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Collapse vs. Demolition

9/11 Experiments: Collapse vs. Demolition ~ Part 1 of 2:

http://www.youtube.com/watch?v=ww8hBFNY8jk

 

9/11 Experiments: Collapse vs. Demolition ~ Part 2 of 2:

http://www.youtube.com/watch?v=dgZLXI3whGA

Excellent work

You've applied various criticisms of your already well done previous effort to great effect. I'll be referring people to these new videos constantly.

Construction integrity.

I often think people need to understand how sturdy a hirise building is built, considering the strict regulations regarding people safety, not to mention the risk of lawsuits in the event of accidents.
Even with my elementary knowledge of architecture and building design, I knew instinctively that there's no way in a million years that the 3 buildings could collapse through the path of greatest resistance. And yet they all did. Like they were constructed of popsickle sticks.
I imagine it in terms of taking a stack of concrete blocks cemented together and knocking out half the 9th block with a sledge hammer. The top blocks may topple over but the bottom blocks would stand firm. Maybe a stack of blocks is not comparable in relative terms to a hirise but it works for me.
I just wish I had the expertise to explain that in terms that are easy to understand to people who have no concept of engineering or physics.
Any experts out there?

The Mob

"Galileo wrote to Kepler wishing they could have a good laugh together at the stupidity of 'the mob.'; the rest of his letter makes it plain that 'the mob' consisted of professors of philosophy, who tried to conjure away Jupiter's moons, using 'logic-chopping arguments as though they were magical incantations.'"
Bertrand Russell, A History of Western Philosophy

In our day, the "mob" consists of skeptics, debunkers, Bush crazies, the mainstream media etc. who attempt to conjure away free-fall, Newton's third law, and physical evidence with the same 'logic-chopping arguments'(i.e. Ockham's Razor). Have we made any progress in the last 400 years?

bravo

good work- i can see the links now!
i appreciate the simple logic of your presentations
i majored in math at birmingham uni, uk a long time ago... and i appreciate basic physics as we studied some of that under the coursename- applied maths
Douglas

Absolutely Superb

Jon,

Well organized and edited. Important points explained in simple terms.

Among the best videos on the subject.

Thank you very much.

Interesting footage

I stumbled across this montage this morning and post it here for reference. There's no sound (except at the end, Dan Rather commenting on WTC7). Whoever made this vid did a great job of side-by-side comparisons of CD's and WTC destruction.

@ Jon:
Great job on the re-edit. With a little more rearranging and a few more tweaks, I'm sure you could combine Parts 1 & 2 and get it all in one clip that comes in just under 10 minutes.

Great job Jon! We make these

Great job Jon!

We make these videos sometimes for a captive audience, with that in mind, can you, on your next video, say a little more about your background and experience? That would help first timers or relative newcomers.

Keep up the excellent work. Illustrative videos are vital to understanding the physics of the collapses.

John

The baseball bat comparison

The baseball bat comparison is a poor one that will actually work against you. Here's why. You have two events. One that is reproducible and one which is not reproducible. Both of them should show de-acceleration (the WTC collapse when the top section impacts the intact bottom section& the bat when it strikes the ball) You admit that to the naked eye neither shows obvious de acceleration. You also admit that in videos shot at 'normal' speed (frame rate about 24 frames per second..coming from a Super 8 movie background) that no de-acceleration is obvious. But here's the kicker,in order to show that the bat did in fact de-accelerate you had to use video shot at a much greater frame rate (frames per second/'slow motion'). that is a de-facto admission that it is possible that the WTC collapse could have shown de-acceleration but the video you studied simply didn't have sufficient information within it to show it!
What was the frame rate of the video you analysed to determine there was no de-acceleration? Can you prove that a baseball bat de-accelerates when a ball is struck using only video shot at the same frame rate?That's the sort of question you could expect from the JREF crowd,can you answer them?

Well, the bat analogy is confusing anyway

The bat is much heavier than the ball, so it won't be decelerating much when it transfers momentum to the ball.

And the bat is only moving a few feet, but it is moving very rapidly, having been accelerated by the batter, whereas the WTC would increase its velocity in one second of freefall due to gravity by 32 ft per second, which is relatively slow compared to the bat.

Video frame rates are typically about 30 frames per second. This would be plenty enough time to see a jolt, if there was one, when the first collision occurs between floors because it should occur after about 1 second of falling, at which time the freefalling top section would be moving with a velocity of 32 feet per second, so one frame (at 1/30 of a second per frame) would correspond to about 1 foot of motion.

Now the resolution of the Sauret video, which is one of the best to use for timing the initial few seconds of the WTC1 "collapse", allows us to sample the position of the tower at about 0.88 feet per pixel. (See http://www.journalof911studies.com/volume/2008/TheMissingJolt7.pdf)

So if the decrease in velocity due to the first impact between floors is as little as 1/30 (or 3.33%) of the velocity after one second (which, again, would be 32 feet per second if it were freefalling), that should result in a measurable loss of one pixel. That is if we are looking at every frame.

But, in fact, the actual velocity after one second is not 32 feet per second but 21 feet per second, as calculated from the rate of change of the measured position. Then we can calculate the acceleration from the rate of change in the velocity, and it is a very constant 64% of gravity over the first 3 seconds. See the blog transcript of Chandler's http://911speakout.blogspot.com/2010/05/downward-acceleration-of-north-tower.html. The problem is not that is that so low, but that it is so high, so close to freefall, and furthermore, that the acceleration is so constant (at 64% of gravity), and not decreasing enough over 3 seconds as it should with each subsequent impact.

The counter-argument for why we don't see a jolt after one second is because it is spread out over time due to the tilting of the top of the tower. so the impact of parts of the floors does not occur all at once. This might explain the lack of a visible jolt, but it doesn't explain the lack of appreciable deceleration.

The *constant* acceleration during the first 3 seconds means there is a constant resistance force (by the lower part of the tower) of only 36% of the weight of the top section that it used to support. And actually, it used to be able to support at least 3 times that weight, so the observed resistance is only about 1/9th of its original strength. How did the tower structure suddenly and uniformly lose 8/9ths of its strength for 3 seconds?