Falling objects can be faster than free fall

[Landru]

I think @Landru would agree with me that this off-topic to the current thread. If you want to start another one about evidence & authority in debunking, that's something I would love to discuss.

No, I don't. And please stop paraphrasing what people say. Quote them directly.

 

[qed]

It's bunk if it is false.
If it is true, but the evidence has been deleted, then it is unprovable for the time being.
Not bunk.

I do remember the same evidence that @econ41 remembers: It had been presented and linked to in a couple of fora, but one or two of those fora have gone out of existence, and the storage space linked to that contained the data and analysis has been discontinued.

So that's a shame. It means we can't, for the moment, present that data for scrutiny, and you can dismis caims of over-g at WTC out of hand.
But to claim they are bunk would require for you to falsify over-g.

There is no evidence so it is bunk.

You cannot present any evidence, only vague memories of your Halcyon days on "fora" in 2004! Can you imagine if anyone else came to MetaBunk and presented vague memories of no longer existing "fora" as evidence!

One cannot debunk vague memories.

There is a simple argument why over-g is at least plausible (and in my opinion probable):

No skeptic cares!

Without evidence there is absolutely no point in pondering extra mechanisms that could explain something for which we have no evidence that it even exists. We will go in circle forever. Use Occam's Razor! Do not add extra hypothesises.

I will repeat: this WTC7 over g bunk exists only on MetaBunk.

PS: We have been down this route before right? If you really want to do it again, please present the evidence clearly and I will attempt to reproduce the experiment again.

Else please stop it.

 

[Oystein]

Skeptics say that? Truthers do.
And they have free fall in mind when they say that.
But your definition just means net zero external force.

Now consider my other example: a rod supported on one end.

Even if, by your definition, the center point of the rod suffers "no resistance", would you say it is in free fall?
What about the other points on the rod, undergoing accelerations from 0g to ~2g? Are they in any different from the 1g center point?

The numbers you put there are wrong.
The center point of the rod (which would be its center of gravity) most definitely is at <g.
The far end is at g < a < 2g.
I don't recall the correct values or formulas, but a factor 1/3 features somewhere. Is the loose at at 1 1/3 of g? something like that.
But only while the rod is horizontal.
It's less than that wen the rod is at an angle above or below horizontal. This is easy to understand: When the angle is 90° or -90^, it is obvious that there would be full resistance communicated to the loose end, and a = 0 then.

 

[Oystein]

There is no evidence so it is bunk.

No. Nonsense.

There are of course claims that are perfectly true even while there is no evidence available.

For example: all the witnesses to my birth are dead already.
No camera recorded my birth.
Suppose there was a fire at the local registry of births and my birth certificate was lost.
And now there exists no evidence I could present to prove my birthday.
But clearly remember what my birthday is, and my mother, who was a witness, told me it.
If I claimed my birth is the soandsoth of month youknowwhichImean in the year wellthatyear (insert specific numbers for my true birthday)
And if my siblings also aree they remember there used to be evidence.
Would my claim be bunk?

No. Nonsense.

Lacking evidence is not equivalent to being bunk.

 

[Oystein]

If I'm understanding you correctly you are saying that the rope ladder that hits the table is not in free fall.

You understand that correctly.

There seems to be some technical sense in which that is true

That some "technical sense" is staring you in the face and comes with a clear and onbious violation of the simplest definition of "free fall".

An object is in free fall if and only if the only external force acting on it is gravity.​

Since the ladder most obviously hits the table, or ground, and the bottom rungs are suddenly stopped by that, there is your most obvious external force other than gravity acting on the ladder -> NOT FREE FALL

And the same would be true for the top rung, or any rung: Since we observe that acceleration of the top rung is >g (its center of gravity falls faster than the other ladder that does not tough any obstacle and therefore is in free fall, ignoring air resistance), that tells us that the strings are tugging on it, and the rung, observed in isolation, clearly experiences a force other than gravity -> NOT FREE FALL

and some (net negative) sense in which the "resistance" that the bottom rung encounters is transmitted to the top rung. But, to tell you the truth, I'm having a hard time following the argument and why you think it is important.

Let's drop the "important" bit - whether or not something is "important" is a matter of personal judgement, of purpose, of bona fide opinion, not a fact.

Do you understand the definition of "free fall" I gave above - what with there being only one force, gravity, acting from the outside on an object, and none other?
Do you agree this definition is correct, and that we should use it, and use it consistently?

If so, then do you understand that an obect that is in actual free fall and experiences only one external force, gravity, will always accelerate at exactly g - gravitational acceleration in the local field of gravity?
And do you understand that this applies strrictly ONLY to its center of gravity, not to arbitrary points on its surface - because for example the object could be rotating.?

 

[econ41]

The numbers you put there are wrong

I'm getting older and slower but I still think the ratio of those motion vectors is defined by - fixed by - geometry. Hence 2:1.

But I've been wrong before...

 

[Oystein]

I'm getting older and slower but I still think the ratio of those motion vectors is defined by - fixed by - geometry. Hence 2:1.

But I've been wrong before...

The ratio is correct (if the forced end is fixed and moves neither up nor down), but @Mendel didn't indicate merely a ratio. He indicated precise numbers. 1g and 2g, with g being a constant the value of which we know with good precision. 9.805 m/s^2 is the best number I have for New York City - but whereever you do the experiment that Mendel sketches there, g is a fixed number there, and the acceleration of the lose end is not 2g, it's less than that, and the acceleration of the center of gravity is not 1g, it's less than that. Even while the ratio of accelerations between loose end and mid-point is 2:1.
Perhaps the true values are 4/3 g and 2/3 g. Something like that.

 

[econ41]

Mmmm.. Got it thanks. I wasn't even thinking about quantification. The ratio is more than sufficient for the level of argument that I prefer as SOP.

Note that I gave myself away - I actually revealed my thinking when I said "the ratio .... is defined.."

 

[Mendel]

The ratio is correct (if the forced end is fixed and moves neither up nor down), but @Mendel didn't indicate merely a ratio. He indicated precise numbers. 1g and 2g, with g being a constant the value of which we know with good precision. 9.805 m/s^2 is the best number I have for New York City - but whereever you do the experiment that Mendel sketches there, g is a fixed number there, and the acceleration of the lose end is not 2g, it's less than that, and the acceleration of the center of gravity is not 1g, it's less than that. Even while the ratio of accelerations between loose end and mid-point is 2:1.
Perhaps the true values are 4/3 g and 2/3 g. Something like that.

I didn't say the rod was uniform...

However, your numbers still exhibit the main feature: that there's a point on thd rod accelerating at 1 g, while left and right of it are otherwise indistinguishable points accelerating at more and less than 1g.

 

[Scaramanga]

In the 9/11 discussions, "free fall acceleration" is often treated as a kind of speed limit for gravity-driven falling objects. But that's a misconception. Watch this short video:

Source: https://youtube.com/watch?v=n8WxkqMRgS4

Because the ladder on the left impacts a table, it is no longer in free fall, and therefore mechanical effects can then cause acceleration or deceleration.

Nothing about the WTC collapses was free fall (excepting the parts ejected to the side that fell through clear air, which came close). Therefore, free fall acceleration is neither a necessity nor a limit.

The falling ladders fall at different rates for much the same reason that the objects in circular motion in this video don't ( contrary to what so many believe ) fly off in a straight line tangent when the line is released. In particular the section with the slinky around 5:27 relating to tension versus center of mass...


Source: https://www.youtube.com/watch?v=AL2Chc6p_Kk&t=1s

 

[Mendel]

In particular the section with the slinky around 5:27 relating to tension versus center of mass...

What's causing the interesting behavior here is the fact that there are internal forces at play.

Content from External Source

However, that's not true of the falling ladders. If the left ladder never hit the table, it (and all of its parts) would keep falling at g, in true free fall, with zero internal force, as the ladder on the right does. It's the external force of the table hitting it (from the ladder's frame of reference, which is a valid inertial frame!) that adds the extra acceleration.

@Oystein explained this in post #3 with the pencil and the bottle caps.

 

[Mendel]

No. Nonsense.

There are of course claims that are perfectly true even while there is no evidence available.

For example: all the witnesses to my birth are dead already.
No camera recorded my birth.
Suppose there was a fire at the local registry of births and my birth certificate was lost.
And now there exists no evidence I could present to prove my birthday.
But clearly remember what my birthday is, and my mother, who was a witness, told me it.
If I claimed my birth is the soandsoth of month youknowwhichImean in the year wellthatyear (insert specific numbers for my true birthday)
And if my siblings also aree they remember there used to be evidence.
Would my claim be bunk?

No. Nonsense.

Lacking evidence is not equivalent to being bunk.

You were born. That is an ordinary claim which requires no evidence.
Thus, we know your birthday exists.
Then we go by the preponderance of the evidence (the witness statements etc.) to determine what that likely is.

The >g claim is not ordinary, and won't be considered true unless proven. Your statement of "I remember that there was a proof, but not what it was" is bunk. It speaks to your personal belief, that's all.

Similarly, we never disprove that there are alien visitors on Earth. It might be true, and we just lack the evidence of it. We debunk the claim of evidence.

The difference is that the >g claim is somewhat falsifiable, while the "alien visitors" claim is not.

 

[FatPhil]

I don't recall the correct values or formulas, but a factor 1/3 features somewhere. Is the loose at at 1 1/3 of g? something like that.

This sounds like the "centre of percussion", which for a uniform rod pivoting about one end is 2/3 of the way along. However, the dropped stick scenario doesn't have a pivot, so I suspect the more important position is just the centre of mass.

(I can't promise anything, but I'm going to charge up my camera battery, and see if I can capture some high-speed footage of such an impact - I have a drumstick and a rigid railing, and the "whiplash" effect on the far end seems quite impressive. I could even try my new timeslicing technique on such a vid. However, it's saturday lunchtime, and my immediate priority is pizza.)

 

[FatPhil]

the ladder's frame of reference, which is a valid inertial frame!

Nope, it's accelerating.

 

[econ41]

You were born. That is an ordinary claim which requires no evidence.
Thus, we know your birthday exists.
Then we go by the preponderance of the evidence (the witness statements etc.) to determine what that likely is

Take care with drifting objectives. @Oystein's illustrative analogy is similar to one I have used many times to parody faulty logic used by others in actual debate. The logical error in the actual debate is the issue for debunking - not the side trail of nitpicking a humorous analogy.

.The >g claim is not ordinary, and won't be considered true unless proven.

Be careful as to which ">g claim" you refer to. There are two currently "on the table"
First is the generic claim of the OP that "over G" is a phenomenon that can occur. The OP demonstrates proof of that generic claim. (And, BTW, avoiding potential implications, it is not the only "proof" - there are many.)
Bottom line I don't think anyone here is disputing the possibility of the "over G" phenomenon.

Second are claims related to whether or not "over G" occurred at WTC.

My position and Oystein's position as I understand it, has for some years been, that "over G" is plausible in the WTC scenario. Neither of us claims proof. We claim plausible. And because it is plausible it must be included in the range of possible features of WTC7 collapse.

We are claiming "over G is plausible and must be considered" so the actual claim that is open to rebuttal is that claim. If you need to rebut what we actually claim the necessary counterclaims are that "over G" is not possible and/or the counterclaim that "over G" should not be considered.

Then, if we re-frame the debate to what Oystein and I have actually said we can consider the strongest points of disagreement as raised by @qed
These two are simply false:

There is no evidence so it is bunk.

I will repeat: this WTC7 over g bunk exists only on MetaBunk.

Both are blatantly untrue. And there is no need at this stage to address QED's remaining more personal or hostile comments.

 

[Mendel]

Then, if we re-frame the debate to what Oystein and I have actually said

f) And here, we can apply what we learned in above experiments: The UPward acceleration of the core-side of the floor beams causes a DOWNward acceleration of their perimeter ends in addition to freefall, and that impulse is, IMO, what makes the perimeter accelerate, briefly, at >g!

That's a clear claim. Without evidence.

 

[Mendel]

Nope, it's accelerating.

When it hits the table, yes.

Article:

In classical physics and special relativity, an inertial frame of reference (also called inertial space, or Galilean reference frame) is a frame of reference not undergoing any acceleration. It is a frame in which an isolated physical object—an object with zero net force acting on it—is perceived to move with a constant velocity or, equivalently, it is a frame of reference in which Newton's first law of motion holds.[1] All inertial frames are in a state of constant, rectilinear motion with respect to one another; in other words, an accelerometer moving with any of them would detect zero acceleration.

Source: https://en.m.wikipedia.org/wiki/Inertial_frame_of_reference

Before the ladder hits the table, I think Newton's first law of motion holds. I don't think an accelerometer could detect anything. I believe there'scnet zero force acting on it.
Where am I wrong?

I believe that any object in free fall (that is not rotating) is inertial.

 

[econ41]

That's a clear claim. Without evidence.

But not the claim my comments referred to. Hence my concern about changing objectives or "moving the goalposts".

The Oystein statement you quote was from a section where Oystein said:

Here is my usual take. Consider:

And he described how your OP example could be applied in the explanation of WTC7 collapses. Supporting the validity of your OP claim, which I have also supported. It was not a claim that needed evidence in the context where it was made. Simply showing how your OP example would fit into a reasoned argument.

He concluded:

I'd be glad if someone could draw graphics here and there. That's not my forte.

and in a subsequent post, I committed the Metabunk sin of referring to previous work of my own which I can no longer access.

And none of that critique of history addresses the two claims which are the current legitimate topics of discussion that my post refers to.

 

[DavidB66]

I believe that any object in free fall (that is not rotating) is inertial.

The claim was about the frame of reference, not the object. A frame of reference in which the free-falling object is static would not be an inertial frame as usually defined*.

*You may be thinking in terms of Einstein's Principle of Equivalence, which implies that a set of objects all of which are falling freely in the same gravitational field will interact with each other in the same way as if they were in an inertial frame. (Incidentally this was already recognised implicitly by Newton, Corollary 6 to the Laws of Motion.) But that would not apply to other objects, not part of the freely-falling set. And even for a set of objects all in free fall, it only strictly applies to a frame of reference small enough that the gravitational field can be regarded as uniform.

 

[qed]

For those who wish to see the quality of the original debate around the "evidence" of over g presented by 9-11 conspiracy theorist femr2, here are the links:
http://www.internationalskeptics.com/forums/showthread.php?postid=8312710#post8312710
http://www.internationalskeptics.com/forums/showthread.php?t=182833
You will see some familiar names.

The footage of the WTC7 that is under analysis can be seen at the 14 second mark of this NIST video:


I have attached femr2's data obtained by his subpixel tracking as well that the Dan Rather's data set.

For a debunk/list-of-problems with femr2's approach, see this this locked thread on MetaBunk:
https://www.metabunk.org/threads/acceleration-greater-than-g.5635/

Note that simple pixel tracking as performed by NIST, yields maximal acceleration close to but less than g.

 

[qed]

@econ41 You ask us to suspend our skepticism and accept your assessment that femr2's "experiment" proves the corner of the penthouse collapsed at times faster that gravity, despite presenting us with no evidence (I have posted some raw data and amateur discussion above), and no argument as to why femr2's data analysis is so strong that it must be accepted as fact.

I am sorry, but I for one cannot do that.

 

[qed]

@econ41 Why should I accept as scientific fact that the corner of the penthouse fell at times faster than g?

 

[econ41]

@econ41 Why should I accept as scientific fact that the corner of the penthouse fell at times faster than g?

How should I know? Especially when you deny it is even plausible? And I have made no such claim.
I certainly think it is highly probable. Even if we disregard measurements other than NIST and Chandler's. I could not rigorously "prove" it did NOT occur even based only on NIST and Chandler's crude data.

I have clearly stated my position many times over many years and on several forums. Including a couple of times in this thread.
It is generically plausible as you have agreed. I think it is possible, even likely for WTC7. I cannot prove it with any rigor.

Ironically the reasons why I cannot present rigorous proof are the same reasons some people including you claim it is not possible.
It should be obvious which position is logically sustainable.

 

[qed]

@econ41 Why should I accept as scientific fact that the corner of the penthouse fell at times faster than g?

How should I know?

OK, then I will treat it us bunk until evidence suggests otherwise.

Especially when you deny it is even plausible?

Why straw-man me after directly asking me this earlier? I do not deny it is impossible, but that is a heck of a gap to probable.
And "plausible" seems a strange term to use: surely we look to the fall data to see if it happened, not speculate about the plausibility of possible mechanisms? I would not even consider extra mechanisms for over g until presented with strong evidence it actually happened!

And I have made no such claim.
I certainly think it is highly probable.

That is a very strong claim. Highly probable! How high and how did you calculate the probability? What did you weigh up?

That is the claim I feel we should be skeptical about and not take your authority on.

Even if we disregard measurements other than NIST and Chandler's. I could not rigorously "prove" it did NOT occur even based only on NIST and Chandler's crude data.

Yet you advocate for "highly probable" from such crude noisy data! Error bars, sigma value? What sub-pixel tracker was used. How accurate is that sub-pixel tracker? Is sub-pixel tracking appropriate to use when the camera is shaking and hence the point-of-interest is not moving smoothly but jumping around? Etc!

I have clearly stated my position many times over many years and on several forums. Including a couple of times in this thread.
It is generically plausible as you have agreed. I think it is possible, even likely for WTC7. I cannot prove it with any rigor.

Yet you have continued to advocate for this position for 10 years, even delivering papers at truther conferences, right? At the barest minimum, I think you have become biased towards this position due to your personal involvement with the truthers. You used to explain how over g disproves controlled demolition, right?

Ironically the reasons why I cannot present rigorous proof are the same reasons some people including you claim it is not possible.
It should be obvious which position is logically sustainable.

No one claims it is impossible! (straw-man!)
I claim there is no scientifically sustainable evidence that it ever happened to the corner of the penthouse during this WTC7 collapse!
WTC7 over g has not been shown to have even happened in any reasonably scientific manner, so why play with explanations for it? That is counting angels on a pin head!
If the evidence shows it does exist, then we look for why!

Based on your answers, I will continue to take the skeptical position on WTC7 over g, and would encourage others to do so as well. I will also continue to challenge you senior members whenever you bring it up.

I have asked you repeatedly to please refrain but you seem unable to stop advocating for this bunk.

 

[Mendel]

And even for a set of objects all in free fall, it only strictly applies to a frame of reference small enough that the gravitational field can be regarded as uniform.

Well, that's always true for any inertial frame, isn't it?

If I put a ball on a turntable, it starts moving on its own, due to pseudo-forces (coriolis, centrifugal) that are really inertia.
If I put a ball outside my window, it starts moving on its own, due to pseudo-forces, while the ball is really moving inertially along space curvature.
If I release a ball inside the ISS, or on a parabolic flight, that ball obeys Newton's first law, because the ball and its frame of reference are in free fall.

 

[FatPhil]

When it hits the table, yes.

Article:

In classical physics and special relativity, an inertial frame of reference (also called inertial space, or Galilean reference frame) is a frame of reference not undergoing any acceleration. It is a frame in which an isolated physical object—an object with zero net force acting on it—is perceived to move with a constant velocity or, equivalently, it is a frame of reference in which Newton's first law of motion holds.[1] All inertial frames are in a state of constant, rectilinear motion with respect to one another; in other words, an accelerometer moving with any of them would detect zero acceleration.

Source: https://en.m.wikipedia.org/wiki/Inertial_frame_of_reference

Before the ladder hits the table, I think Newton's first law of motion holds. I don't think an accelerometer could detect anything. I believe there'scnet zero force acting on it.
Where am I wrong?

I believe that any object in free fall (that is not rotating) is inertial.

Well, there's a difference between a Newtonian IRF and an Einsteinian IRF. You seem to be taking an Einsteinian view, but I don't think you've absorbed the consequences of such a stance. An Einsteinian perspective makes all your normal IRFs not IRFs any more (as gravity's there, and the equivalence principle states that that is the equivalent of accelerating).

From a Newtonian perspective, it's undergoing acceleration, it's immediately excluded. However, even when you flip to a GR perspective, the quoted paragraph doesn't apply as it's not an isolated physical object. The paragraph even states explicitly "In classical physics and special relativity ...", so you can't hold a GR stance and support your statement with the above statements, chose one regime or the other, not both. You can know you're accelerating though, even if you take a GR perspective: an accelerometer would detect a lack of gravitational attraction towards the massive object. This apparent violation of the known laws of gravitation tells you something about your motion, namely that you're accelerating. If you're in a closed lift, and don't know that there's a massive object below you, you can still detect an anomaly that implies you are in an accelerating frame of reference, not an inertial one, as a charged particle would radiate an electromagnetic field.

 

[FatPhil]

The claim was about the frame of reference, not the object. A frame of reference in which the free-falling object is static would not be an inertial frame as usually defined*.

*You may be thinking in terms of Einstein's Principle of Equivalence, which implies that a set of objects all of which are falling freely in the same gravitational field will interact with each other in the same way as if they were in an inertial frame. (Incidentally this was already recognised implicitly by Newton, Corollary 6 to the Laws of Motion.) But that would not apply to other objects, not part of the freely-falling set. And even for a set of objects all in free fall, it only strictly applies to a frame of reference small enough that the gravitational field can be regarded as uniform.

A gravitational field that is uniform has no slope, no "down" vector; there's no direction objects would be accelerated in. This is counterfactual to the problem statement.

 

[econ41]

@Thomas B Your main point is valid. It highlights the need to be clear as to the definition of terminology.

Even this comment could be challenged:

A bullet shot straight down will "be (moving) faster than freefall";

... since "faster" is usually used in reference to "speed" AKA velocity. When the context is acceleration.

 

[DavidB66]

A gravitational field that is uniform has no slope, no "down" vector; there's no direction objects would be accelerated in. This is counterfactual to the problem statement.

By a uniform gravitational field I meant one in which the direction and strength of the gravitational force is uniform, i.e. which does not vary in different parts of the field. I think this is consistent with respected usage, but even if it isn't, it is an intelligible concept. In Einstein's 'falling elevator' thought-experiment the elevator and its contents are all subject to a uniform gravitational field (in this sense) in the reference frame of the earth, but the contents, including people (if any), would not experience any gravitational force with respect to the elevator. Until they hit the ground!

 

[DavidB66]

Well, that's always true for any inertial frame, isn't it?

That depends what you mean by an inertial frame. If we reject Newton's Absolute Space, there is probably no way of defining an exactly inertial frame, but for practical purposes some frames come closer to the ideal than others. Over a short period of time the surface of the earth would be closer to the ideal than the surface of a turntable, a set of co-ordinates fixed in relation to the sun would be better (post-Copernicus!) than the surface of the earth, and co-ordinates fixed in relation to the Milky Way galaxy would be better still.

If I understand General Relativity correctly (which is unlikely), in principle large-scale frames of reference are rejected as invalid, and only 'infinitesimal co-ordinate systems' should be considered. In practice (say, for astronomical purposes) this would be highly inconvenient, and quasi-Newtonian methods are used, or the Lorentz-Einstein transformations if high velocities are involved.

Added: I found this dictionary definition of 'inertial coordinate system' (source here https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100002406#:~:text=The system of coordinates that,rest in the coordinate system. )

The system of coordinates that is used in an inertial reference frame, normally in the special theory of relativity. The three space coordinates are usually Cartesian coordinates (x, y, z), and the time coordinate is the time as measured by an observer at rest in the coordinate system. In astrometry, an inertial coordinate system is a reference frame formed by assigning coordinates to specific observable objects, such as the positions and proper motions of stars in a fundamental catalogue

Second added: (face-palm) I should have checked earlier to see if there is a Wiki entry on 'inertial frame of reference'. There is:

https://en.wikipedia.org/wiki/Inertial_frame_of_reference

 

[econ41]

In Einstein's 'falling elevator' thought-experiment the elevator and its contents are all subject to a uniform gravitational field (in this sense) in the reference frame of the earth, but the contents, including people (if any), would not experience any gravitational force with respect to the elevator. Until they hit the ground!

There is a local variant we discussed in 2015:
https://www.metabunk.org/threads/acceleration-greater-than-g.5635/post-143011

 

[delnvc]

A bit of a side question, but I have several times asked 9/11 Truth followers WHY they think it is significant that "the towers fell at free fall speed." What do they think this proves? Never got an answer -- presumably the folks I've talked to just saw the claim made, and that THIS MEANS SOMETHING, and didn't go any further into it.

Whether or not they actually fell at "free fall speed," does anybody know what CTers on 9/11 thank it would prove if they did in fact fall like that?

Never got any answer, are you serious? Resistance ofc.

 

[econ41]

If I understand General Relativity correctly (which is unlikely), in principle large-scale frames of reference are rejected as invalid, and only 'infinitesimal co-ordinate systems' should be considered. In practice (say, for astronomical purposes) this would be highly inconvenient, and quasi-Newtonian methods are used,

I take an even more pragmatic approach.
As an 82 years old engineer - qualified in both civil and military - I learned and practiced in the Newtonian domain.

Makes my life a lot easier. And doesn't limit my comprehension of the scale of earth-bound phenomena we discuss here. Especially the current topic of building structural failures and WTC collapses.

 

[FatPhil]

By a uniform gravitational field I meant one in which the direction and strength of the gravitational force is uniform, i.e. which does not vary in different parts of the field. I think this is consistent with respected usage, but even if it isn't, it is an intelligible concept. In Einstein's 'falling elevator' thought-experiment the elevator and its contents are all subject to a uniform gravitational field (in this sense) in the reference frame of the earth, but the contents, including people (if any), would not experience any gravitational force with respect to the elevator. Until they hit the ground!

Yes, but if you're taking an Einsteinian view, you have to accept that even if the earth were stationary, me sitting here flipping coins up and down in idealised parabolae would *not* be an inertial reference frame. Which goes very much against the usual usage, which is thinking of Newtonian (more accurately Galilean) IRFs. You really can't mix the two regimes, GR breaks the concept completely - one has gravity as a force, the other doesn't.

 

[Scaramanga]

@Oystein explained this in post #3 with the pencil and the bottle caps.

No....I don't fully accept the explanation in #3. He's on the right track. When the wider ends hit the table that yanks the shorter end of the link, giving a downward pull....yes. But...I can't help but feel that the larger part of the effect is actually due to the rungs piling up and that continually reduces the distance the remaining rungs have to travel to create said effect. Very little effect is actually seen until almost 10 or 11 rungs have piled up. So I think there are two effects at play. The one described in #3, which is somehow being enhanced as time does by with the rungs piling up and making the hit distance shorter.

 

[Mendel]

No....I don't fully accept the explanation in #3. He's on the right track. When the wider ends hit the table that yanks the shorter end of the link, giving a downward pull....yes. But...I can't help but feel that the larger part of the effect is actually due to the rungs piling up and that continually reduces the distance the remaining rungs have to travel to create said effect. Very little effect is actually seen until almost 10 or 11 rungs have piled up. So I think there are two effects at play. The one described in #3, which is somehow being enhanced as time does by with the rungs piling up and making the hit distance shorter.

Remember that you're looking at a 3rd order effect.

The impact forces generate a small acceleration difference (1st order).

The acceleration difference accrues to cause a speed difference over time (2nd order).

The speed difference over time accrues to a location offset that you can see (3rd order).

So the "wait time" before the effect becomes visible is these small effects accruing until the speed difference is enough to result in visible displacement.

 

[Mendel]

Isn't there something wrong in the title of this thread? Is it correct to say that falling bodies can be faster than free fall?

In a first for you, you managed to misquote the thread title.
The meaning of the thread title ("Falling objects can be faster than free fall") is immediately clear from the OP #1, because the video clip makes it clear.
It tallies with the use of "falling" by the truthers who take measurements of the roof line to be indicative of how the facade falls.
If every fall was a free fall, we wouldn't need the word "free fall". In common parlance, many falls are somewhat impeded.

@Thomas B Your main point is valid. It highlights the need to be clear as to the definition of terminology.

No, it's not valid. The terminology is clear.

... since "faster" is usually used in reference to "speed" AKA velocity. When the context is acceleration.

In context of the ladder video, the difference of acceleration results in a difference of speed. The use of "faster" is appropriate.
We observe the speed difference and infer an acceleration difference as the cause.

So I'll step away and maybe reread this thread in a few weeks. Happy debunking!

I'm disappointed that you abandoned this plan. But since you did, let me reply to this:

I don't know why you insist on doing things this way, but it's not my thing.

I will keep on calling out your opportunistic arguments by quoting you to make the contradictions and shifting of positions and arbitrariness of your standards apparent to all readers. I get that you don't like that. I suggest that the way to fix it is to rethink the way you engage with arguments.

I have nothing against you personally, I don't even know you. But I know that your interaction patterns rarely contribute anything of interest to the forum.

The rungs of the ladder aren't just "falling", right? Usually, "falling" means propelled only by gravity, and resisted by the medium through which the body is falling. But that's not what's happening in this little mechnism.

Yes, it is what's happening. Please point out a source of propulsion that is not gravity, in the ladder video. You can't, therefore your statement is false. (Or do it with the falling rod, which also exhibits >g acceleration for its tip.)


And all this pales by comparison with your own failure to clarify yourself. To this day, I have no idea what you meant:


But hey, it's all good if you can instead make a claim that a fall that's driven by gravity isn't. It really represents your input on this forum perfectly.

 

[Landru]

Just a quick thought. Isn't there something wrong in the title of this thread? Is it correct to say that falling bodies can be faster than free fall? Isn't it more like "members of structures can move downwards faster than free fall"?

Well the title is "fallen objects" not fallen bodies. Please stop paraphrasing.

 

[qed]

In the 9/11 discussions, "free fall acceleration" is often treated as a kind of speed limit for gravity-driven falling objects. But that's a misconception. Watch this short video:

Source: https://youtube.com/watch?v=n8WxkqMRgS4

Because the ladder on the left impacts a table, it is no longer in free fall, and therefore mechanical effects can then cause acceleration or deceleration.

Nothing about the WTC collapses was free fall (excepting the parts ejected to the side that fell through clear air, which came close). Therefore, free fall acceleration is neither a necessity nor a limit.

@Mendel Why did you post this over g topic in the 9-11 Forum?

I see no connection with any particular 9-11 conspiracy claim in the OP and think it an only lead to confusion.

How do you think this might help 9-11 debunkers in the future?

 

[Thomas B]

I'm disappointed that you abandoned this plan. But since you did, let me reply to this:

I didn't mean to cause offense. I apologize.