Open Letter to Dave Thomas

[cmatrix]

You haven't the slightest clue what you are talking about.

"Can't fall faster than g" describes the falling of an object under the influence on just one force: gravity. That means "untouched by any other object and subject to no other forces."

Well, the collapsing north wall of WTC7 was NOT "an object untouched by any other object and subject to no other forces." It was a portion of a far, FAR more complex system than that. It was subject to many hundreds of forces from its connection (on the far side) to the already collapsing building.

Because of those connections & forces, it is NOT impossible for it to fall at "g". It is not impossible for it to fall faster than "g".

It appears evident that, for a brief period of time, it DID fall faster than "g".

And violated not one, single law of the universe in doing so.


Neither you, nor the high school physics teacher (Chandler), seem capable of recognizing this fact.

Your hiding your head in the sand, your deciding that I'm only spewing misdirection, & your lack of understanding don't change the real facts of the issue one iota.

It just makes you (& Chandler) look like a couple of incompetents.


tom

Nice try but I can see right through your obfuscation. NIST's progressive collapse theory requires more gravitational potential energy than could have been available. It is NIST's crackpot theory that violates the laws of physics not WTC 7. In other words, it is indeed impossible for a purely gravity driven collapse to experience any period of free fall. You can wave your hands, insult and misdirect all you want but you can't run away from this simple fact. You are supporting NIST's unreplicated, faith-based, crackpot, pseudo-science theory. You are making the extraordinary claim, not me. It is you that must produce the extraordinary proof, not me. Pronouncements are not facts and wild speculation is not proof.

 

[Dog Town]

Pronouncements are not facts and wild speculation is not proof.

 

[beachnut]

... NIST's progressive collapse theory requires more gravitational potential energy than could have been available....

backed up with... Stand by, this is BIG

... It is NIST's crackpot theory that violates the laws of physics not WTC 7.....

Nonsense backed up with nothing; Got numbers to go with your moronic delusion of CD?

No, you have pronouncements...

... Pronouncements are not facts and wild speculation is not proof.

And this is true, you debunked yourself. Welcome to JREF

 

[Newtons Bit]

Nice try but I can see right through your obfuscation. NIST's progressive collapse theory requires more gravitational potential energy than could have been available. It is NIST's crackpot theory that violates the laws of physics not WTC 7. In other words, it is indeed impossible for a purely gravity driven collapse to experience any period of free fall. You can wave your hands, insult and misdirect all you want but you can't run away from this simple fact. You are supporting NIST's unreplicated, faith-based, crackpot, pseudo-science theory. You are making the extraordinary claim, not me. It is you that must produce the extraordinary proof, not me. Pronouncements are not facts and wild speculation is not proof.

Where's your analysis showing that it "requires more gravitational potential energy than could have been available"?

 

[Dave Rogers]

All 58 perimeter columns had to be cut precisely so that the building would fall straight down.

Since it didn't fall straight down, then, we know that all 58 perimeter columns weren't cut simultaneously. This objection is therefore irrelevant.

Some of the columns in the middle could be cut a fraction of a second from the others but the rest had to be cut so close together that the time difference couldn't even be measured. It is impossible for fire to be so meticulously precise.

However, it wasn't fire that caused the failure to propagate, as any competent structural engineer will tell you. It was load redistribution which progressively overloaded and failed each structural member adjacent to the most recent failure. This objection is also, therefore, irrelevant.

A "chain of causality" requires gravitational potential energy which you don't have in free fall.

Since the progressive failure occurred, as everybody has been telling you and you've been refusing to hear, before the period of free fall, this objection too is irrelevant.

Your theory is extraordinarily ridiculous and therefore requires extraordinary proof. A true skeptic would know that. You have absolutely no proof to support your theory whatsoever.

The collapse initiation and progression was modelled in detail by NIST, and the visible features of collapse are indicative of progressive failure initiating in the eastern core columns, progressing laterally through the core, then to the centre of the north face, then laterally through the north face. All this is evidence for progressive collapse caused by fire. There is not only a complete absence of evidence for any other means of collapse initiation, there is evidence against it in the absence of explosions from the audible record.

So, since you're rejecting a theory that is based on all the available evidence in favour of one that is specifically contradicted by a subset of the available evidence, the message everyone's trying to get across to you is... actually, I think someone said it better than I can:

All you have is faith. Faith-based theories are crackpot pseudo-science. This is something you all need to come to terms with.

Next time you say that, record it and play it back to yourself, then you'll be saying it to the person who really needs to hear it.

Dave

 

[dafydd]

All 58 perimeter columns had to be cut precisely so that the building would fall straight down. Some of the columns in the middle could be cut a fraction of a second from the others but the rest had to be cut so close together that the time difference couldn't even be measured. It is impossible for fire to be so meticulously precise. A "chain of causality" requires gravitational potential energy which you don't have in free fall. Your theory is extraordinarily ridiculous and therefore requires extraordinary proof. A true skeptic would know that. You have absolutely no proof to support your theory whatsoever. All you have is faith. Faith-based theories are crackpot pseudo-science. This is something you all need to come to terms with.

Show us the math.

 

[tfk]

cm,

Nice try but I can see right through your obfuscation.

Nice try, kid.

You're bluffing.

You know it.
I know it.

NIST's progressive collapse theory requires more gravitational potential energy than could have been available.

Pure, baseless assertion.

The funny thing is that you ain't that far off in your pure, baseless assertion.

But I bet that you have no idea how to make your case.

Let's see you prove me wrong.

[BTW, lest you get all atwitter with my comment, in engineering, we have a term for a conclusion that "ain't that far off". It's referred to as: "wrong".]

It is NIST's crackpot theory that violates the laws of physics not WTC 7. In other words, it is indeed impossible for a purely gravity driven collapse to experience any period of free fall.

Here's a purely gravity driven collapse that experiences a period of acceleration GREATER than free fall.

http://www.youtube.com/watch?v=BV7TPvk__kE

Notice how much faster the free end of the lever falls compared to the ball (which is falling at 'g'.) The end of the lever is falling faster than 'g'.

Here's another, similar case:
http://www.youtube.com/watch?v=NFJPQLhWPvA

The washers are falling at 'g'. The end of the stick is falling faster than 'g'.

Whaddaya say to that, kid?

Does this simple demonstration "violate the laws of physics"?
Or is it just possible that your understanding of some of the finer details is a little, shall we say, "incomplete".

Perhaps you've put a little too much faith in people whose understanding is also a little less than complete.

You are supporting NIST's unreplicated, faith-based, crackpot, pseudo-science theory.

"unreplicated"?? Yup. You got $500 million you want to put into building, & then destroying, another WTC7? No? Well, no problem. In engineering (that'd be REAL engineering), we don't have to do that anymore. IF you had paid attention, you might have learned a bit from the NIST report (or the Challenger or Columbia investigations, or the design of any car or plane today) that computer modeling (supported by piecemeal validation of subsystems) takes the place of the destruction of full scale models. Oh, for the last 30 years or so.

That would be "computer simulations (supported by piecemeal validation of subsystems)" exactly like NIST performed.

"faith-based"? Did they use the Catholic or the Protestant version of ANSYS? Did they enter the "Jewish yield strengths" or the "Muslim yield strengths" for the steel? LoL.

"crackpot"? Sure. "Crackpot" affirmed by Purdue, MIT, Cornell, ARA, Arup, AIAA, and engineers around the globe. "Crackpot" negated by putzes like ?? You? Chandler? Szamboti? (gimme a break...!)

"pseudo-science"? Let's see you answer the questions above before we get to that one.

You are making the extraordinary claim, not me. It is you that must produce the extraordinary proof, not me.

It's not "extraordinary claims". It's "ordinary claims".

It's not "extraordinary engineering". It's "ordinary (actually excellent) engineering".

It's not "extraordinary proof". It's ordinary, competent proof, called "the NIST report".

Pronouncements are not facts and wild speculation is not proof.

Others have already comments on the irony in this one.

You can wave your hands, insult and misdirect all you want but you can't run away from this simple fact.

I'm not running away from anything, kid.

Let's see you do the same. Stay here and answer the points that I've made.

Or run away and show yourself to be wrong, a coward, and a hypocrite.

C'mon, matrix. Every single time that you've started down this path, and I've responded to you, you simply run away.

Show some huevos. Stand and defend your wild speculation & baseless pronouncements.

Or run away.

Again.


tom

 

[DaveThomasNMSR]

...
Here's a purely gravity driven collapse that experiences a period of acceleration GREATER than free fall.



Notice how much faster the free end of the lever falls compared to the ball (which is falling at 'g'.) The end of the lever is falling faster than 'g'.

Here's another, similar case:


The washers are falling at 'g'. The end of the stick is falling faster than 'g'.

Whaddaya say to that, kid?

Does this simple demonstration "violate the laws of physics"?
Or is it just possible that your understanding of some of the finer details is a little, shall we say, "incomplete".

Perhaps you've put a little too much faith in people whose understanding is also a little less than complete.
...
tom

That was freakin' awesome! I used it in my science/pseudoscience class this afternoon.

Many thanks, Dave

 

[excaza]

I remember doing that experiment in my physics class when I was a junior in HS, made my brain hurt.

 

[ergo]

Here's a purely gravity driven collapse that experiences a period of acceleration GREATER than free fall.

http://www.youtube.com/watch?v=BV7TPvk__kE

Notice how much faster the free end of the lever falls compared to the ball (which is falling at 'g'.) The end of the lever is falling faster than 'g'.

Here's another, similar case:
http://www.youtube.com/watch?v=NFJPQLhWPvA

The washers are falling at 'g'. The end of the stick is falling faster than 'g'.

Um, how is the metre stick falling faster than 'g'?

 

[beachnut]

Um, how is the metre stick falling faster than 'g'?

You saw it. What say you? Did you miss the ball floating at g?

The end of the stick is falling faster than 'g'.

ergo, where did you go?

 

[DaveThomasNMSR]

Um, how is the metre stick falling faster than 'g'?

You know, that's a pretty difficult and complicated question. I mean, you'd actually have to watch and understand the video to be able to "get" it.

So, I'll try to state it as a simpler, but equivalent, proposition.

In this picture:


Are the red lines next to A (earlier in the collapse) closer to each other than the red lines next to B (later in the collapse)?

If so, and since the the Ball (the upper object in both snapshots) is clearly falling at freefall acceleration, g, what does that mean...?

 

[TJM]

what does that mean...?

Uh, Mr. Thomas sir?

In my experience you should never ask a truther that.

 

[ergo]

The question was, how does the stick fall faster than g? Not how does it fall faster than the ball.

In other words, by what physical law would the stick be falling faster than g?

 

[tfk]

That was freakin' awesome! I used it in my science/pseudoscience class this afternoon.

Many thanks, Dave

Dave,

Glad you liked it.

I've posted it several places as a demo that things aren't as simplistic as they are often portrayed. [It surprises me when someone hasn't seen it.]

To be clear, I do believe that the evidence from a frame by frame analysis of the video that the north wall does show two brief excursions "faster than g". I believe that the integrated average acceleration over the 2 second interval is closer to 0.93G than to 1.0G.

This is obviously a possible mechanism to explain that, but I do NOT believe that it is a likely one. It merely demonstrates that real collapsing structures (even one as trivially simple as these levers) follow valid, Newtonian rules that are more complex than "free falling objects".

The reason that I don't believe that this effect occurred in WTC7 is that, in all these cases, there has to be a significant rotation of a Class 2 lever about a supported fulcrum point near one end of the lever. That rotation is essentially pulling downward on the portion of the structure that is falling faster than g.

viz., If one were to slice the assembly at the bottom of the cup catching the ball, or near the end of the lever, & draw a free body force diagram on the bottom of the cup or the side of the sliced end of the ruler, then this internal force generated by the rotation of the rigid structure would be exactly the extra downward force that, when added to gravity, causes that portion of the structure to fall faster than g.

There is no indication (that I've seen) of significant rotation of the north wall, and this should have been visible if this sort of action had occurred.

A far more likely explanation is debris falling on the transfer beams attached to the wall near the bottom. We know that the core collapsed earlier than the external wall buckled. We know that much of that debris from the collapsing cores are going to impact on transfer beams & girders that are attached to the North wall. It is not surprising in the least that the impacting material, which has had several seconds of falling to gather momentum, would put significant downward force on these horizontal beams & girders, that would then be transferred to the bottom of the north wall.

The magnitudes of these forces (0.2 to 0.4 mg) are comparatively small enough that it is not surprising that they be transmitted thru the structure of the wall without tearing it apart.

The germane point, here, is that Chandler, in making his "falling at g means zero resistance" pronouncements is talking about free body systems that have none of these highly probable (virtually certain, IMO) additional downward forces (from impacts) that occur on the far side of the north wall.

Just my $0.02.


tom

 

[DaveThomasNMSR]

The question was, how does the stick fall faster than g? Not how does it fall faster than the ball.

In other words, by what physical law would the stick be falling faster than g?

Ah, I see you don't understand the Transitive Property of Fastness.

The ball is falling at freefall acceleration, which is sometimes referred to as "g" (g is for gravity).

So, the ball is falling at g. Not faster than g, and not slower, but right there, at g.

Now, the end of the stick is clearly falling faster than the ball.

Recap:
The ball is falling at g.
The stick's end is falling faster than the ball.

So, the stick's end is falling faster than g.

See, that wasn't so hard, was it?

What physical Law would explain this? The laws of motion, and of energy conservation, will do quite nicely. Look under "kinetics" or "physics" to find more. You will also need to learn about the concepts of torque and moment of inertia.

 

[tfk]

Um, how is the metre stick falling faster than 'g'?

It's not.

A PORTION of the stick (the end of it) IS falling faster than g.

The video of the north wall of WTC7 does not show the whole structure. It shows a PORTION of the whole structure.

See the explanation in my post above. You should be able to work out the details as they apply to WTC7 from that.



tom

 

[TJM]

You should be able to work out the details

Uh, Mr. tfk sir?

 

[tfk]

Uh, Mr. tfk sir?

Yes? The eerie looking gentleman from San Francisco ...


tom

 

[Dave Rogers]

The question was, how does the stick fall faster than g? Not how does it fall faster than the ball.

In other words, by what physical law would the stick be falling faster than g?

The answer, put as simply as possible, is that the average acceleration experienced by the stick is g. Since, however, some parts of the stick are restrained so that they accelerate less than g, some other parts must be accelerating more than g.

The physical laws involved are those of gravity, leverage and geometry.

Dave