Problem with cats surviving high falls

[himanshu2004@]

Problem with cats surviving high falls! :)

I've been reengaging with physics since I'd stopped formally studying it after high school (with the exception of a little bit I we had during studying computer science at university).

So I was revising my concepts of inertial frames, non intertial frames, "fictitious" forces experienced during acceleration etc, and I remembered reading in a book by Hallilday and Resnick that cats survive falls from higher places better than from lower ones (with 4-5 floors being the most dangerous height). I couldn't exactly reason out why it would happen and so I searched it on the web again and this seems to be the reason:

Cats relax after reaching terminal velocity. This causes them to spread out their posture, which reduces their terminal velocity. The further explanation given is that we can feel acceleration (and not uniform velocity).

I have a problem with this explanation, because we should only be able to "feel" acceleration when we are being accelerated by the push or pull, so to speak, of the accelerating frame. This should not happen in when accelerating due to the effect of gravity, because all of our atoms would be experiencing the same acceleration.

So, is there a problem with the explanation, and if so, what is the right explanation?


Thanks!

 

[superg33k]

The cat feels the push up of ground against gravity when it is standing on the ground. When it is free-falling, there is no push up from the ground, it feels this difference and relaxes.

 

[himanshu2004@]

Ah, you miss the question.
Why does it only relax after reaching terminal velocity?

 

[superg33k]

I'm only guessing here:

Cats priorities: 1 - land on feet, 2 - slow down
Cats dilema: Spreading its legs to slow itself down reduces the chance of landing on its feet

Once the cat reaches terminal velocity, it realizes that it will significantly slow itself down by spreading its legs, but before that point it's much more concerned with having its feet pointed downwards. (probably all instinct rather than conscious thoughts)

Then we still have the question how does the cat 'feel' it reaches terminal velocity when it can only 'feel' the force due to acceleration, which it has had ever since it was dropped. Either it feels the increased air resistance, or it reacts after falling for a certain time, or it sees the ground coming rapidly towards it.

I've never had a cat.

 

[russ_watters]

I have a problem with this explanation, because we should only be able to "feel" acceleration when we are being accelerated by the push or pull, so to speak, of the accelerating frame. This should not happen in when accelerating due to the effect of gravity, because all of our atoms would be experiencing the same acceleration.

So, is there a problem with the explanation, and if so, what is the right explanation?

If you can feel an acceleration, you can feel the difference between an acceleration and a [sudden] lack of acceleration. For falling (when vertical anyway), it's the feeling of your stomach lifting inside your abdomen.

 

[Borek]

I've never had a cat.

Nobody ever had a cat. Some people are/were owned by cats. Sometimes cats allow people to live with them, but that's all.

Now I should ban myself for OT posting.

 

[himanshu2004@]

If you can feel an acceleration, you can feel the difference between an acceleration and a [sudden] lack of acceleration. For falling (when vertical anyway), it's the feeling of your stomach lifting inside your abdomon.

1) Why should the stomach lift inside the abdomen; the stomach would be accelerated downward just as the abdomen would be. No? Wouldn't it be more accurate to say I would feel a change from experiencing weight to experiencing weightlessness. Anyway, this change would be nearly instantaneous (unlike reaching terminal velocity which would take much longer).

2) My question wasn't about the difference between the cat being at rest and suddenly entering free fall, but about what difference its reaching terminal velocity makes. As is suggested at http://ffden-2.phys.uaf.edu/211.web.stuff/Kuhns/Index.htm
and in presumably in some the works referenced (I certainly remember reading something similar in Halliday-Resnick)

 

[JaredJames]

1) Why should the stomach lift inside the abdomen; the stomach would be accelerated downward just as the abdomen would be. No? Wouldn't it be more accurate to say I would feel a change from experiencing weight to experiencing weightlessness. And this change would be nearly instantaneous (unlike reaching terminal velocity which would take much longer).

Why would everything fall at the same rate?

Your body starts accelerating downwards, but that has to be transmitted to the internal organs via a medium. Everything isn't inelastically attached to everything else.

Only in a vacuum will everything fall at the same rate.

 

[himanshu2004@]

Why would everything fall at the same rate?

Your body starts accelerating downwards, but that has to be transmitted to the internal organs via a medium. Everything isn't inelastically attached to everything else.

Only in a vacuum will everything fall at the same rate.

My question was point 2) and this is somewhat of a digression. But to reply to your post, the downward acceleration does NOT have to have transmitted to the internal organs via a medium; they are influenced by the force of gravity just as the outer body is.

 

[JaredJames]

My question was point 2) and this is somewhat of a digression. But to reply to your post, the downward acceleration does NOT have to have transmitted to the internal organs via a medium; they are influenced by the force of gravity just as the outer body is.

The force of gravity obviously doesn't, but the motion of the body does. All of your organs don't just suddenly go "we're falling" and do it immediately in time with your big toe.

 

[Drakkith]

The force of gravity obviously doesn't, but the motion of the body does. All of your organs don't just suddenly go "we're falling" and do it immediately in time with your big toe.

Umm, I'm pretty sure that's exactly how it works when you start falling. Your whole body and everything in it is accelerated at the same speed at the same time.

 

[JaredJames]

Umm, I'm pretty sure that's exactly how it works when you start falling. Your whole body and everything in it is accelerated at the same speed at the same time.

A crude analogy, imagine an air filled balloon sitting on the floor of a metal box, attached to the side by a length elastic. You suddenly drop the box. The balloon does not fall at the same rate as the box and is likely to hit the roof of the box. It is "left behind" for a short while. It's the same effect in your body.

Your whole body and everything in it may be subject to the same force from gravity, but it doesn't mean it will fall at the same rate whilst in a medium.

 

[himanshu2004@]

The force of gravity obviously doesn't, but the motion of the body does. All of your organs don't just suddenly go "we're falling" and do it immediately in time with your big toe.

I agree with that, and then it got nothing to do with "internal" organs versus "external" ones as you'd put it, but rather the "higher" parts of the body versus the "lower" parts they were resting on.
But like I said, whatever the changes due to these effects, these are almost instantaneous, and occur long before the point of reaching terminal velocity. So, why is the cat supposed to relax after reaching terminal velocity?

 

[JaredJames]

I agree with that, and then it got nothing to do with "internal" organs versus "external" ones as you'd put it, but rather the "higher" parts of the body versus the "lower" parts they were resting on.
But like I said, whatever the changes due to these effects, these are almost instantaneous, and occur long before the point of reaching terminal velocity. So, why is the cat supposed to relax after reaching terminal velocity?

Whilst accelerating in a fast car, you are constantly pinned to your seat. It is only once you reach a steady speed that you can move around normally under equilibrium conditions.

If you can feel the acceleration and then the switch to constant speed (equilibrium) it shouldn't be hard to judge.

 

[Drakkith]

A crude analogy, imagine an air filled balloon sitting on the floor of a metal box, attached to the side by a length elastic. You suddenly drop the box. The balloon does not fall at the same rate as the box and is likely to hit the roof of the box. It is "left behind" for a short while. It's the same effect in your body.

Your whole body and everything in it may be subject to the same force from gravity, but it doesn't mean it will fall at the same rate whilst in a medium.

Actually I'm pretty sure the balloon would fall at the same rate as everything else. Remember that the balloon is NOT falling through the medium, the box is. The balloon is inside the box and has no contact with anything outside, similar to your body.

 

[Drakkith]

Whilst accelerating in a fast car, you are constantly pinned to your seat. It is only once you reach a steady speed that you can move around normally under equilibrium conditions.

If you can feel the acceleration and then the switch to constant speed (equilibrium) it shouldn't be hard to judge.

Agreed. Once you reach terminal velocity you no longer feel like your falling because the resistance of the air is in equilibrium with gravity. I believe you would feel like your lying on the ground or something similar.

 

[JaredJames]

Actually I'm pretty sure the balloon would fall at the same rate as everything else. Remember that the balloon is NOT falling through the medium, the box is. The balloon is inside the box and has no contact with anything outside, similar to your body.

Train decelerating, you fall forwards.

Car accelerating, you are pinned to seat.

To take it further, when you accelerate / decelerate, the air pressure changes internally to a slight gradient - shown where a helium balloon will move opposite to acceleration.

 

[himanshu2004@]

A crude analogy, imagine an air filled balloon sitting on the floor of a metal box, attached to the side by a length elastic. You suddenly drop the box. The balloon does not fall at the same rate as the box and is likely to hit the roof of the box. It is "left behind" for a short while. It's the same effect in your body.

Your whole body and everything in it may be subject to the same force from gravity, but it doesn't mean it will fall at the same rate whilst in a medium.

That seems completely incorrect. (Ignore my previous post, it was in a different context.)

I am pretty sure that if the metal box is air-tight, the balloon would fall exactly as the same rate as the box. In any case, how is the material inside the balloon relevant?

 

[Drakkith]

Train decelerating, you fall forwards.

Car accelerating, you are pinned to seat.

None of that is like gravity. Gravity pulls everything in your body down at the same time, an accelerating train or car does not.

 

[JaredJames]

In any case, how is the material inside the balloon relevant?

Huh?

 

[himanshu2004@]

Whilst accelerating in a fast car, you are constantly pinned to your seat. It is only once you reach a steady speed that you can move around normally under equilibrium conditions.

If you can feel the acceleration and then the switch to constant speed (equilibrium) it shouldn't be hard to judge.

Incorrect again. In an accelerating car, you can feel the acceleration, because you are "pushed" by accelerating car (like I said in the starting post of the thread), and the part of you which gets pushed first pushes the other parts and so on.

Accelerating due to free fall, you cannot feel that acceleration, because nothing in your body is pushing or pulling anything.

 

[JaredJames]

None of that is like gravity. Gravity pulls everything in your body down at the same time, an accelerating train or car does not.

So now I'm curious what causes the "stomach left behind" feeling?

 

[JaredJames]

Accelerating due to free fall, you cannot feel that acceleration, because nothing in your body is pushing or pulling anything.

Air resistance? You'll get some sensation at least.

 

[Drakkith]

So now I'm curious what causes the "stomach left behind" feeling?

It most definitely is not your stomach being "left behind". I've gotten that feeling just sitting in front of an IMAX screen or right before I go over the top of a roller coaster. It is something more like excitement or fear or something.

 

[Drakkith]

Air resistance? You'll get some sensation at least.

Yes, you would be able to tell you are moving due to the air resistance, and probably tell that you are accelerating.

Now imagine if you were on one of those 747's or whatever they use to train astronauts for zero G. The plane goes into a controlled dive and you begin to free fall. Can you tell you are accelerating? Nope.

 

[himanshu2004@]

Agreed. Once you reach terminal velocity you no longer feel like your falling because the resistance of the air is in equilibrium with gravity. I believe you would feel like your lying on the ground or something similar.

I believe that might make sense. Because its only after reaching terminal velocity that the cat experiences as much "upward push" as it is used to experiencing while standing/sitting on the ground.

 

[himanshu2004@]

Air resistance? You'll get some sensation at least.

Air resistance certainly, but that's got only to do with velocity against the air. You would feel air resistance even if you were moving against air at a constant velocity.

So now I'm curious what causes the "stomach left behind" feeling?

To the extent that its a real feeling, it happens because your stomach is used the effect of feeling its weight, which makes it push downward against the abdomen. In weightlessness, the stomach is felt to be slightly closer to your chest than you're used to.
In fact, if you hung upside down, you would feel that doubly strongly.
But yes, its nothing more than that.
In any case when free falling, your stomach should feel the same that of astronauts floating peacefully in zero gravity space :)

 

[himanshu2004@]

It most definitely is not your stomach being "left behind". I've gotten that feeling just sitting in front of an IMAX screen or right before I go over the top of a roller coaster. It is something more like excitement or fear or something.

Its at least partly physical as mentioned above since it feels different from the usual state. In a roller coaster your stomach anyways does get left behind when its accelerating/decelerating, due to inertia.

 

[superg33k]

Half of these posts use the word falling as an acceleration. The other half use it as a velocity.

 

[BruceW]

The stomach "left behind" feeling is due to your body getting accelerated by a contact force - so then your body exerts a contact force on your stomach (so that it accelerates along with the body), which makes the feeling.
In gravity, with no air resistance, there is no "left behind" feeling, since gravity acts on the whole body including the stomach. In fact, there is no feeling at all. You wouldn't be able to tell the difference from just being motionless in space. (Apart from the fact that you'd be getting closer to the planet).
For the falling cat, it would feel the air resistance increasing as it sped up, then at terminal velocity, the air resistance would become constant.

 

[himanshu2004@]

@superg33k
I did a quick ctrl-F and didn't spot any ambiguity. "Falling" has always been used to mean free-falling, which is obvious given the context of this thread.

In any case, all questions seem to have been resolved a while back, so why so serious? :)

 

[himanshu2004@]

In fact, there is no feeling at all. You wouldn't be able to tell the difference from just being motionless in space. (Apart from the fact that you'd be getting closer to the planet).

The point is, we are not used to being in space, so there would be a feeling in free-fall that feels different from standing on the ground. (edit: and you'd stop feeling that difference after whatever hours/days of being in space since you'd get used to that feeling, and then being back on the Earth might feel different for a while.)

For the falling cat, it would feel the air resistance increasing as it sped up, then at terminal velocity, the air resistance would become constant.

As pointed above, I think its got more to do with the upward push due to the air resistance at terminal velocity being the same as the upward push we are used to feeling when on the ground, which is what makes the cat relax.
And as I just thought, even after the cat's terminal velocity decreases as it slows down after relaxing and spreading out, the upward force would still continue to be the same.

 

[Lsos]

As russ watters mentioned, you can definitely feel the difference between falling due to gravity and being at terminal velocity. Terminal velocity you feel just like on earth, except there's a lot of wind. Falling, or weightlessness, you feel...well, weightless. There are amusement park rides that rely on this feeling, and astronauts have to train for it. I can definitely see a cat getting freaked out and/or reacting to this. In fact, it's probably the stimulus that on their turning mechanism is tuned to.

Edit: When I started writing this, it was supposed to be right after russ watter's post on the first page. By the time I managed to post it...I see it's been already beaten to death.

 

[himanshu2004@]

Yeah, I agree. You explained it much better than Russ did (and his mentioning the word "sudden" when talking about the change in acceleration versus the lack of it didn't really help because in fact after the initial point of falling the cat experiences a gradual change in the acceleration/force it feels, till it becomes equal to what the cat feels on the ground, at which point it relaxes).
Though the thread did reach the same conclusion a while back eventually, thanks for confirming.

 

[russ_watters]

1) Why should the stomach lift inside the abdomen; the stomach would be accelerated downward just as the abdomen would be.

Again, you are thinking about it backwards: the force of gravity isn't lifting your stomach, it is just no longer pulling it down wrt the rest of your body. You notice what you lose: your legs pushing you up and the hydrostatic pressure of the weight of your guts sitting on your pelvis.

2) My question wasn't about the difference between the cat being at rest and suddenly entering free fall, but about what difference its reaching terminal velocity makes. As is suggested at http://ffden-2.phys.uaf.edu/211.web.stuff/Kuhns/Index.htm
and in presumably in some the works referenced (I certainly remember reading something similar in Halliday-Resnick)

Ok, well again, think about what changed. When a cat is standing on the ground its guts and head are hanging off its spine. In freefall, they aren't. When at terminal velocity, it is more like floating in water or lying in a soft bed: the force of gravity still tries to crush you, but is opposed by the somewhat uniform drag force instead of the structure of your bones.

 

[russ_watters]

Yeah, I agree. You explained it much better than Russ did (and his mentioning the word "sudden" when talking about the change in acceleration versus the lack of it didn't really help because in fact after the initial point of falling the cat experiences a gradual change in the acceleration/force it feels, till it becomes equal to what the cat feels on the ground, at which point it relaxes).

Yes, sorry, there is a sudden chang at the moment it jumps, then a gradual change as the acceleration decreases near terminal velocity. The whole process only takes a few seconds though.

 

[himanshu2004@]

@Russ
Yes it makes sense, I get it now

 

[harrylin]

I've been reengaging with physics since I'd stopped formally studying it after high school (with the exception of a little bit I we had during studying computer science at university).

So I was revising my concepts of inertial frames, non intertial frames, "fictitious" forces experienced during acceleration etc, and I remembered reading in a book by Hallilday and Resnick that cats survive falls from higher places better than from lower ones (with 4-5 floors being the most dangerous height). I couldn't exactly reason out why it would happen and so I searched it on the web again and this seems to be the reason:

Cats relax after reaching terminal velocity. This causes them to spread out their posture, which reduces their terminal velocity. The further explanation given is that we can feel acceleration (and not uniform velocity).

I have a problem with this explanation, because we should only be able to "feel" acceleration when we are being accelerated by the push or pull, so to speak, of the accelerating frame. This should not happen in when accelerating due to the effect of gravity, because all of our atoms would be experiencing the same acceleration.

So, is there a problem with the explanation, and if so, what is the right explanation?

Thanks!

I've seen another explanation which may be "better"; and I sure think that it's for mechanics even more fascinating.

In a nutshell, when a cat falls it does an amazing rotation act in mid air to orient its feet down - and that takes a little time. It's probably of primary importance to land on its feet.

Just Google for "falling cat" (what did you search for?) Here a few results:

http://en.wikipedia.org/wiki/Cat_righting_reflex

http://www.ocf.berkeley.edu/~barneye/kitty.html

Note: From the images it looks to me that typically cats don't spread their legs out.

Cheers,
Harald

 

[himanshu2004@]

@harrylin
Sorry I should have clarified that the "righting reflex" bit I did understand. However, the physics of falling cats involves both the righting reflex and them relaxing and spreading out more on reaching terminal velocity, which further reduces terminal velocity as result of increased air drag.
My doubts, which have now been resolved, were regarding how they feel they have stopped accelerating upon reaching terminal velocity, because one doesn't "feel" acceleration due to free fall in gravity the same way one "feels" acceleration inside say an accelerating car (which is a non-inertial frame, unlike free fall). More specifically, even though I understood that free fall would feel different from the familiar feeling of being on the ground, it took me a little time to realize that that gradually by the time of reaching terminal velocity the cat would almost "feel" similar again to what it is used to feeling on the Earth (in terms of it feeling an upward trust from below, which is absent in ideal free fall)

 

[rcgldr]

Once you reach terminal velocity you no longer feel like your falling because the resistance of the air is in equilibrium with gravity.

This is the key factor. Once at terminal velocity, the cat is probably not relaxed, but instead trying to grab the air it feels in it's paws, similar to a skydiver using arms and legs to control attitude while at terminal velocity.

Once at terminal velocity, you don't get the sensation of free fall acceleration in your internal organs, because you're no longer accelerating, and the full force of gravity is once again pulling all your internal organs downwards since you're at constant velocity.

Other factors why some cats survive large falls (I don't know how rare survival is), is their terminal velocity is much lower than a humans, and their bone structure may be more flexible while their smaller internal organs may be more resistant to fluid shock.

Rather than dropping a cat, one of those skydiving like chambers that generate a high speed upwards flow of air inside a padded cylindrical tower could be used to see the cat's reaction.

 

[himanshu2004@]

Once at terminal velocity, you don't get the sensation of free fall acceleration in your internal organs, because you're no longer accelerating, and the full force of gravity is once again pulling all your internal organs downwards since you're at constant velocity.

I agree with most of your post, but just a minor correction - the downward push felt has nothing to do with internal organs versus non-internal organs. When on the earth, the downward (or upward depending on how you look at it) force is felt by the all the organs - the body feels this downward tendency to push into the feet, the abdomen into the hips and pelvis, and the head into the neck, etc - ultimately the entire musculo-skeletal structure feels it depending on how were are resting our weight. And hence in free fall, where this effect is absent, the difference would be felt pretty much all through the body.

You probably realize this anyway, but this notion of "internal" organs creates a confusion, as was apparent from some of the posts, where one compares the body's exterior with a non-intertial frame like an accelerating car, and hence assumes that the "internal" things feel inertial forces (relative to the non-inertial frame).

 

[harrylin]

@harrylin
Sorry I should have clarified that the "righting reflex" bit I did understand. However, the physics of falling cats involves both the righting reflex and them relaxing and spreading out more on reaching terminal velocity, which further reduces terminal velocity as result of increased air drag.

OK - do you have evidence of that?

My doubts, which have now been resolved, were regarding how they feel they have stopped accelerating upon reaching terminal velocity, because one doesn't "feel" acceleration due to free fall in gravity the same way one "feels" acceleration inside say an accelerating car (which is a non-inertial frame, unlike free fall). More specifically, even though I understood that free fall would feel different from the familiar feeling of being on the ground, it took me a little time to realize that that gradually by the time of reaching terminal velocity the cat would almost "feel" similar again to what it is used to feeling on the Earth (in terms of it feeling an upward trust from below, which is absent in ideal free fall)

That also sounds wrong to me: why would a cat wait until it stops accelerating for spreading out its legs? It makes much more sense to me if a cat spreads out its legs when it feels a strong air flow. If I were a cat, that's how I imagine I'd react.

Cheers,
Harald

 

[himanshu2004@]

@Harrylin
I don't have any personally collected evidence, but you could see the link posted earlier in the thread and this phenomenon seems mentioned in several places including texts of some repute.
Regarding what you don't understand, I cannot provide any new explanation other than what has already been provided in this thread (in fact this entire thread has been about this). So maybe go through it again, and see if it makes sense. Just to point out, the cat doesn't spread out it legs like making them horizontal or something, but they become more spread out relative to when the cat is uncomfortable and stiffer. The link I spoke of also a picture of that.

 

[BruceW]

You probably realize this anyway, but this notion of "internal" organs creates a confusion, as was apparent from some of the posts, where one compares the body's exterior with a non-intertial frame like an accelerating car, and hence assumes that the "internal" things feel inertial forces (relative to the non-inertial frame).

This is what happens when the body exterior is subject to some contact force from outside. So the comparison is good, (unless the force is gravity, which acts on everything).

 

[himanshu2004@]

@Bruce
Yes that's exactly what I was trying to clarify that acceleration due to gravity is different from accelerating in non-inertial frames, such as cars that we are used to thinking about whenever we think "acceleration". In fact, being on the Earth (and hence NOT accelerating due the Earth's upward thrust) is like being in a non inertial frame which is accelerating upwards with an acceleration g.

 

[harrylin]

@Harrylin
I don't have any personally collected evidence, but you could see the link posted earlier in the thread and this phenomenon seems mentioned in several places including texts of some repute.
Regarding what you don't understand, I cannot provide any new explanation other than what has already been provided in this thread (in fact this entire thread has been about this). So maybe go through it again, and see if it makes sense. Just to point out, the cat doesn't spread out it legs like making them horizontal or something, but they become more spread out relative to when the cat is uncomfortable and stiffer. The link I spoke of also a picture of that.

Thanks I'm perfectly happy with my explanation of the facts (not the suggestions) that I have seen presented.

 

[mender]

I am pretty sure that if the metal box is air-tight, the balloon would fall exactly as the same rate as the box.

Only if the balloon has exactly neutral buoyancy.

 

[himanshu2004@]

Only if the balloon has exactly neutral buoyancy.

No, whatever equilibrium position the balloon was in before the box is dropped, it would more or less continue to stay there, neutral buoyancy or not. (Of course one cannot really talk of an equilibrium position of the balloon during the box's free fall, because that's like being in zero gravity.)
So if the balloon was filled with a lighter-than-air substance and was resting against the roof of the box, it would continue to stay there during the box's free fall drop. And if the balloon was filled with air, water, stones, etc and was resting against the floor of the box, it would continue to stay there.
Note that any effects of buoyancy wouldn't be applicable during the free fall of the box, because there is no concept of weight in free fall.
(For simplicity, I have ignored disturbances due to redistribution in the air's density from being higher near the bottom of the box initially to changing towards uniformity during free fall)

If there is an error in this analysis, please point it out; my Physics is a little scratchy from many years of staying away, but I intend to fix that by re-engaging.

The original poster's thought experiment, and incorrect conclusion, for context:

A crude analogy, imagine an air filled balloon sitting on the floor of a metal box, attached to the side by a length elastic. You suddenly drop the box. The balloon does not fall at the same rate as the box and is likely to hit the roof of the box. It is "left behind" for a short while. It's the same effect in your body.

Your whole body and everything in it may be subject to the same force from gravity, but it doesn't mean it will fall at the same rate whilst in a medium.

 

[BruceW]

Good explanation. Am I right in thinking that astronauts upon re-entry will initially be weightless, then when the spaceship starts to hit the atmosphere, the astronauts will begin to feel some contact with the floor again, and then when the spaceship reaches terminal velocity, the astronauts will 'feel' just like we do sitting on earth. (apart from the fact that they will get very hot).

 

[mender]

Note that any effects of buoyancy wouldn't be applicable during the free fall of the box, because there is no concept of weight in free fall.
(For simplicity, I have ignored disturbances due to redistribution in the air's density from being higher near the bottom of the box initially to changing towards uniformity during free fall)

I was considering the removal of an acceleration field to have similar but opposite consequences as the application because of that effect. When a vehicle with helium balloons in it accelerates, the balloons reposition themselves in the air in the vehicle, responding to the change in air density gradient. For the analogy, that means that unless the balloons are exactly neutrally buoyant, their acceleration rate will differ from the box but only during the redistribution phase.

So we're talking about the same thing, but I was specifying that effect rather than ignoring it. Other than that, there would be no difference when the acceleration field that is acting on all the objects uniformly is removed.

ETA: And now that I think about it further, it appears that you were accounting for that effect as well when referring to the lack of buoyancy effects when in free fall, in that all balloons become "neutrally buoyant" when in free fall. Well thought out and well done! You are correct on all points!

Thanks for the discussion!