Merged New video! Architects and Engineers - Solving the Mystery of Building 7

[Zeuzzz]

Yawn.

I never said the force of gravity stopped acting on the ball, or WTC7 for that matter.

What makes no sense in your argument is the statement; "While the ball is in motion, neglecting air resistance, this is the only force acting on it."

Clearly, the ball is moving upward because of an initial force F1.

Your argument only addresses the gravitational attracting force G, gravity. You do not address the force opposing gravity. The upward force F1, which made the ball oppose gravity in the first place.

So at the point where the ball stops, we have the canceling sum of the two forces (F1, upward, and G, downward, gravitational), I'll use illustrative numbers here, (+1) + (-1) = zero.

So based on Newton's second law, this sum of the two forces, zero equals the mass M times its acceleration a. We know the mass M is a real value greater than zero, so. if 0=M x a, then a must also equal zero.

So, as I previously stated, an object that is not moving, "has no velocity or acceleration."

That condition is met when the upward force, F1, equals the gravitational force, T=zero for my purposes.

velocity = the speed of something in a given direction.

acceleration = the increase in the rate of speed of something.

So, for a time of zero duration, and a velocity of zero, there is zero increase in the rate of speed.

Thus acceleration is also zero.

Back to you sylvan8798

MM

You seem to be confusing the idea that the force that's projected the ball is constantly acting on it throughout its motion. Once the ball is projected up the only resultant force acting on it is gravity. Its kinetic energy is doing work against gravity, and its momentum from the initial force is keeping it moving upwards. At all times the downwards acceleration is 1G, even at the peak when v_y=0.

 

[sylvan8798]

Yawn.

I never said the force of gravity stopped acting on the ball, or WTC7 for that matter.

What makes no sense in your argument is the statement; "While the ball is in motion, neglecting air resistance, this is the only force acting on it."

Clearly, the ball is moving upward because of an initial force F1.

True, but that force acts in the beginning and that's it. It is not still there once the ball is moving unless you are still having your hand on the ball. The only force acting once you let go of it is F=mg.

Your argument only addresses the gravitational attracting force G, gravity. You do not address the force opposing gravity. The upward force F1, which made the ball oppose gravity in the first place.

So at the point where the ball stops, we have the canceling sum of the two forces (F1, upward, and G, downward, gravitational), I'll use illustrative numbers here, (+1) + (-1) = zero.

Not how it's done, MM.

So based on Newton's second law, this sum of the two forces, zero equals the mass M times its acceleration a. We know the mass M is a real value greater than zero, so. if 0=M x a, then a must also equal zero.

So, as I previously stated, an object that is not moving, "has no velocity or acceleration."

That condition is met when the upward force, F1, equals the gravitational force, T=zero for my purposes.

You haven't addressed the fact that having reached this point and having, according to you, no net force on the ball, the first law says it doesn't then move. Do balls just end up hanging in the air?

velocity = the speed of something in a given direction.

acceleration = the increase in the rate of speed of something.

So, for a time of zero duration, and a velocity of zero, there is zero increase in the rate of speed.

Thus acceleration is also zero.


Back to you sylvan8798

MM

Let's try another example. I take the ball up on the roof of a nearby office building. I hold it out over empty space 50 feet above the ground. I let go of the ball. The position of the ball with time is given by the equation y = y(0) + v(0)* t -(1/2)* a * t^2 where y is position in space, y(0) is the position at time t=0, v(0) is the initial velocity, a is the (constant) acceleration at all times, and t is time elapsed. Taking the origin on the ground, y(0)=50 ft. The ball falls from "rest" with no initial velocity, so v(0)=0. The acceleration a=-g since I made up be the positive direction. So y=50-(1/2) * 32.2 *t^2. If a=0 at the initial time at which I let go of the ball, it will just hang there in space.

 

[Miragememories]

If somehow you believe all your academic posturing is going to make WTC7's 100 foot free fall drop become somehow insignificant and a realistic fire-induced expectation, than good luck to you.

No posturing is needed to make it a realistic expectation in a fire-induced collapse, because it already is a realistic expectation in a fire-induced collapse. On the contrary, it's in an explosive demolition that it's extremely difficult to explain the bit whose existence you're frantically trying to deny by describing the part of the above curve where the acceleration is obviously very much less than freefall as "near freefall". And your attempts at explanation boil down to saying "That's just how they did it."

First order of business, fire-induced collapses are never an expectation for modern concrete and steel office towers and to date there is nothing but theory to support a belief that such a thing is possible.

The collapse of WTC7 from fire has never been proven beyond theory.

Of course if a person, like yourself David, wants to believe such a collapse (WTC7) is fire induced, than that is your prerogative. But it doesn't make it anymore credible.

You keep waving your pretty little curve around like it is all the NIST required to make their case.

Charts, graphs, computer simulations etc. are all examples of analysis tools that are only as good as the data that fuels them, and in the case of models, the validity of the data and the quality of the algorithms.

At any rate David, why do you keep hand waving about what you feel is my interpretation of the NIST's Stage 1?

It is Stage 2 that holds my primary interest.

Of course you don't want to discuss Stage 2 because the NIST admitted that it was a freefall stage.

A total, high speed collapse, including seconds of freefall, is a highly unrealistic expectation in a building fire, and the NIST spent 7 years wringing their hands, desperately trying to formulate a theory.

They obviously did not think a fire-unduced collapse was a realistic expectation.

A controlled demolition does explain it. Unfortunately, as we all know, the NIST wanted to avoid that scenario like the plague. They confined their investigation into controlled demolition to just the use of RDX applied to Column 79.

If they hadn't dismissed and/or ignored the eyewitness testimony about explosives, and had they looked for nanothermite residue, and proven its non-existence, the whole controversy about WTC7 would likely never have gained so much momentum.

But just like you David, the NIST did not want to find out that not all the terrorists were in the planes on 9/11.

MM

 

[Zeuzzz]

Hang on, is there a point to all this mechanics?

I've totally forgotten or original point made.

 

[ozeco41]

Hang on, is there a point to all this mechanics?

I've totally forgotten or original point made.

It's called trolling - round and round in circles progressing nowhere. The only purpose is to keep you responding to the nonsense.

MM is wrong on bits of mechanics but that is of no concern to him.

 

[Miragememories]

True, but that force acts in the beginning and that's it.

The ball has upward momentum until it stops, which is the driving force gained by the development of a process or course of events (someone tossing it).

Let's just cut the academia about balls in the sky and confine the discussion to WTC7 dropping in freefall.

We do not need to do any calculations to accept the Stage 2 freefall unless you now wish to dispute the NIST on that point as well?

MM

 

[Miragememories]

Hang on, is there a point to all this mechanics?

I've totally forgotten or original point made.

No Zeuzzz, There is no point other than a feeble attempt to draw the discussion away from the fact that WTC7 was in freefall for 100 feet.

MM

 

[LSSBB]

No Zeuzzz, There is no point other than a feeble attempt to draw the discussion away from the fact that WTC7 was in freefall for 100 feet.

MM

...because the interior debris from the fire induced collapse knocked out the bottom floors of the exterior shell. (Freefall-ish, evidently)

 

[NoahFence]

Hang on, is there a point to all this mechanics?

I've totally forgotten or original point made.

The point is to confuse the reader. MM knows full well that controlled demo of any kind played no part in 9/11.

 

[sheeplesnshills]

First order of business, fire-induced collapses are never an expectation for modern concrete and steel office towers

lie number 1 Post 911 they are likely considered a near certainty if the fire is unfought and a high risk even if they are.

"and to date there is nothing but theory to support a belief that such a thing is possible.

Lie #2 There are three very big practical examples of just that happening

The collapse of WTC7 from fire has never been proven beyond theory.

Lie # 3 No its proven fact. The exact process is a theory but the collapse is well documented fact

Of course if a person, like yourself David, wants to believe such a collapse (WTC7) is fire induced, than that is your prerogative. But it doesn't make it anymore credible.

You keep waving your pretty little curve around like it is all the NIST required to make their case.

Its you who are trying to make a case. The 1g is of little interest to anyone else as its nothing particularly unexpected.

Charts, graphs, computer simulations etc. are all examples of analysis tools that are only as good as the data that fuels them, and in the case of models, the validity of the data and the quality of the algorithms.

So? bet they are better than what you have which is zip, nada, nothing.

At any rate David, why do you keep hand waving about what you feel is my interpretation of the NIST's Stage 1?

It is Stage 2 that holds my primary interest.

Of course you don't want to discuss Stage 2 because the NIST admitted that it was a freefall stage.

againso what? just because you can't comprehend something does not mean anyone else should give a rats behind let alone NIST.

A total, high speed collapse, including seconds of freefall, is a highly unrealistic expectation in a building fire, and the NIST spent 7 years wringing their hands, desperately trying to formulate a theory.

They obviously did not think a fire-unduced collapse was a realistic expectation.

again so what? Their job was to find out how it may have happened. A difficult technical problem. Their expectations prior to 911 are utterly irrelevant as its likely they never spent much time even considering the problem.

A controlled demolition does explain it. Unfortunately, as we all know, the NIST wanted to avoid that scenario like the plague. They confined their investigation into controlled demolition to just the use of RDX applied to Column 79.

No it doesn't as there were no bangs, no timers and no explosives of any sort found nor any steelwork with signs of being cut. Without these there can can been no CD of any sort much less the massive number of charges you seem to think were used. Period. add on the evidence from the FDNY and no credible motive nor opportunity, CD is probably the least likely of cause of failure.

If they hadn't dismissed and/or ignored the eyewitness testimony about explosives, and had they looked for nanothermite residue, and proven its non-existence, the whole controversy about WTC7 would likely never have gained so much momentum.

It would have made no difference at all to twoofers. If you can deny all the other non signs of CD what would what another gov. agency say about sooper nanny thermnight would simply be hand waved away.

But just like you David, the NIST did not want to find out that not all the terrorists were in the planes on 9/11.

Who ever said they were? One was in jail and lots of others were back in Afghanistan. If they were all on the planes they would have been no hunt for OBL now would there? NISTs job was to find out how fire could have brought down WTC7. They do not pretend to say that exactly how it did happen as they had to make lots of assumptions. They could be proven completely wrong tomorrow if new data became available and it would not reflect at all badly on them.

 

[cjnewson88]

Yawn.

So based on Newton's second law, this sum of the two forces, zero equals the mass M times its acceleration a. We know the mass M is a real value greater than zero, so. if 0=M x a, then a must also equal zero.

So, as I previously stated, an object that is not moving, "has no velocity or acceleration."

MM

I'll have a go.

If gravity was not there constantly exerting an acceleration, the ball would effectively become weightless and neither fall or even decelerate from initial velocity. Therefore the argument that gravity is not accelerating on stationary objects is an impossible situation (unless you're in space).

Its easier to think of the ball sitting stationary on a table. Gravity is constantly a force (acceleration) pushing on the ball. The table is exerting an opposite force to prevent Gravity from pushing the ball through the table. If the sum of the total force was equal to 0, the ball would be weightless.

MM is getting confused as he is basing his entire argument on the false understanding that at that particular stationary time Force = 0. It does not.

 

[sheeplesnshills]

No Zeuzzz, There is no point other than a feeble attempt to draw the discussion away from the fact that WTC7 was in freefall for 100 feet.

MM

Who denied it???? what you fail to grasp is that no one competent and sane cares less. Its no more important than the fact that the building was brown in colour or that a desk in office NN313C was crushed 12 seconds after initiation.

No one cares because its not important. At best its a little exercise for an engineering 101 class to ponder before breaking for lunch.

 

[ElMondoHummus]

Hang on, is there a point to all this mechanics?

I've totally forgotten or original point made.

The point to all this mechanics is what Jay Windley said years ago:

Remember that the goal of conspiracy rhetoric is to bog down the discussion, not to make progress toward a solution. As long as conspiracy theories simply "call for more research" or assert that "it remains an open question," their proponents will continue to enjoy attention.

As we discover, the alleged "anomalies" and "inconsistencies" almost always turn out to be a failure to meet the ignorant and ill-founded expectations of the conspiracy theorists. And so it's tempting to spend a lot of time arguing whether those expectations are right or wrong. Hog-heaven for the conspiracist. By quibbling over just how wide that inductive leap is, the argument becomes endlessly subjective and fails to acknowledge that the absolute width of the leap is utterly irrelevant.

Whether one's inductive leap is trivial or strenuous is irrelevant if it's still the shortest one. That is, the theory to which we rationally subscribe is always the best theory, regardless of how objectively good it is. If the inductive leap for one theory is long, we can still hold to it if the leap in other theories is still longer.

The only meaningful challenge to one line of induction is another line of induction whose inductive leap is shorter. The question is thus not that X isn't proved sufficiently to remove the inductive leap altogether and thus reject Y categorically. It isn't that X's inductive leap is so long that you're just better off believing Y on general principles. The question -- the only proper question, that is -- is whether the inductive leap associated with Y is greater or lesser than X's leap.

That's why you never get a coherent Y out of conspiracists. That's why they'll have individual scenarios that explain individual anomalies (thermite on the steel, missiles at the Pentagon, etc.) but no coherent full-scale theory. Why? Because by giving you just bits and pieces, or by claiming they don't have or need a Y because they're only "raising issues", they don't give you anything whose inductive leap can be measured against X's.

It's blindness, for sure, but it's blindness in the sense that they don't understand why their approach will never be given equal consideration alongside a testable theory.

 

[triforcharity]

None of that is needed.

Yes, it most certainly is. Do try to follow along. If you weren't shifting those goalposts all over, you'd have more energy to pay attention.

Am I that much more intelligent than the debunkers?

Not a chance in hell.

All that is required is to use the constants in a model and develop the possible consequences of individual structural failures.

Get it? It doesn't matter how something fails because the energy that caused the failure, supposedly fire, is gone and does not assist in subsequent failures.

Do you know how many constants there are WRT fire? 1. It's hot.

Not that your comment makes any sense whatsoever.

Think stress test.

Which has nothing to do with your comment.

Do you even remember what your comment was that I am addressing?

 

[sylvan8798]

The ball has upward momentum until it stops, which is the driving force gained by the development of a process or course of events (someone tossing it).

Um, still not doing it right. "Force" is not the same things as "momentum".

Let's just cut the academia about balls in the sky and confine the discussion to WTC7 dropping in freefall.

We do not need to do any calculations to accept the Stage 2 freefall unless you now wish to dispute the NIST on that point as well?

MM

I'll take that as a concession. The point is that you lack understanding of even the most basic of physics concepts. How are you to have any credibility when you want to talk about what is basically the physics of the collapse if your understanding is so lacking? You made statements upthread which were contradicting each other, but you lack the basic understanding to even grasp WHY or HOW they contradict each other.

Once the interior columns of WTC7 were giving way, and began to buckle the exterior frames, there is no reason that they couldn't form hinges and cause a large sector to fail all at once, thus leaving the upper wall sections unsupported for some 8-10 stories until it landed on the lower parts. Only truthers claim to see this as a problem.

 

[tfk]

Sorry I feel nub for asking, but can someone explain to me why, in two places, does the green line move above 0 acceleration? Did WTC7 begin to fall upwards at some stage? or is this just representing the building is resisting G for these brief moments?

http://www.internationalskeptics.com/forums/picture.php?albumid=553&pictureid=3555

You're not a nub for asking. It's an excellent question. And it's astute of you to notice that sort of detail in curves like this, try to figure out what they mean, and ask about them if they don't make sense.

Short answer: artifacts of the data, and the embellishment below.

[Embellishment: The time on that graph between 3.5 & about 4.75 seconds represents the "Stage 1" fall. In other words, the building started to fall around 3.5 seconds on this arbitrary timeline. It is entirely possible for the extreme northwest roof line point to have undergone a positive acceleration. That does NOT mean that it moved upwards. It means that its downward velocity suddenly decreased in magnitude. And this really did happen, if you look at the curves.]

I assume that you get that the video gives you position at even increments (.0333 seconds) of time. You need a scaling factor (some known distance in the image to translate pixels into distance).

Then you divide the difference in position by the time to get the average velocity over that increment of time. (Best to place that value at the average time between t1 (1st frame) & t2 (2nd frame).

Then you do the same thing with the velocity to get the average acceleration over two successive velocity measurement.

What you get when you get done is a fairly noisy signal, and some filtering is required to tame the noise.

[Embellishment note: a bunch of the info below applied to motion of the roof line before the collapse began. This is, I believe, the source of that motion, which is not shown in this graph. Sorry, for the confusion. It's been awhile since I thought about this data.]

There are some sources of noise that femr (the originator of the data) was able to remove. Such as camera motion (by subtracting out the motion of other "fixed" points in the image).

There are some that he was not able to eliminate. Wind would have been a minor one, since the view of the building was nearly perpendicular to the wall.

But one that he did not address, and possibly could not address, was diffraction of the light coming from the roof line thru the hot gasses emanating from the building.

Just like hot ground causes images to shimmer (i.e., move around), the very hot gasses emanating from the building would have caused the roof line to appear to jump around, and this would appear as (false) velocity & accelerations.

I believe this to be the most likely cause of those excursions.

Note that they may also be artifacts of the substantial filtering that was required to tame a lot of noise in the position signals.


The positive accelerations were the result of the downward velocity suddenly decreasing. This point on building started to collapse, and then something caught & held it for a short period, before the collapse continued. [Added. tk]


tom

 

[sylvan8798]

Sorry I feel nub for asking, but can someone explain to me why, in two places, does the green line move above 0 acceleration? Did WTC7 begin to fall upwards at some stage? or is this just representing the building is resisting G for these brief moments?

[qimg]http://www.internationalskeptics.com/forums/picture.php?albumid=553&pictureid=3555[/qimg]

I would just point out also that a positive acceleration as shown on the graph doesn't necessarily suggest that the building was falling upwards. Think about it this way: If an object is falling down and has an acceleration in the SAME direction (down) then it speeds up. If it is falling down and has an acceleration in the OPPOSITE direction (up) then it would slow down. In general the rule is if v and a are in the same direction, the speed increases. If v and a are in opposite directions the speed decreases.

So the points in question could be artifacts due to the difficulty of taking data from pixilated videos, or it's possible they could be indications where the collapse slowed briefly due to resistance from the intact structure below (don't let any truthers hear me say that ).

Cross posting with tfk.

 

[beachnut]

...
The collapse of WTC7 from fire has never been proven beyond theory.

...
MM

Proof seen on 911, full scale model of WTC 7 on fire and collapsed. Proof for rational people, but 911 truth followers can't connect the dots. You missed it.

I don't know a building that survived fires not fought, no water available. Do you? Windsor Building, fire fought, building totaled. One Meridian Plaza, fire fought, building gone. Even fires fought do not mean buildings survive.

AE nuts failed to solve 911, and will no hope solving WTC 7 until they gain knowledge and see Gage's claims are nuts.

 

[tfk]

I would just point out also that a positive acceleration as shown on the graph doesn't necessarily suggest that the building was falling upwards. Think about it this way: If an object is falling down and has an acceleration in the SAME direction (down) then it speeds up. If it is falling down and has an acceleration in the OPPOSITE direction (up) then it would slow down. In general the rule is if v and a are in the same direction, the speed increases. If v and a are in opposite directions the speed decreases.

So the points in question could be artifacts due to the difficulty of taking data from pixilated videos, or it's possible they could be indications where the collapse slowed briefly due to resistance from the intact structure below (don't let any truthers hear me say that ).

Cross posting with tfk.

Nice catch, sylvan. I'm still at work, trying to finish up some other stuff, and weren't thinkin to gud...

 

[Zeuzzz]

Are the two instances of slightly more than 1G acceleration of the collapse likely instances when a) the structural resistance was at a minimum plus b) the internal core column(s) that had already failed actually provided a very slight downwards force by pushing down on horizontal supports?