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Old 3rd April 2016, 01:12 PM   #161
beachnut
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Originally Posted by kjr63 View Post
Thank you.

If you increase mass 5% and lose speed 5%, energy decreases.
Wow, but the speed at the next impact is greater... and the last speed decrease is .91 percent... at ground level...
A floor in the WTC can only hold 29,000,000 pounds statically...
Thus the velocity can go to zero, and the next floor fails until the mass gets to the ground.

The fact is we can use BS physics and say each impact stops, but the floor fails due to being overloaded, and ignore reality the lower floor fails instantly.

Are you a CD truther, or bad at physics. Yes, 5 percent is right, but you failed to realize the velocity after the first impact is 7.86 m/s with the new mass, and the energy is almost the same; are you saying energy was lost? How do you destroy energy?

Energy at first impact is 1,088,910,000 joules, and after the BS of energy is decreased, the energy at next impact, despite the lost velocity is 2,184,800,192 joules; oops
The energy at second impact is twice as much as the first impact; now what?

Guess what, the collapse continues and get more energy each time mass is added, and the debris falls due to gravity.

What is your point? Is your point you take a superficial understanding of physics, cherry pick stuff that is correct, and ignore reality? Fail to do the work, and calculate what happens? Did you google this up, and not check it.

Tell me 5 percent lost velocity guru, how long does it take the debris front to make up the 5 percent lost velocity falling to the next floor, and the speed after impact was 7.86, and the next impact is in .4 seconds, and the speed is now 11.6 m/s, and the KE is now twice as much as it was at the last impact...

Tell me how the energy is lost, decreased... how do you destroy energy?

And remember, we don't need KE to destroy a floor in the WTC, all we have to do is overload it past 29,000,000 pounds, a kind of Catch 22 for the WTC structure... Good luck with 9/11 truth, the movement based on the ignorance of the followers, the true believers who come void of evidence, and a little knowledge of physics, or massive BS googled from failed 9/11 truth sources.
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Old 3rd April 2016, 01:14 PM   #162
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Originally Posted by kjr63 View Post
I don't understand what you are saying? You mean that when the upper block hits the lower floor and they get stuck together, the speed of the floor increases?
No. When the upper storey begins its collapse it's from a 0 mph start, like a sprinter waiting to start the race before the gun. If the same sprinter had a 1 mph rolling start s/he would have an advantage over the rest of the runners.

At the WTC the collapses didn't arrest after first (notional) impact, so the collapse then became more destructive than the original (notional) one-storey fall. Added mass from the newly detached floor joined in the game by falling along with the original mass.

An avalanche can start with a few rocks or a small patch of ice sliding away, right? By your reckoning, afaics, that small patch of sliding ice must be stopped after meeting a similar amount of ice. Tell that to villages that get wiped out by 10,000 tonnes of avalanche that started with just a few kg moving.
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Old 3rd April 2016, 01:18 PM   #163
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Originally Posted by Captain_Swoop View Post
How much speed?
We are right back where you started?
How much resistance did each floor offer?
I don't know. But it is counter-intuitive to think that there were not enough resistance to stop the collapse.

Do you know about this resistance?
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Old 3rd April 2016, 01:22 PM   #164
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Originally Posted by kjr63 View Post
I don't know. But it is counter-intuitive to think that there were not enough resistance to stop the collapse.

Do you know about this resistance?
I suspect this is because you think of the top and bottom as blocks. This was not the case.
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Old 3rd April 2016, 01:24 PM   #165
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Originally Posted by kjr63 View Post
I don't know. But it is counter-intuitive to think that there were not enough resistance to stop the collapse.

Do you know about this resistance?
lol, did you watch the video of WTC 1 and 2 when they collapsed?

There was not enough resistance to stop the collapse?, you ignore the fact energy is not lost; you failed to show your work.

Did you calculate the speed after impact?
Okay, take new mass and the new speed and solve E=1/2mv2

Go back Okay, take old mass and the impact speed and solve E=1/2mv2

How much energy was lost? lol

Do the work first and get back to us.

Next how do you resolve the fact a WTC floors fails above 29,000,000 pounds? What is the new mass after the first impact?
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Old 3rd April 2016, 01:30 PM   #166
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Originally Posted by kjr63 View Post
I don't understand what you are saying? You mean that when the upper block hits the lower floor and they get stuck together, the speed of the floor increases?
Let me try to explain what happens step by step:

Step 1: The collapse initiates - this means the entire mass above some level starts to descend as the result of all columns having failed. Conceptually, this large mass of falling material starts with a velocity of 0, or perhaps some low velocity, v0.
(You need to realize that, as all the columns have already failed, by definition, they are no longer supporting the falling mass - as a good first approximation, all of that falling structure is now, and will until the end, bypass the columns that are still standing)

Step 2: The falling mass falls freely (almost; air resistance and other friction are negligible) through 97% of the height of one story (full story height minus thickness of floor slab) and gains additional velocity, v+. This is equivalent to the mass gaining Kinetic Energy that is (almost) equal to the Potential Energy differential of the mass for 97% of story height.
Velocity is now v0+v+ - that's larger than v0

Step 3: The falling mass collides with the much smaller mass of the next floor slab below. This indeed slows the fall, probably with a deceleration that is several times g, but this deceleration only occurs along less than 3% of the story height; so even though deceleration is rather large, the velocity lost, v-, is less than the velocity gain v+ in Step 2. Since this collision is mostly inelastic, Kinetic Energy is indeed lost, mostly to concrete being crushed and steel being deformed, torn or sheared.
Velocity is now v1 = v0+v+-v- - that's still larger than v0, because v+>v-
Equivalently, the loss of KE is less than the gain of KE in Step 2.

Step 4: The falling mass falls (almost) freely through another 97% of the height of one story and again gains additional velocity, v+.
Velocity is now v1+v+ - that's larger than v1 (velocity after Step 3)

Step 5: The falling mass again collides with the much smaller mass of the next floor slab below. This again slows the fall, and again the velocity lost, v-, is less than the velocity gain v+ in Step 4. Again, Kinetic Energy is indeed lost to material deformation and heat.
Velocity is now v2 = v1+v+-v- - that's larger than v1, because v+>v-
Equivalently, the loss of KE is less than the gain of KE in Step 4.


You can now repeat Steps 4+5 all the way to the ground:
After each pair of steps, we have gained velocity, despite dissipating some of the KE.
In each Step 5, we are also adding some mass to the falling rubble.
Therefore, Kinetic Energy increases all the way down, because the gains in the fall phase (Step 4) are always greater than the losses in the collision phase.


This gives us a series like this:
v = 0 + (+15-3) + (+14 -2.8) + (+13.1-2.7) + (+12.2-2,6) + ...
The +- pairs in parentheses are v+ and v-, representing one story with one "fall"-Step and one "collision"-Step. The sum in each parenthesis is positive, and therefore, v increases from story to story to story.

Does this clear things up a bit for you?




(Note: In Steps 2 and 4 I used the same variable v+. This is not to suggest that in each repetition, the velocity gain is always the same. Similarly, the "v-" are not constant in each step 3/5.)
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Old 3rd April 2016, 01:40 PM   #167
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Originally Posted by kjr63 View Post
I don't know. But it is counter-intuitive to think that there were not enough resistance to stop the collapse.

Do you know about this resistance?
Stop posting until you get some help with physics...

http://www.physicsclassroom.com/mmed...ntum/trece.cfm

Take the time to think about a floor in the WTC fails above 29,000,000 pounds, and that the WTC shell and core held up the 110 WTC floors, a floor holds up itself.

Then BS about counter-intuitive, and explain to me how a floor can remain connected to the shell and core when the upper floors, which weigh more than what a floor can hold, will stop? Tell me how connections are able to not fail when overloaded with mass larger than a floor can hold is moving in a gravity field?

How is energy lost? that is not physics...
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Old 3rd April 2016, 01:48 PM   #168
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Originally Posted by beachnut View Post

How is energy lost? that is not physics...
There are too many comments, i answer just this.

I meant by that kinetic (mechanic) energy. That imo is the only energy here doing destructive work. Of course the energy is not lost, but transformed into some other form of energy.
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Old 3rd April 2016, 01:51 PM   #169
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Thing is the falling mass will always be too much for an individual floor to support so the floors will always fail.
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Old 3rd April 2016, 02:10 PM   #170
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Originally Posted by kjr63 View Post
I don't know. But it is counter-intuitive to think that there were not enough resistance to stop the collapse.
Granted - intuition is not always a sharp and precise tool, especially when dealing with magnitudes of masses and forces that you don't ever gain personal experience with.

That's why engineers and scientists use numbers and do math.

Originally Posted by kjr63 View Post
Do you know about this resistance?
The only significant structural resistance in the process we are looking at (the avalanche of material down the floor slabs, between the columns) is that provided by the truss seats - relatively small steel plates welded to the perimter columns and to girders on the core columns, upon which the floor trusses that hold the floor slabs are mounted.
When all the truss seats of one floor fail, the entire floor slab, and all that's sitting upon it, can and will fall down one story without meeting any significant further resistance.

NIST has determined that the truss seats of one floor have a combined static capacity of 29,000,000 pounds (see FAQ #12). In SI units (excuse me, I am from Europe ), that's 128,000,000 N.
If you apply that much force plus a little bit, the truss seats will "fail", i.e. they deform somehow, until they break, or shear, or tear - whatever failure mode fits. There is some flexibility, i.e. the steel can bend or stretch down some before it breaks, but not by far. Let's be generous and say that failure occurs after 4 inches (0.1 m) of deformation: By that time, the downward force has done an amount of work that is the product of force and distance. That's the energy dissipated (let me call this "DE") by the steel as it deforms inelastically:
DE = 0.1 m * 128,000,000 N = 12.8 MJ

Now, when the falling mass of, say, 12 floors falls through a height of 11'8" = 3.56 m, it converts Potential Energy (PE) into Kinetic Energy (KE). 12 floor slabs weighed very roughly 8,400,000 kg.
PE = m*g*h
= 8,400,000 kg * 9.805 m/s2 * 3.56 m
= 293.2 MJ

As you can see, the KE gained when the top started falling is 23 times the energy that the relevant structure, the truss seats, could dissipate before failing.
The first truss seat stood a snowball's chance in hell to stop the fall.

After the first floor below the collapse initiation level was thus punched out, 13 floors descended with greater velocity on the next floor slab - the chances of which were even worse.
And it got worse and worse as the collapse progressed!

As a matter of fact, much more energy was dissipated by the inelastic collisions, which simply shattered non-structural material - mostly concrete.
(And that, incidentally, explains why the concrete got so much shattered.)

So to answer your question "Do you know about this resistance?":
Yes. Short version is that the steel structure offered almost negligible resistance - only 1/23rd (ca. 4%) of what would have been required to stop the fall early on, and less than that in the later stages of collapse progression.
Most of the resistance was simple momentum transfer to floor slabs that got broken to small pieces in the process.





(For the pedants here: I am aware that it wasn't actually, literally 12 floor slabs impacting one floor slab at once; reality was a lot more complicated. My computation only offers the sorts of orders of magnitudes we are dealing with)
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Old 3rd April 2016, 02:53 PM   #171
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Originally Posted by kjr63 View Post
There are too many comments, i answer just this.

I meant by that kinetic (mechanic) energy. That imo is the only energy here doing destructive work. Of course the energy is not lost, but transformed into some other form of energy.
Wait, you said...
Originally Posted by kjr63 View Post
... If you increase mass 5% and lose speed 5%, energy decreases.
Now it is transformed...

Do you realize at the next impact the kinetic energy at the next floor is twice as much? How does this fit with the lost energy?

And? How can the collapse stop? Is that too many comments?

Show the math how the collapse can stop.

You said...
Originally Posted by kjr63 View Post
... If you increase mass 5% and lose speed 5%, energy decreases.
That is a lie, the energy remains the same.

... it only gets worse for 9/11 truth
http://www.physicsclassroom.com/mmed...ntum/trece.cfm

Originally Posted by kjr63 View Post
If a mass hits solid structure, it loses a lot of speed.
? really, 5 to 8 percent is a lot of speed?

Originally Posted by kjr63 View Post
... These floors cannot add anything to the destructive force. Each collision is a loss of kinetic energy.
The floors did add to the destructive force. How much kinetic energy is lost?

The speed, the velocity of the collapse matches what you get when you take the top mass, and add mass below, with the velocity lost at each floor, match a simple momentum model... and we get a 12 second or more collapse time.

It is funny, for 20 floors the speed decrease does seem to be 5 percent, but from the reduced speed, the new mass, 5 percent bigger begins to fall and accelerate... the next impact is twice the KE...
The amount of energy turned to heat and smashing wallboard, toilets, people, and concrete is not enough to slow the collapse, as seen on 911.
Do you have a point?
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Old 3rd April 2016, 03:17 PM   #172
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Originally Posted by kjr63 View Post
Yes, but minus the loss of speed when colliding with these all kind of structures below.
A car takes off from a full stop and accelerates. Keep the pedal to the metal and it accelerates steadily for, let's say 5 seconds.

Now do the same thing but every five feet it has to punch through a large paper barrier. The act of destroying the paper will take energy from that being used to accelerate the car. However the car never has its acceleration drop to zero.

There is a constant force on the car. Same with the falling mass. It is under a force due to gravity. It accelerates at initiation of collapse, encounters the next lower floor which will(in a simplistic approximation) act as an opposing force and reduce the downward acceleration. However unlesd it managed to reduce the acceleration to zero, it cannot, then that mass now begins its further drop from a non zero velocity whereas that first drop began with zero velocity.
At the next floor impact the velocity must now be hreater than at the previous impact. Thus greater energy at each level.
In addition, newly freed mass from each impact also falls and accelerates.
Increased mass, much of it at increased velocity.
Clear?
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Old 3rd April 2016, 04:37 PM   #173
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Originally Posted by JSanderO View Post
not stated properly... you can't increase energy... each released floor had stored potential energy... and that became kinetic energy... adding to that of the already dropping mass.
True the momentum increased, a sudden decrease at each floor unnoticeable, then an increase to the next.
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Old 3rd April 2016, 08:31 PM   #174
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Originally Posted by sts60 View Post
I'm not sure what good that would do. You've already, it seems, rejected a host of domain experts. Why would you lend credence to AZCat (<waves> how are things in Tucson?) no matter what gold-plated qualifications he/she brings to the table?

I see this sort of question asked occasionally by Apollo "hoax" believers, who seek to attack the claims of those maintaining the reality of Apollo by impeaching their domain expertise. They are almost invariably unqualified in the relevant fields themselves, however - as you appear to be - and have already dismissed the broad consensus among the community of actual experts.

So, here as in those cases, I am led to ask, what is the point of the question? What difference would it make to you whether AZCat's entire career was designing steel-framed highrises, or being assistant manager at a Baskin-Robbins?
Tucson's nice -thanks - but getting hot. Supposed to be near 100 deg. F mid-week.
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Old 3rd April 2016, 08:33 PM   #175
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Originally Posted by FalseFlag View Post
Explain how I have misrepresented structural design.
No. Do your own homework - the rest of us did. Why should there be special rules for you?
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Old 3rd April 2016, 08:45 PM   #176
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Originally Posted by FalseFlag View Post
Explain how I have misrepresented structural design.
Do you read your posts? Did you make your post?

Originally Posted by FalseFlag View Post
... Fact 1. Each floor, meaning the exterior and interior support columns, the trusses, the steel plates and the concrete slabs, were designed to support the current floor and everything above it. There was also a safety factor of 5x, meaning the building was designed to handle much more than the normal loads and stresses it would experience under normal conditions. ...
No, this is total BS...
"Each floor", meaning a floor, only supports itself with connections to the core and shell. The floor does not hold up anything but itself.
The floor will fail at loads above 29,000,000 pounds, about 12 floors in weight.
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Old 3rd April 2016, 08:54 PM   #177
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Originally Posted by JSanderO View Post
It appears that there is misunderstand about what NIST did and what their objective was. Accordingly what they published in their reports contains errors, is incomplete, are hypotheses explaining the collapses and is not intended to be proofs
Think about what you are saying. If their reports contain errors, or are incomplete, don't you think we need a new investigation?

Second, if they had access to massive amounts of information that the public will never see, what on earth makes you think the explanations given by "internet experts" are better than what NIST gave?

You, in your own words, have proven that there needs to be a real investigation into the collapses of WTC1, WTC2 and WTC7. At the very least, the new investigation needs to start with WTC7. Once we get the results, we can go from there.
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Old 3rd April 2016, 09:01 PM   #178
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Originally Posted by FalseFlag View Post
Think about what you are saying. If their reports contain errors, or are incomplete, don't you think we need a new investigation?

Second, if they had access to massive amounts of information that the public will never see, what on earth makes you think the explanations given by "internet experts" are better than what NIST gave?

You, in your own words, have proven that there needs to be a real investigation into the collapses of WTC1, WTC2 and WTC7. At the very least, the new investigation needs to start with WTC7. Once we get the results, we can go from there.
Fire did it, all rational engineers and engineering groups agree; less than 0.1 percent of all engineers claim a need for a new investigation. Less than 0.1 percent. lol, you have a fringe opinion... based on BS, when you need engineering and knowledge. You have opinion, based on nonsense, mocking the murder of thousands by 19 terrorists.

Don't worry, he can't list the errors, or list the incomplete part; he has opinions; you have the delusional fantasy of CD based on your opinions, and will never have evidence, math, or engineering to support your claims. There have been real investigations of the WTC complex; you must of missed the many independent studies and papers. Not surprised, you make up BS about the WTC, and are essentially off topic, having no clue what the topic is.
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Old 3rd April 2016, 10:18 PM   #179
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Originally Posted by beachnut View Post
all rational engineers and engineering groups agree
Prove this.
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Old 3rd April 2016, 10:29 PM   #180
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Deleted. No feeding.
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Old 3rd April 2016, 10:31 PM   #181
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Originally Posted by FalseFlag View Post
Prove this.
already done... the shallow, aka zero research exposed again.

Go to a library. You offer questions, no evidence, no valid claims.

When will you prove fire did not do it? never (ask questions, and answer them)
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Old 3rd April 2016, 10:39 PM   #182
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FalseFlag, I'd still like to hear your reply to my question in post 116. This is not a trick question.
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Old 4th April 2016, 01:44 AM   #183
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Originally Posted by FalseFlag View Post
Think about what you are saying. If their reports contain errors, or are incomplete, don't you think we need a new investigation?

Second, if they had access to massive amounts of information that the public will never see, what on earth makes you think the explanations given by "internet experts" are better than what NIST gave?

You, in your own words, have proven that there needs to be a real investigation into the collapses of WTC1, WTC2 and WTC7. At the very least, the new investigation needs to start with WTC7. Once we get the results, we can go from there.
I don't object to a new investigation. But it has to be for a good reason. I don't believe incriminating evidence has been withheld nor destroyed. My use of the term "mistakes" may be judgement calls, presumed assumption of fire behavior etc. and collapse hypothesis.

Essentially I believe there are other fire induced progressive collapse scenarios to consider... also speculative based on other assumptions which would lead to a similar outcome... total collapse.

I suspect that NIST make a "mistake" and down played the importance of the structural design as a driver of the collapse... and failed to stress that this building was quite unique in its design.

I would have liked to see the NIST fire assumptions used to model a similar sized building of more traditional design such as One Liberty Plaza from the same era... and see what the outcome is.

It appears that the lessons learned and applied are limited to:

emergency egress paths need to be more robust
fire suppression and fire protection systems need to be more robust
(codes need to reflect these)

I have not proven anything by my words. I expect official reports will always have a CYA aspect to them and rarely report civil or criminal charges be filed using the report findings as evidence.

I suspect this is what the truth movement expects from a new investigation... the uncovering of criminal wrong doing as insider conspiracy of some manner and an insider cover up of same.

My own speculation about 7wtc is that a tower should not have been built over a huge power station relying on massive load transfers and have tens of thousands of gallons of fuel stored on the site and in the building. I suspect the hubris (and greed in some cases) of developers, engineers, building officials and builders contributed to the decision to build over the power station.
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Old 4th April 2016, 08:49 AM   #184
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Originally Posted by jaydeehess View Post
A car takes off from a full stop and accelerates. Keep the pedal to the metal and it accelerates steadily for, let's say 5 seconds.

Now do the same thing but every five feet it has to punch through a large paper barrier. The act of destroying the paper will take energy from that being used to accelerate the car. However the car never has its acceleration drop to zero.
That is a wrong analogy. Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
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Old 4th April 2016, 08:53 AM   #185
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Originally Posted by sts60 View Post
So, here as in those cases, I am led to ask, what is the point of the question? What difference would it make to you whether AZCat's entire career was designing steel-framed highrises, or being assistant manager at a Baskin-Robbins?
If he was assistant manager at a Baskin-Robbins I would consider him an authority on ice cream. I might ask him for suggestions on a good flavor, but I would not consider him an expert on engineering topics.

If he was an engineer, I would consider him an authority on topics related to engineering. I might ask him for his opinions on engineering topics. If he gave his opinion, and it clearly contradicted basic physics and the opinions of other engineers, I would still consider him an authority but his opinions would have no credibility. I would not ask him for future opinions. I would also consider his presence on a forum such as this highly suspect.

To beat you to your next post - I already said I am not an expert. You should not consider me an authority on engineering issues. What you should do is pay attention to credible engineers, and use your own judgement and understanding of basic physics to know who is right.

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Old 4th April 2016, 09:08 AM   #186
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Originally Posted by kjr63 View Post
That is a wrong analogy.
Why did you not address my analogy? I believe it is a correct analogy.

Originally Posted by kjr63 View Post
Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
Are you saying the first floor to collapse was 20 times higher than all others below? That would be wrong by a factor of 20
So your analogy is wrong, too. You should have equidistant walls - all 100 feet apart.

If the car can break through the brick wall after acceleration from 0 for 100 feet, AND it has some velocity left, then anothe 100 feet later, it will be faster than it was just before the first wall (because this time it got a running start), and will punch through the second wall more easily, retaining more velocity, and so on. Wall after wall after wall, that car will be faster than it was punching through the wall before.
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Old 4th April 2016, 09:23 AM   #187
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Originally Posted by kjr63 View Post
That is a wrong analogy.
Every analogy is wrong to some degree. Some are less wrong than others.

Originally Posted by kjr63 View Post
Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
This is known as "pulling numbers out of thin air" (in the more polite form). Why do you arbitrarily choose the numbers you've chosen, and most obviously, why have you chosen to have a much greater distance for the first period of acceleration than all the subsequent ones?

Try modifying your analogy slightly. Suppose the car has thirteen feet in which to accelerate, at which point it hits the first wall, and that the wall is weak enough that the car breaks through it without coming to a stop. It then has another thirteen feet to accelerate, after which it hits another wall. It's going faster this time, because the second thirteen feet of acceleration wasn't from a standing start, so if it slows down the same amount it'll be going faster than it was after hitting the first wall. It should be fairly obvious that, as long as the car gets to accelerate between walls, no number of walls will stop it; it will be going faster and faster after every collision.

Now, which of these analogies is less wrong when applied to a building where the spacing between floors is constant? Yours, where the first spacing is arbitrarily chosen to be twenty times all the others? Or mine, where they're all equal?

That's a rhetorical question, by the way.

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Old 4th April 2016, 09:30 AM   #188
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Also imagine that the bricks from the first wall are moving with the car adding to its mass when it hits the next wall and so on.
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Old 4th April 2016, 09:43 AM   #189
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Originally Posted by kjr63 View Post
That is a wrong analogy. Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
Your analogy goes way too far in the strength of the barrier, mine is way too far in the other direction.

You can see by my analogy that in changing the strength of the barrier, the effect on acceleration can be negligible. In fact unless that barrier is such that it reduces acceleration to ZERO, the vehicle will be accelerating from having gone through each barrier, with an initial non-zero velocity.

v=v0+0.5at
The first acceleration starts with v0=0, next acceleration past first barrier v0>0

"a" only changes during the time the barrier is being destroyed, which is pretty momentarily. After that, between barriers, acceleration is the same as it was initially.

You seem to be having difficulty recognizing the difference between acceleration and velocity and how they are related here.

At each barrier the velocity after destruction of that barrier need not be less than initial impact velocity. It CAN and, in the case of the WTC towers does, accelerate through it. Its that acceleration that is less than at initial impact, slightly less in the case of the towers. (As Oystein points out ~1/23 reduction, since force is directly proportional to acceleration)

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Old 4th April 2016, 09:51 AM   #190
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Originally Posted by kjr63 View Post
That is a wrong analogy. Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
The car is not subject to the force of gravity.

Gravity. It's the law!
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Old 4th April 2016, 09:58 AM   #191
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Originally Posted by kjr63 View Post
That is a wrong analogy. Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
For reasons that others have mentioned this is not a suitable analogy. I'm beginning to think that you're not sincere about wanting to debate this issue in a rational manner.
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Old 4th April 2016, 10:15 AM   #192
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Originally Posted by kjr63 View Post
That is a wrong analogy. Imagine a some sort of brick wall that the car cannot punch through without kinetic energy, like a building can carry all the potential energy when it's standing.

Then let the car accelerate with full force 100 feet before hitting the first wall. It punches through, but loses most of it's speed. It accelerates then 5 feet distance, but cannot punch through many more because it is continiously losing speed, and 5 feet acceleration is not enough to punch through.
First off, your car most likely does not accelerate at g, a Porsche 911 Carrera S can hit .67 g, there are some which can. We need $$$100,000 or more to do this... the bricks, or what ever mass you hit would then accelerate at the new speed of the car and the bricks based on momentum transfer, and this new mass would continue to accelerate at g...
A car is a bad example, it is not falling. When a car hits something, does the something including stuff ejected then follow the car at g? The WTC is up, and it is falling down, and the earth is driving the collapse at g, and we observe the velocity over time based on momentum transfer.

The WTC is falling down, the acceleration of all the mass is at g.

The WTC falling, when a lower floor fails, the speed is only decreased by the momentum exchange. The data for the fall of the WTC shows it matches the rate of fall of a momentum model. Lost velocity for the first impact; You said 5 percent, not most? Is 5 percent most?

The WTC collapse slowed 5 percent at the first impact going about 7 m/s, but at the next floor the speed was over 10 m/s. Do the math, not what you think will happen, what happens based on physics, not BS. The kinetic energy of the mass at the second impact is twice the kinetic energy of the first impact due to distance falling in a gravity field; the new velocity, and 5 percent more mass.

In addition, the WTC floors fail when overloaded. The floors can hold 29,000,000 pounds based on the connections to the shell and core, and fail above that. A WTC floor overloaded fails; add up the upper sections; on 911 the top sections falling were more than 29,000,000 pounds.
Thus a car analogy is not very good, does the brick wall fail when the car touches the brick wall? In the WTC if the upper section touches, sits on the lower floor, the floor fails instantly; does the brick wall? Plus would bricks hit then go forward with the car at the acceleration of g... in the WTC floors which fail push on the accelerator and accelerate at G like a $350,000 dollar super car... can the brick wall do that?

The WTC falling is like a super car accelerating, for free, due to gravity. If we want our stock cars to be some of the fastest cars in the world, drop them from great heights.
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Old 4th April 2016, 10:22 AM   #193
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Originally Posted by FalseFlag View Post
If he was assistant manager at a Baskin-Robbins I would consider him an authority on ice cream. I might ask him for suggestions on a good flavor, but I would not consider him an expert on engineering topics....
To avoid splitting the topic across two threads, my reply to FalseFlag is over in the "If it doesn't agree..." thread.
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Old 4th April 2016, 11:06 AM   #194
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Originally Posted by NoahFence View Post
The car is not subject to the force of gravity.

Gravity. It's the law!
My analogy was a car that is accelerating. The engine is the supplier of a constant force.

Its a valid analogy. The only difference is that the force is horizontal and the barriers vertical.

Last edited by jaydeehess; 4th April 2016 at 11:07 AM.
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Old 4th April 2016, 11:43 AM   #195
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Originally Posted by jaydeehess View Post
My analogy was a car that is accelerating. The engine is the supplier of a constant force.

Its a valid analogy. The only difference is that the force is horizontal and the barriers vertical.
Yep, it was a fair enough analogy until kjr63 decided to arbitrarily change the spacing of periods of acceleration/collisions
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Old 4th April 2016, 11:54 AM   #196
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Originally Posted by Oystein View Post
(You need to realize that, as all the columns have already failed, by definition, they are no longer supporting the falling mass
What caused all of the columns to fail simultaneously?
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Old 4th April 2016, 11:58 AM   #197
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Originally Posted by pgimeno View Post
Incorrect. The floor-to-column connections are very feeble in comparison to the column strength
If the floor to column connections failed first, then what caused the columns to fail? Remember, the pancake collapse theory was abandoned, so whatever wizardry and nonsense you use for your explanation better not have one floor falling on another.
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Old 4th April 2016, 11:59 AM   #198
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Originally Posted by jaydeehess View Post
My analogy was a car that is accelerating. The engine is the supplier of a constant force.

Its a valid analogy. The only difference is that the force is horizontal and the barriers vertical.
I was showing kjr that his analogy is flawed. He's missing gravity in his analogy with cars running through walls.
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Old 4th April 2016, 12:04 PM   #199
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Originally Posted by FalseFlag View Post
If the floor to column connections failed first, then what caused the columns to fail? Remember, the pancake collapse theory was abandoned, so whatever wizardry and nonsense you use for your explanation better not have one floor falling on another.
You refer to the ones that still existed after the aircraft struck the building?

Fire made them fail first, then the weight of the building did.

I had a gut feeling they were coming down before they even did. Am I in on it?

I based my feeling on the pretty well established common knowledge that steel doesn't fare well in fire. Especially one of that ferocity. I also suspected (since confirmed) that there were no efforts to fight the fire. What's taking you so long?
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Old 4th April 2016, 12:06 PM   #200
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Originally Posted by pgimeno View Post
Can't you see the dust ejections from the falling floors as they break the connections to the columns? The columns clearly stand while the floors fail.
Yes, some columns are standing while the floors are pulverized and ejected laterally. You should really stop saying that they fall. It makes people assume that everything came straight down. That is not what happened.

I also see pulverized building contents being generated and ejected laterally at a near constant rate. Do you see that too?

In your picture, I see pulverized contents being laterally ejected to the right. In fact, the pulverized contents are being laterally ejected at nearly the same rate and with nearly the same force that it appears there is another mass falling at the same rate at an equal distance from the footprint of the tower? Do you see that, too? That column of dust on the right that seems to have a consistent width? I wonder how the collapse could be so symmetrical, and the forces so constant.

I also wonder what the laws of physics tell us when something continues to accelerate as it falls. What do the laws of physics say about this? Something about apparent weight. Hmmm. Could that be a clue? If something is accelerating, what is it's apparent weight? Is it more or less than its static weight? Hmmm. Could the answers to these questions be clues?

Nah. Nothing to see here.
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