[boloboffin]

David Chandler does it agin!

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I AGREE

This one was posted April of last year, so maybe somebody's already jumped on it, but this is a SPECTACULARLY BAD mistake on his part.

He claims that a piece of structural steel traveling horizontally at 32 m/s from the collapse can't have been a ricochet from the collapse, because by the time the descending section reached it, it only would have been travelling at 16 m/s. You might think conservation of momentum, big piece, little piece, but, oh, no. It's worse than that.

For the sake of the argument, I'm accepting his figures. The leading edge of the descending section is the 96th floor and the piece breaking off is at the 82nd floor. That means, with a floor height of 4.06 m, that the leading edge must descend at least 13 floors, or 52.78 m before breaking off the ejected debris.

Chandler claims that it's only going 16 m/s, but he couldn't be more wrong.

http://www.ajdesigner.com/constantac...avelocityt.php

Solving for time, you plug in initial velocity (0), final velocity (16), and acceleration (9.81). You get 1.63 seconds.

http://www.ajdesigner.com/constantac...vevelocity.php

Solving for average velocity, you plug in initial velocity (0) and final velocity (16). You get 8 m/s.

http://www.ajdesigner.com/constantac...splacement.php

Solving for distance, you plug in time (1.63) and average velocity (8 m/s). You get 13.04 m.

So in freefall conditions, as specified by Chandler, if the final velocity is 16 m/s, the descending section has only fallen 13.04 m, not 52.78 m.

Chandler screwed up big time. As a matter of fact, after falling 52.78 m at 9.81 m/s2, you get a final velocity of 32 m/s, exactly the velocity of the horizontal component as measured by Chandler. Assuming a final velocity of 32 m/s --

http://www.ajdesigner.com/constantac...avelocityt.php

Solving for time, you plug in initial velocity (0), final velocity (32), and acceleration (9.81). You get 3.2 seconds.

Average velocity is 16 m/s.

http://www.ajdesigner.com/constantac...splacement.php

Solving for distance, you plug in time (3.2) and average velocity (16 m/s). You get 51.02 m, much closer to the actual distance than Chandler. Using the assumption that the upper section is descending with no resistance, it CANNOT physically have fallen 52 m faster than 3.2 seconds, and by that time it will be traveling around 32 m/s.

Oh, my, how Chandler did screw up. Is it just a coincidence that the actual average velocity is what he claims the final velocity to be? Did Chandler grab the average velocity and use it as final velocity and post a big screw up on the intertubes? Does he ever get tired of confirming the "official story"?

Somehow, this must be NIST's fault, right?