I'm not going through all this but sqrt(2d/g) with d = 110 * 3.8m and g = 6.81m/s^-1 gives a time of 11.4s. With d = 95*3.8m it gives 10.7s. I don't know where 10.6s comes from.

To be a little more clear:

The system is accelerating as a whole due to the resultant force which is the weight minus the normal reaction.

The pile driving upper 12 floors block and its target do indeed act on different objects. Let A = pile driver on target. Let B = target on pile driver. A acts on B and B acts on A, with forces equal in magnitude and opposite in direction as per newtons 3rd law. No relative acceleration is caused here, i.e. the block and target are coupled together and hence acclerate at the same rate. The force of the pile driver on the target is therefore 0.36mg.

"Why would the pile driver upper block exert a force smaller than its static weight and accelerate?" Is the right question. It is the question Chandler is asking.

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Rounding error.

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Oops multiple new posts without addressing the multiple issues with your theory and why you disagree with the video evidence of collapse times much longer than 12 seconds.

Surely it was just your 56th oversight in a row and you are not just a complete wimp.

Ok I mean I'd need to spend more time than I want to to fully understand this. But if his model says the building should collapse in under 11 seconds, and we see with our own eyes that it takes 15 seconds or longer, then the model is clearly wrong. I mean, don't get me wrong, it might still be correct for some things, just not for collapse time. Unless he or you can address why the model does not reconcile with what we can see in reality.

"All models are wrong. Some are useful." - some guy whose name I forget.

There's a guy ITT who's a pro at rounding measurements, you should go see him about that. Oh, wait.

Why does it take dozens of times of repeating the same thing to get it into your thick head Billy? First we had it with the exterior panels, now we have the same pattern emerging with the model collapse times disagreeing with what we see in reality.

And just to be clear, this isn't us looking at a pile of rubble and saying "well it doesn't look like 1.8m tonnes". This is an event where you can pause the video and see for yourself that at the time the model claims the event has completed, it has not completed, and in fact goes on for at least another 4 seconds. There is little room for subjectivity. Unless someone can provide a persuasive explanation why the model is correct and this basic objective analysis is wrong, which nobody has even attempted to do.

Here is a thread with responses to some of Chandler's claims:

https://www.metabunk.org/threads/und...-3-of-g.12525/

Billy used to tell us over and over again that we should trust what we actually SEE!

He used to emphasize that principle while posting his pics.

Now he no longer posts pics, and we're supposed to believe models instead of what we see with our own eyes.

I'm very confused!!! (To be fair, I'm very easily confused.)

I think what Flatty is claiming is that the buildings felll at speeds faster than freefall and that would be impossible if the building collapsed only under its own weight. It would seem he believes the forces in the opposite direction would also “slow down” the collapse and that another source of force must be present, such as controlled demolition, to explain the collapse at the speed of near freefall. Or space lasers.

But since he never answers questions or says anything sensical, this is just a guess.

He doesn't believe they fell at all. He believes they got dustified by space lasers. So he's been trying to prove that they can't have fallen, because they "collapsed" faster than the laws of physics would allow. The only problem is that it is complete and utter horseshit, because he claims they collapsed in 12 seconds or less (NIST and other sources have in fact given figures that comport with this claim, but these figures are clearly incorrect), but video of the event unequivocally shows it was 15 seconds or more. He is debunking a strawman, essentially.

Actual engineers and qualified experts that have discussed Chandler's paper are not kind, for the record.

https://internationalskeptics.com/fo...llapse.168450/

Chandler does make some pretty basic errors (eg not differentiating between a static and dynamic load), so it's not surprising. I can see why billy likes him.

Yeah, according to this thread, looks like the part I intuitively found suspect is in fact total horseshit.

Sarcasm from this poster, obvs, but this is also the part I could not reconcile in my mind. I was afraid it was because I was missing some basic principle of mechanics. Looks like I wasn't.

This poster also summarises it quite well:

I now have a definitive calc for the collapse time based solely on available, irrefutable data.

1. Calculating the total height of the fall.

95% of the world trade centre was air, i.e. 5% solid material. 5% by volume gives 13.57% by area. The frontal surface area is therefore expected to squash down into a surface area of height 13.57% of the total height. 110 floors therefore collapse down to a height of

13.57% x 110 floors = 14.9 floors. Let us say 15 floors.

The upper 12 floor "pile driver", i.e. floors above the 98th floor combined as a single mass, fall through a height of

98 - 15 floors = 83 floors

before being impeded by the crushed mass beneath it.

Total tower height = 417 m.

417 m / 110 floors = 3.79 m/floor.

83 floors have a height

83 x 3.79 m = 314.57 m.

This is the height of the collapse.

2. Calculating the rate of acceleration.

Referring to extensive video analysis of the initial 4 seconds of collapse (see Chandler above) the acceleration is a uniform 6.31 m/s2.

3. Time, t

= sqrt(2s/a)

= 10 s (2 sf).

Consistent with times stated by NIST, Eagar and Bazant.

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More wrong than right in this post.

I will not bother to correct since you did not bother to be accurate.

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Chandler was trying to expose the contradiction himself. Wasn't amazingly presented but with perseverence we see his point.

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Link does not work for me.

And i really want to know what the international wankers think. I mean skeptics.

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It's like magic how it works for everyone else.

The who? These are qualified experts in the relevant field. Show a little respect, dickface

Excellent. Now can you explain why your calculation contradicts footage of the event? After 11 seconds we can clearly see a significant portion of the building remaining, much more than 15 floors.

Thought we were listening to experts now, Billy? Or let me guess, we only listen to them when what they have to say supports your conclusion.

You also did not get a few basics from me, which were clear enough.

I would not ordinarily point score on these things, because it is tricky and can be counter intuitive (btw watch Walter Lewin's mechanics lectures on loltubz, they're fantastic) but if you are going to throw mud at Chandler you will get what is coming. Because he is in fact correct.

All an aside ofc, the info I present from Chandler is the acceleration gives the correct collapse time and supports the growing list of expert analysis of the time being around 10 s.

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Whatever he was trying to expose, his argument seems to be predicated on the principle that an accelerating mass exerts less force than it does when it is static, which, as I suspected, is crazy talk.

On the contrary I need an update from them re the latest jokes about disabled people.

Seriously though give me a link that works.

Also a forum is not a properly authored paper. You see there is no accountability. Might as well cite reddit. Or 2p2.

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I'm not qualified to comment the mechanical principles he espouses, but they seem wrong, and I find the arguments that they are in fact wrong more persuasive than his arguments. But again, this has little to do with the timing issue.