• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Merged New video! Architects and Engineers - Solving the Mystery of Building 7

...WOW! He backs something up. First time for everything.

Thing is, they were wrong. And at the time, they didn't have 10 years of hindsight to work with.

What's your excuse?
 
I don't really know why I bother. MM is stubbornly, determinedly uneducable on this, or apparently almost any, scientific or engineering principle.

But for the others, here is a perfect example of something that "makes common sense" to someone, but is totally, 100% wrong.

Miragememories said:
Dave Thomas said:
[Dave gives example of ball tossed in air, where v=0 and a=-g at its apex.]
Click to expand...
Only if you wish to turn this into a 'red herring' of a college course David.
Click to expand...

Wrong, MM.

Dave gave you a perfect example which clearly demonstrates the difference between instantaneous a & instantaneous v.

The precise point which seems to be eluding you.

Miragememories said:
Regarding your irrelevant comparison example of the upwardly tossed ball.

There is an easy to use word in the english language which clearly describes the motion condition of your upwardly moving ball when is "falling at zero velocity over a zero period of time". It is called stopped David. From that extremely brief "stopped" condition, T=0, it will enter into a state of freefall or an acceleration of 1G.

I gather the whole thrust of your argument is to bog me down in superfluous academic excreta and to drive visitors away by boring them to death.
Click to expand...

And this is the point that is interesting to mathematicians, experimentalists and first semester high school calculus students alike.

0/0 does NOT equal 0.
It can equal any number.

The physical representation of this concept is a photograph of some object (moving or stationary) taken with a very short exposure time (e.g., short strobe pulse or very fast shutter speed).

A photo, taken at say 1/10,000th of a second shows an object. In the photo, the object does not move at all, and the time of the exposure is approximately zero. That is: d=0 and t=0.

From this photo, you can tell absolutely nothing about its velocity.

Its velocity could be zero, 1 ft/sec, 10 ft/sec, -100 ft/sec, or a million mph.

[BTW, 1/10,000th of a second is, literally, an eternity compared to a true "zero time interval". Just thought you should know.]

Miragememories said:
It does not alter the engineering facts required for WTC7 to be in a state of freefall for 100 feet.
Click to expand...

WTC7 was never "in a state of freefall for 100 feet".

This is your constant error, confusing "the building" with "its exterior walls". Until you correct this error in your head, no steps forward are possible.

This illusion is proven by the collapse of the penthouse. Maintaining this confusion is exactly why you choose to ignore the collapse of the penthouse.

Moreover, despite what Chandler says, not even the exterior walls were "in free fall".

Here (again… 200th time…) is a graph of accelerations with high resolution (i.e., all frames, instead every 5th frame):

picture.php


1. The acceleration of an object whose supports are suddenly removed (red line), versus
2. The acceleration of the north west corner of WTC7.

It's average acceleration was close to G. But it fell nothing like something in free fall.

Miragememories said:
It does not alter the fact that at least 100 feet of zero structural resistance must have existed for the NIST's WTC7 global collapse Stage 2 freefall to have occurred.
Click to expand...

once again, you don't seem to appreciate the difference between "a small number" and "zero". That is your limitation.

Miragememories said:
And I doubt it was possible, considering the rather crude video measurements available to the NIST, for them to precisely state that Stage 1 was a perfectly smooth zero to 1G acceleration over 1.75 seconds.
Click to expand...

Objects that enter free fall by some mechanism like explosive removal of their supports do NOT have their accelerations gradually increase from zero to G. This is another example of your confusing velocity with acceleration.

The velocity gradually increases. The acceleration goes instantly to G. No gradual buildup. Just like the red line in the graph above.

Miragememories said:
It is good to see you acknowledge that at Time = zero (start of Stage 1), that WTC7 had a global collapse acceleration of zero.

The use of "near freefall" to characterize the Stage 1 portion of the WTC7 collapse, is clearly intended to convey a relative value to the observed descent. This would seem to be a fair description given that after 1.75 seconds, WTC7 was in freefall.
Click to expand...

Anyone who says it was in "near free fall" during Stage 1 doesn't know what they are talking about.

Anyone who says that the acceleration increased gradually from 0 to G during Stage 1 doesn't know what they are talking about.

Miragememories said:
I make no lofty claims as to being an authority.
Click to expand...

Understatement of the month.

The vast majority of technical comments that you make are simply wrong.

Miragememories said:
Maybe if you showed some deference to the engineering reality of what amazingly happened to WTC7, David, you might earn the authority that you so arrogantly attempt to promote.

MM
Click to expand...

You haven't the qualifications, measured either by diplomas on the wall or by comprehension, to comment on "engineering reality".

Sorry for the harsh truth. But that IS "engineering reality".
 
Miragememories said:
For example, need I drag out the news story where the fire chiefs are all claiming they had no expectation that the Towers were going to collapse?

MM
Click to expand...

Really? Considering your own evidence for this clearly states there was concern for the top stories, firemen are not structural engineers, nor had they ever dealt with airlines crashing into steel framed skyscrapers; they had little idea what to expect, or the effect collapsing upper sections would have on the remainder of the building.

Also, your example is not entirely correct, according to the Naudet brothers film, after the collapse of the first tower, a madday went out to all fire units in all buildings to get out. This included all firefighters in the second tower. Obviously, after the first one came down, they knew the second would likely follow.

Guess they were right.. (Oh wait, no, they were 'in on it', right?)
 
Miragememories said:
"I guess that was your "bs baffles brains" argument, eh David?

My statements were directed to people in the world that understand that when an object is not moving, it has no velocity or acceleration.

You think you are making a great case by complicating something which is not complicated at all.

If somehow you believe all your academic posturing is going to make WTC7's 100 foot free fall drop become somehow insignificant and a realistic fire-induced expectation, than good luck to you."
Click to expand...
sylvan8798 said:
Ok, when you throw the ball up in the air at every instant it feels the attraction of gravity wanting to pull it back down. The attraction is expressed as the force F=GmM/r^2, where G is a constant, m is the mass of the ball, M is the mass of the earth, and r is the distance center-to-center from earth to ball. Inserting the approximate values for earth's mass and radius, and the constant, GM/r^2 ~ 32.2 ft/s^2 = g, or 9.81 m/s^2 = g in metric. While the ball is in motion, neglecting air resistance, this is the only force acting on it.

Newton's second law tells us that the sum of the forces acting on the object is equal to the mass of the object times its acceleration, F = ma. So on the left we have only the force F=mg described in the paragraph above. On the right we have ma. That gives us:

mg = ma

Now clearly this is true at all times during the flight of the ball, since the gravitational force is always acting. Even when the ball comes to a stop at the top. If the acceleration were somehow zero (a=0) at the top, we would have mg = 0. There would suddenly be no gravitational attraction acting on the ball. No net forces at all. This presents a problem, because Newton's first law tells us that if there are no net forces acting on the object that it continues its motion at constant velocity or remains at rest. Since the ball is "at rest" at the top of its flight, it would thus remain so. If it is not your personal experience that objects remain hanging in the air once you have thrown them up, then you must accept that the sum of the forces is not zero, and thus ma must have some value, as we have shown that a must be equal to g.
Click to expand...

Yawn.

I never said the force of gravity stopped acting on the ball, or WTC7 for that matter.

What makes no sense in your argument is the statement; "While the ball is in motion, neglecting air resistance, this is the only force acting on it."

Clearly, the ball is moving upward because of an initial force F1.

Your argument only addresses the gravitational attracting force G, gravity. You do not address the force opposing gravity. The upward force F1, which made the ball oppose gravity in the first place.

So at the point where the ball stops, we have the canceling sum of the two forces (F1, upward, and G, downward, gravitational), I'll use illustrative numbers here, (+1) + (-1) = zero.

So based on Newton's second law, this sum of the two forces, zero equals the mass M times its acceleration a. We know the mass M is a real value greater than zero, so. if 0=M x a, then a must also equal zero.

So, as I previously stated, an object that is not moving, "has no velocity or acceleration."

That condition is met when the upward force, F1, equals the gravitational force, T=zero for my purposes.

velocity = the speed of something in a given direction.

acceleration = the increase in the rate of speed of something.

So, for a time of zero duration, and a velocity of zero, there is zero increase in the rate of speed.

Thus acceleration is also zero.

Back to you sylvan8798

MM
 
Sorry I feel nub for asking, but can someone explain to me why, in two places, does the green line move above 0 acceleration? Did WTC7 begin to fall upwards at some stage? or is this just representing the building is resisting G for these brief moments?

picture.php
 
Let's look at the opinion of someone who witnessed the events of 9/11 first hand. He is both a fire fighter and a structural engineer who had studied the design of the twin towers prior to 9/11.

Here are his recollections of that day.
 
Last edited:
tfk said:
This is your constant error, confusing "the building" with "its exterior walls". Until you correct this error in your head, no steps forward are possible.

This illusion is proven by the collapse of the penthouse. Maintaining this confusion is exactly why you choose to ignore the collapse of the penthouse.
Click to expand...

MM, I think you should put aside the acceleration vs. velocity argument and think about what tfk says here. Only when this is understood can you properly address the "free fall" problem.

ETA: This is also why this does not look like a classic "Controlled Demolition".
 
Last edited:
Miragememories said:
[qimg]http://img833.imageshack.us/img833/6533/noconcernofwtccollapsea.jpg[/qimg]

MM
Click to expand...

Wow, human beings were wrong! So MM what do you imagine this proves? Clearly they did not expect the towers to fail or else they would not have sent the firefighters up now would they. One tower fails and they learn big lesson the hardest way possible.....they try to get their guys out of WTC1 but still lose more and you are surprised they take zero changes with WTC7???????

Whats the worst case if they were wrong and 7 didn't fail? Yes this might have cost a few survivors in the debris pile because they didn't get there sooner but what if they had tried fighting it and lost another hundred when it did fail?

They guessed right and saved hundreds more lives and you accuse them of being part of a mass murder.......:mad:.
 
funk de fino said:
Miragememories said:
So, for a time of zero duration,

MM
Click to expand...
Did you really post that? Wowzer.
Click to expand...
That wasn't the worst part in his post. You could say that this was just clumsy wording. In fact, I wrote something similar earlier today.

Much worse is this new proof of scientific illiteracy:
Miragememories said:
What makes no sense in your argument is the statement; "While the ball is in motion, neglecting air resistance, this is the only force acting on it."

Clearly, the ball is moving upward because of an initial force F1.
Click to expand...
MM hasn't understood Newton's first law at all.

And everything that follows in that post goes only downhill from there.
 
Oystein said:
That wasn't the worst part in his post. You could say that this was just clumsy wording. In fact, I wrote something similar earlier today.

Much worse is this new proof of scientific illiteracy:

MM hasn't understood Newton's first law at all.

And everything that follows in that post goes only downhill from there.
Click to expand...

If you are going to "talk the talk" Oystein.

"Walk the walk".

Rip my reply in that thread to shreds by proving the content is in error rather than just personalizing.

Here ya go;
http://www.internationalskeptics.com/forums/showpost.php?p=7748886&postcount=1707

MM
 
triforcharity said:
It's not a roll playing video game. It's an organic process.

Do you remember this?

You said, and I quote

Which, is incorrect. Time, temperature, humidity, wind speed, direction, variable wind patterns, fuel load, fuel placement, etc. etc. etc. ALL must be accounted for. A fire will progress differently with just slight alterations to any one of these variables.
Click to expand...

None of that is needed. Am I that much more intelligent than the debunkers?

All that is required is to use the constants in a model and develop the possible consequences of individual structural failures.

Get it? It doesn't matter how something fails because the energy that caused the failure, supposedly fire, is gone and does not assist in subsequent failures.

Think stress test.
 
Miragememories said:
My statements were directed to people in the world that understand that when an object is not moving, it has no velocity or acceleration.

You think you are making a great case by complicating something which is not complicated at all.

If somehow you believe all your academic posturing is going to make WTC7's 100 foot free fall drop become somehow insignificant and a realistic fire-induced expectation, than good luck to you.
Click to expand...
Grizzly Bear said:
Which isn't always true. You can have zero velocity with a non-zero acceleration. Gravity is a constant.
Click to expand...

Great.

In the interest of keeping this related to the thread, maybe you can show everyone how a building might collapse with zero velocity and a non-zero acceleration?

Or are all your scenarios metaphysical?

MM
 
You must log in or register to reply here.

Back
Top Bottom