
Yes the falling beam/cup is analogous, though in that case the axis of rotation is not the CoM.

Now make it more complex.
Using the beam rotating about a point at one end of the beam(the beam/cup model). The axis of rotation is fixed at the ground. As it begins to rotate it builds up rotational momentum. That momentum will be conserved if the system is changed.
Now the bottom drops out. The previously fixed axis of rotation is no longer there, and the beam begins to fall under gravity while that rotational momentum also must be preserved. But it cannot now be rotating about the same axis, instead it must now rotate about its CoM.

So its still rotating, but also falling. The rotation is now as it is for a free body beam. The whole system falls with the CoM moving at 'g' but the end points of the beam are not.

This is still an idealization of the exterior of WTC 7 as it was not unaffected by other structure, it was not a single column, however it was rotating with the lower end moving to the north and the upper end moving south.

To be sure, I actually believe that the proposal by LSSBB et al of a pull down by other structure would contribute more to the acceleration of the exterior than would rotation.

But what have we here? The OP queries the idea of FFA=CD.
This is brought about by the claim by Chandler, backed by an organization of supposedly 2000 architects and engineers.
However, the first thing that one notices is that 'g' was not the limiting factor here. If all that was in effect was gravity and this was a strict vertically falling body then 'g' would be a limiting factor.
Therefore, since the points measured achieved greater than 'g' it stands to reason that other factors were involved in the acceleration of the exterior of WTC7.

That fact already establishes that Chandler's (AE911T) claim is in error as he has not accounted for all factors and has treated this as if it is a strictly vertically falling free body. If other factors could create additional acceleration then unless he can identify those and show that they too can only be achieved with CD, his claims do not stand. Though this group has actually never backed the bald claim that FFA is achievable only by demolitions in any way shape or fashion.

In first approximations the posters on JREF have identified two possible contributing factors of added acceleration, pull down by previously collapsed structure, and rotation of the exterior.

These then also destroy the claims by Chandler (AE911T).

 

[jaydeehess]

If a building -- WTC7 or any other -- is observed to collapse on all sides at the same/virtually the same/very nearly the same time, would that not mean that all of the structural support must have given way at the same/virtually the same/very nearly the same time?"

Its a case of free body falling in a gravity well. Its no different than saying you have a mass suspended by a tether, cut the tether and it drops at 'g'.

Put the mass on a column, remove the column, mass drops at 'g'.

Put a mass on x number of columns and remove all columns at once, the mass falls at 'g'.

Call the mass a building, and say that the columns are removed very quickly............. doesn't change much other than moving away from the idealized situation.

 

[Richard the G]

Yes and no.

It does mean that the structural system is offering almost zero effective resistance.

Let me ask this by way of a demonstration. What makes a concrete chimney collapse vertically, at nearly freefall speed, rather than fall over? Its easy: when concrete is overloaded in compression there is an explosive failure ( no explosives). The amount of time it takes the concrete to reach its failure load is milliseconds, at which point the next failure occurs. So it appears that the concrete below offers no resistance, but it does, its just not significant.

Similar thing happens when a 15 story wall, drops on a beam to column connection below. It slices through it in a millisecond, and then what happens when 16 stories of floor...etc etc

The (no explosives) are in case you are a truther as they tend not to understand. What do you think?

Take you time David but would be interested in your views

 

[david.watts]

Response

Its a case of free body falling in a gravity well. Its no different than saying you have a mass suspended by a tether, cut the tether and it drops at 'g'.

Put the mass on a column, remove the column, mass drops at 'g'.

Put a mass on x number of columns and remove all columns at once, the mass falls at 'g'.

Call the mass a building, and say that the columns are removed very quickly............. doesn't change much other than moving away from the idealized situation.

jaydeehess: That describes very well, and very simply, what I was trying to describe.

 

[david.watts]

To ozeco41: "I have been crystal clear what your question was from my first responses (posts #366, #388, #393)."

Yes, I was well aware you were "crystal clear." And we are in agreement on all of the things you stated. And, you are "crystal clear" the way you state things. Thank you.

 

[david.watts]

To alienentity: "Yes, I think it would. That's all I can add to it as a hypothetical." Its looks like we are in agreement as far as the basic (starting point) premise.

 

[ozeco41]

To ozeco41: "I have been crystal clear what your question was from my first responses (posts #366, #388, #393)."

Yes, I was well aware you were "crystal clear." And we are in agreement on all of the things you stated. And, you are "crystal clear" the way you state things. Thank you.

 

[david.watts]

For the WTC buildings "very nearly the same time" is correct(for certain values of very nearly the same). Rapid progressive failures are, by definition, rapid. Once the buildings structure reaches the point of failure it's a "straw that breaks the camel's back" scenario, one section overloads, that load is transferred to the next section which overloads and so on. With every piece that fails there's less capacity to take the transferred load and the rate of failure accelerates.

Hard to argue with what you stated. (note: I hope I don't end up arguing you with what you stated.)

 

[david.watts]

It would mean that all the structural support of those sections that we can see falling haa dropped to zero at much the same time. Once again you're equating 'what we can see' with 'a building', whether it's WTC7 or some generic building.

Valid point. So, for the hypothetical, let's pretend we have an all-seeing eye; not that we can see in more than 3 dimensions, but at least we can see all 4 sides plus the roof.

 

[GlennB]

Valid point. So, for the hypothetical, let's pretend we have an all-seeing eye; not that we can see in more than 3 dimensions, but at least we can see all 4 sides plus the roof.

Then some mechanism is in play which reduces all support over a certain # of storeys (the observed ~freefall height) to a negligible level, as others have described.

But - and this is a fact of life - if CD with explosives is being proposed to explain this then you will need a lot of bangs and flashes happening.

 

[david.watts]

Yes and no.

It does mean that the structural system is offering almost zero effective resistance.

Let me ask this by way of a demonstration. What makes a concrete chimney collapse vertically, at nearly freefall speed, rather than fall over? Its easy: when concrete is overloaded in compression there is an explosive failure ( no explosives). The amount of time it takes the concrete to reach its failure load is milliseconds, at which point the next failure occurs. So it appears that the concrete below offers no resistance, but it does, its just not significant.

Similar thing happens when a 15 story wall, drops on a beam to column connection below. It slices through it in a millisecond, and then what happens when 16 stories of floor...etc etc

The (no explosives) are in case you are a truther as they tend not to understand. What do you think?

"It does mean that the structural system is offering almost zero effective resistance." Interestingly stated. A play on words/phrases: "offering almost zero effective resistance" could, I suppose, also mean, "offering almost total ineffective resistance." And, why do you think truthers don't understand yet -- by implication -- non-truthers do understand? Is it really because truthers are dumber than non-truthers? Or is something else in play?

(note: short search but, I could not find anything on "concrete chimney collapses.)

 

[Richard the G]

"It does mean that the structural system is offering almost zero effective resistance." Interestingly stated. A play on words/phrases: "offering almost zero effective resistance" could, I suppose, also mean, "offering almost total ineffective resistance." And, why do you think truthers don't understand yet -- by implication -- non-truthers do understand? Is it really because truthers are dumber than non-truthers? Or is something else in play?

(note: short search but, I could not find anything on "concrete chimney collapses.)

Not trying to play with words, not a game, just trying to be precise.

So you understand what I am saying and you don't understand why truthers don't. I think its because they don't want to. The mystery of conspiracy is more appealing to them than the mystery of science.

That's why only 0.02% of engineers have signed the petition because the majority are interested and understand the basic science, even the complex science.

Sorry you couldn't find the chimney, suggest that you try harder if you want to find the truth.

 

[LSSBB]

Valid point. So, for the hypothetical, let's pretend we have an all-seeing eye; not that we can see in more than 3 dimensions, but at least we can see all 4 sides plus the roof.

Another clarification is in order: Is there another driving force present, such as the building interior collapsing first and applying compressive pressure to the outside? That would have a bearing on whether the resistive force at the bottom was zero, or just counterbalanced.

Also, if the interior is collapsing first, is that collapse uniformly distributed?

One more question: does the building have to have a moment frame construction?

 

[beachnut]

Hard to argue with what you stated. (note: I hope I don't end up arguing you with what you stated.)

Why do you not have a 747 type rating? Is there one?

How will you back in CD with this?

You already think you have.
http://www.opednews.com/Diary/9-11--NIST-Provides-the-P-by-David-Watts-090104-77.html
But it is nonsense.
http://www.sxolsout.org.uk/DavidWatts.html
More nonsense, now 5 years stale BS. CD failure, only true in the minds of 911 truth followers.
At least you have, "Jesse Ventura just came out and said the three building collapses on 9/11 were controlled demolitions." Breaking news, the engineering expert Jesse said so? Oh, he is not an engineer? Darn.

http://www.opednews.com/author/author10429.html
An author of woo said...

Given that it takes at least weeks to plan and prepare a building like WTC7 for a controlled demolition; and given that there is no reason to believe anyone other than "insiders" could have carried out the advanced preparation and actual execution of the controlled demolition of the secure WTC7 ("CIA Building"); therefore the controlled demolition of WTC7 was carried out by "insiders."

Given that WTC7 was brought down on 9/11; and given that there could be no reason to demolish WTC7 other than to be included with the other events on 9/11; therefore "insiders" also planned and executed the other events on 9/11, i.e., 9/11 was an inside job .


Thank you NIST for providing the proof that 9/11 was an inside job / false flag attack.

911, the inside job fantasy for conspiracy theorists. 12 years of nonsense. Could have had a PhD, but all they have is woo.
How will making up scenarios which do not match what happened on 911, help you rationalize the CD fantasy? Do the engineers here have to forget their training? Do the skeptics have to abandon logic and critical thinking skills to accept the woo from 911 truth CD fantasy pushers?

For 911 truth disciples quote mining is used instead of engineering, math, and physics. Most of the energy used in CD to destroy buildings is from energy stored in the building, gravity is the key along with mass and height; E=mgh. But in 911 truth gravity is ignore and we hear the dumbest claims in history from people who can't do physics, and one of the leaders is a failed physics teacher, misleading the disciples of a failed movement based on lies, and ignorance.
When 911 truth brings out the "Breaking the Laws of Physics" card, how dumb do you have to be to fall for it? That is the dumbest slogan. It debunks 911 truth.


http://www.opednews.com/Diary/9-11-NIST-Heavy-Dust-Brou-by-David-Watts-080216-204.html
I love it when 911 truth takes the biggest loser of all time, and quotes him to support their failed logic, and silly fantasy of an inside job, and CD. Quotes from Hitler make all failed movements dumber. Good job. The quotes from works of fiction are cool too; makes the movement more fiction like.

David Watts - WTC7 was a TALL, NARROW, massively braced steel-framed build: WTC7 was a TALL, NARROW, massively braced steel-framed building. For such a TALL, NARROW building to come down in such a precisely symmetrical fashion -- vs. falling off to the side -- and DIRECTLY into its own footprint at about the speed of a falling brick; common sense would say that would be impossible; unless of course, it had a lot of demolition help.

Symmetrical? That is funny, you adopted all the silly comments from 911 truth followers, and offer zero engineering, only talk. Now you want to lead skeptics into woo with failed claims, scenarios which don't match, to support your failed logic. Why is part of WTC 7 outside its own footprint? Was that a lie you were pushing? Have you retracted the silly parts of your fantasy?

You can't make this stuff up.

David Watts - Are you honestly serious when you say not the "slightest bit of evidence?" Trust me, if there were no evidence, there would be no 911truth movement.

Oops, there is no evidence, and there is a 911 truth movement, kind of, but it is a vapor movement, or a travel club for Gage.

Physics, is not used by 911 truth.

David Watts - 7. Physical laws -- the kinds of laws Isaac Newton discovered and which govern our universe --were violated on 9/11: The law of falling objects following the paths of least resistance; the law of conservation of momentum; the law of conservation of angular momentum. According to conservation-of-momentum laws, the block of approximately 34 floors on top of the South Tower should have continued to topple and fall through the path of least resistance: the air.

Falling objects move sideways to avoid hitting stuff, so they remain in air? what? Physics, 911 truth, are not talking.

When is the big story of CD going to break and earn the Pulitzer? Skeptics want to know. When?