|
Welcome to the International Skeptics Forum, where we discuss skepticism, critical thinking, the paranormal and science in a friendly but lively way. You are currently viewing the forum as a guest, which means you are missing out on discussing matters that are of interest to you. Please consider registering so you can gain full use of the forum features and interact with other Members. Registration is simple, fast and free! Click here to register today. |
2nd June 2016, 02:00 PM | #1 | ||
Scholar
Join Date: Dec 2015
Posts: 97
|
Failed Truther Paper Fall Time Analysis.
Posted below is a "paper" by truther Marty Beck. I'll just leave this here.
https://lookaside.fbsbx.com/file/WTC...8LAiwOQVf_eitg Marty Beck, 4/20/2011 Analysis of the Fall Times of the Three World Trade Center Buildings Abstract: Explaining the collapse of the three World Trade Center buildings has been an enigma that strains the mind to come to grips with. Those who look at it over and over again try to make sense of what they see. The recorded fall times somehow seem reasonable to many of us when we rely on intuition in thinking about the collapse. Many citizens are reasoning much like Galileo’s contemporaries must have. They easily assumed a heavier ball falls faster than a lighter ball. Until the experiment. We assume a large mass unleashed could fall at the rate we see. Before Galileo’s experiment they must have wondered why anyone would bother to do the experiment; isn’t it obvious?
|
||
2nd June 2016, 02:10 PM | #2 |
Loggerheaded, earth-vexing fustilarian
Join Date: Sep 2006
Location: Wales
Posts: 31,398
|
This part is especially hilarious:
"Weight is the result of mass in earth’s gravity field and the weight pushing down is the force defined as F=ma where m is the mass of the 33 stories and a is the acceleration due to gravity. On earth a is 32 ft/sec2. So before the collapse was initiated, the weight was 80 million pounds. Once the upper 33 floors start to accelerate at 20 ft/sec2, the resulting force is now proportional to the difference between the 32 ft/sec2 and the 20 ft/sec2. This is 12 ft/sec2 with a resulting force of only 12/32 of what it was before the collapse. " Thus a falling mass, at impact, exerts less force than it would have done at rest. Uhuh, uhuh. I must experiment tomorrow with stationary bricks on my head vs. falling ones. Or maybe drop some Truthers off a balcony. |
__________________
"There ain't half been some clever bastards" - Ian Dury |
|
2nd June 2016, 02:20 PM | #3 |
Illuminator
Join Date: Feb 2009
Location: Spain
Posts: 3,692
|
|
2nd June 2016, 02:41 PM | #4 |
Guest
Join Date: Nov 2010
Posts: 12,673
|
Quote:
I don't trust that number. I bet I could find out before RocketBoy2.0 gets his cast replaced. Go! |
2nd June 2016, 02:44 PM | #5 |
Scholar
Join Date: Dec 2015
Posts: 97
|
|
2nd June 2016, 03:05 PM | #6 |
Guest
Join Date: Nov 2010
Posts: 12,673
|
http://www.structuremag.org/?p=1163
This random source said 110 to 115. I would check every single datapoint in the paper based on this information. |
2nd June 2016, 04:08 PM | #7 |
Skeptic not Atheist
Join Date: May 2007
Location: West of Northshore MA
Posts: 24,748
|
|
__________________
"Remember that the goal of conspiracy rhetoric is to bog down the discussion, not to make progress toward a solution" Jay Windley "How many leaves on the seventh branch of the fourth tree?" is meaningless when you are in the wrong forest: ozeco41 |
|
2nd June 2016, 06:06 PM | #8 |
Illuminator
Join Date: Oct 2006
Posts: 3,454
|
No, this guys calculation about this is correct, with a clarification. WHILE the upper mass is descending at an approximately constant 20 ft/sec^2, it is pushing down on the lower mass with a force equal to 12/32s of its weight. A Force diagram shows this. There are two forces acting on the upper mass (m): Fgravity (pulling downward at mg = m 32.2 ft/sec2 = the upper block's weight. A resisting force pushing upward from the lower mass. We don't automatically know the magnitude of this force, but we can calculate it easily. Fresultant = fgravity - fresisting The gravity force (aka, "weight) and the resultant force are positive because they are downward. The resisting force is negative, because it is upwards. We know that the RESULTANT downward acceleration is 20 m/sec2. Therefore the resultant force acting on this body must be the mass of the body times its resultant acceleration. Fresultant = m aresultant. Equating the two resultant forces, and rearranging the terms gives: fresisting = fgravity - Fresultant fresisting = fgravity - m aresultant fresisting = m g - m aresultant fresisting = m (g - aresultant) The resisting force upward is equal to the mass times (g - a). In this case, fresisting = m (32 - 20) = 12 m/sec2 m Kg __ By Newton's 2nd law, the force that the lower block exerts on the upper is exactly equal to the force the upper body exerts on the lower one ... again, WHILE it is falling at this acceleration. As counter-intuitive as it may seem, YES, while it is falling, it is exerting LESS force on the lower body than when it was stationary. The loads on the lower floors' columns dropped, decreased in magnitude, while the building was collapsing. The lower body can not stop it because of load path & the destruction to the topmost floor before the upper mass even arrives at that floor. __ Later in the fall, the resistance likely rose to equal the (increasing) weight of the upper block, and then it likely reached an equilibrium: terminal velocity. Two factors caused it to reach terminal velocity: 1) as it picked up speed, it was hitting more floors per second, and it had to force the air out of the room space faster & faster. __ In any impact, the full momentum / kinetic energy of the falling block can be turned into an enormous force, capable of fracturing the components trying to stop its fall. In this case, the force that the falling body could exert on some resisting member could have risen to many, many times its own weight, depending on how fast the structure tries to bring the upper block to a halt. __ Scanning over the intro, there seems no need to read the rest of it. Anybody have any idea what this guy's credentials are? |
2nd June 2016, 08:54 PM | #9 |
Bandaged ice that stampedes inexpensively through a scribbled morning waving necessary ankles
Join Date: Jan 2007
Location: Cair Paravel, according to XKCD
Posts: 34,249
|
The paper, so far as I can see, is based entirely on the simple, but colossal, error of assuming that the structural strength of a collapsing column remains constant throughout its collapse. I realise that there are people insufficiently intelligent to appreciate that this is not the case, but I don't think there's much to be done for them above and beyond meeting their immediate care needs.
Dave |
__________________
There is truth and there are lies. - President Joseph R. Biden, January 20th, 2021 |
|
2nd June 2016, 09:11 PM | #10 |
Penultimate Amazing
Join Date: Nov 2006
Location: 40 miles north of the border
Posts: 20,849
|
Quote:
With mass falling and destroying floors and truss connections, most of the dynamic forces generated simply bypass the columns. |
3rd June 2016, 04:41 AM | #11 |
Scholar
Join Date: Dec 2015
Posts: 97
|
|
Thread Tools | |
|
|