Open Letter to Dave Thomas

[carlitos]

Perhaps the bombs and blasting mats both were made of unobtanium.

How could a 'blasting mat' be applied to an exterior column in an office building full of windows, Mr. super-physics guy?

 

[cmatrix]

That's a misrepresentation of what Dave Rogers wrote. From what we have seen so far, it is entirely possible that cmatrix does not understand that converting some of the available GPE to kinetic is not the same as converting all of it.


cmatrix is still having trouble with that Lagrangian.

The problem is not with me. I understand that converting some of the available GPE to kinetic energy means the object will not be in free fall.

 

[DGM]

If WTC 7 was CD it would have had to have been setup at least two weeks before. Blasting mats are a technology used to dampen the sound and collateral damage caused by explosives. Who's to say the perpetrators didn't have access to some sort of new lightweight blasting mat technology.

I love it when you guys have to make-up new technology so you can fit your "theory" into reality.

Good job!

 

[carlitos]

Perpetrators is deliciously sinister and vague. I love a plot with an unnamed protagonist.

 

[BigAl]

If WTC 7 was CD it would have had to have been setup at least two weeks before. Blasting mats are a technology used to dampen the sound and collateral damage caused by explosives.

You've never seen a blasting mat, have you?

 

[cmatrix]

Er,no. That's what's called in the trade a 'strawman argument'.

A CD could cause a period of freefall if it were carefully engineered to do so. In practice it doesn't because there's no need to go to such lengths.

The 8-storey 'freefall' at WTC7 is - if you step back, stay calm and really think about it - powerful evidence against CD.

No. Free fall means CD. That is an ordinary claim. The extraordinary claim is that free fall could result from something other than CD. For real skeptics extraordinary claims require extraordinary truth. Crackpots only need faith.

 

[Sword_Of_Truth]

If WTC 7 was CD it would have had to have been setup at least two weeks before. Blasting mats are a technology used to dampen the sound and collateral damage caused by explosives.

Oh good lord...

 

[cmatrix]

I believe the NIST story based on a knowledge of how steel behaves under fire conditions and the vast evidence of massive fires throughout WTC7.

Then you should be easily able to produce the "knowledge" that shows fire can cause 8 stories of structure to be completely removed to allow free fall for 2.25 seconds.

 

[DGM]

The problem is not with me. I understand that converting some of the available GPE to kinetic energy means the object will not be in free fall.

Let's say you drop a 1 Lb. weight from 1" and 1' or even 10'. They all fall at "free-fall". Which would you rather your foot be under (If you had to make that choice)

 

[excaza]

The problem is not with me. I understand that converting some of the available GPE to kinetic energy means the object will not be in free fall.

GPE and KE have absolutely nothing to do with free fall. You've been told this repeatedly.

 

[cmatrix]

GPE and KE have absolutely nothing to do with free fall. You've been told this repeatedly.

I've also been told that unicorns exist. But I don't believe BS.

 

[DGM]

I've also been told that unicorns exist. But I don't believe BS.

So you believe my examples above would all have the same impact on your foot? Why do I get the feeling you think "free-fall" is "speed"?

 

[excaza]

I've also been told that unicorns exist. But I don't believe BS.

Show me then, specifically, using math, where the free fall acceleration term is in the KE and GPE equations. I've asked you to do this before and you've ignored it.

 

[cmatrix]

So you believe my examples above would all have the same impact on your foot? Why do I get the feeling you think "free-fall" is "speed"?

I believe neither. I get the feeling your reasoning problems are due to not understanding the difference between "all" and "all available".

 

[Newtons Bit]

GPE and KE have absolutely nothing to do with free fall. You've been told this repeatedly.

And you would be incorrect.

The sum of energy of a structural body is:
KE = 1/2 m * v^2
PE = m*g*h1
SE = strain energy

If the body moves to a position h2 = h1 - 10ft then it stands to reason that:

m*g*10ft = 1/2 * m * v^2 + SE

If SE ~= 0 then:

m*g*10ft = 1/2 * m * v^2

or:

v = 25.4 ft/sec

An object that travels 10 ft, with a constant acceleration and has a final velocity of 25.4ft/sec will take a total time of 0.787s.

This results in an acceleration of 32.2 ft/sec^2 or g.

Of course, that's a bunch of convoluted math to say that if SE ~= 0 then the acceleration is equal to g. Which is true and is what happened to WTC7. For a brief time, it accelerated at very nearly g (and sometimes more than g depending upon which point of the building one measures) because 8 stories of columns failed at nearly the same time.

 

[beachnut]

The problem is not with me. I understand that converting some of the available GPE to kinetic energy means the object will not be in free fall.

What?

 

[triforcharity]

Smoke emanating from a building for hours with little sign of flames on its active side and next to no flames on any other side of the building indicates what kind of fire?

Thanks.

A fire in the interior of the building. A fire that you do not want to see. Sorry your Trutherism is preventing you from seeing that.

 

[excaza]

And you would be incorrect.

The sum of energy of a structural body is:
KE = 1/2 m * v^2
PE = m*g*h1
SE = strain energy

If the body moves to a position h2 = h1 - 10ft then it stands to reason that:

m*g*10ft = 1/2 * m * v^2 + SE

If SE ~= 0 then:

m*g*10ft = 1/2 * m * v^2

or:

v = 25.4 ft/sec

An object that travels 10 ft, with a constant acceleration and has a final velocity of 25.4ft/sec will take a total time of 0.787s.

This results in an acceleration of 32.2 ft/sec^2 or g.

Of course, that's a bunch of convoluted math to say that if SE ~= 0 then the acceleration is equal to g. Which is true and is what happened to WTC7. For a brief time, it accelerated at very nearly g (and sometimes more than g depending upon which point of the building one measures) because 8 stories of columns failed at nearly the same time.

A ball rolling down a ramp of that same height will have the same kinetic energy at the bottom as the ball dropped straight from the height. The acceleration will not be g. GPE and KE are not linked to FFA.

 

[Newtons Bit]

A ball rolling down a ramp of that same height will have the same kinetic energy at the bottom as the ball dropped straight from the height. The acceleration will not be g. GPE and KE are not linked to FFA.

They are when the fall is (mostly) vertical. The only difference from a ramp and a vertical fall is the direction of the velocity vector. The magnitude will remain the same. Assuming no frictional losses in any event.

The point I'm making is that if the structure falls roughly straight down at approximately g then there is little resistance provided by the structure. cmatrix is stating that (more or less correctly). His problem is that he cannot fathom an event that would cause 8 stories of weakened columns to fail roughly at the same time.

 

[excaza]

The point I'm making is that if the structure falls roughly straight down at approximately g then there is little resistance provided by the structure. cmatrix is stating that (more or less correctly). His problem is that he cannot fathom an event that would cause 8 stories of weakened columns to fail roughly at the same time.

No, his argument (his original one, anyway) is that an object that has converted all its potential energy into kinetic energy must have been in free fall. This is not true. For a vertical fall, yes, but not in general.