[Tom Bishop]

Snipped for post brevity

Oh, awesome. So the Quora guy agrees completely as he gives 0.1 m/s^2 at the low end, and we're talking about a speed around 20% of that. The second source you link is very clear that it's talking about *vibrating* acceleration, which is not what's being discussed. Even if it were, it suggests our 0.02 m/s^2 is on the very lowest edge of human perception. Both of your sources appear to be in agreement that we should not be able to feel the acceleration due to the spin of the Earth. Even 'best case' suggests it would be likely difficult to do so, assuming a set of circumstances that aren't reality. Thank you for presenting a rather strong case against your own premise.

Ranges between 0.01 m/s^2 and 0.0221 m/s^2 are in the "probable perception" to "clear perception" range. Yet no one has perceived the rotation of the earth. Why?

The author of the quora article who wrote a thesis on the subject told us to look up vibrational perception. It makes sense. We are detecting different accelerations depending on which direction we face, and can go from minus to plus depending on one's position. Yet again, however, no one has felt this acceleration.

Those ranges are for something vibrating at speeds of 2-20Hz, and I would wager the low vibration end is towards the higher Hz end. He specifically calls out an elevator too, noting the lowest was around 0.1 m/s^2. The elevator is much closer to normal conditions on Earth.

But sure, lets go with just spinning, and we'll go with the best case scenario, looking for 0.0221 m/s^2 is detectable. But wait, we *also* have to account for the 'noise' we'll be making as we spin. That will be far more noticeable most likely. So if we go with our 80kg guy from before. The average length from hip to hip is about 3.6m. We'll cut down to 1.2m radius and 40kg. I think that should give us a rough sort of midpoint, but I'll run a few others too for fun. That gives us a speed of spin of roughly 15 m/s^2 for our 40k, generating centripetal force equal to 7500 Newtons. That's about 764 kg m/s^2 of force. Not sure anyone is gonna notice an extra 0.0221. Well let's see what we can do to get this a bit more favorable, shall we?

Hrmm, the lowest I'm getting, using the shortest person to have lived, gives me about 23.2 kg m/s^2. For whom I was being somewhat generous as well imo. Radius of 0.30m (about his 'center' using a similar method as above), gives us a velocity of 3.7 m/s^2, and a weight of 5kg. I'm not seeing what part of you is supposed to have felt this acceleration Tom, especially not feeling it over simply the force generated by spinning yourself around. Feel free to check my math if you like, I encourage it in fact. But your hypothesis that we should be able to feel it by spinning is looking dead in the water again.

People don't just rotate on their own power. People spin in cars, aircraft, in freefall. No one has detected this vibration as they are turned in orientation. If this were a thing, we would know about it.

[Curious Squirrel]

Snipped for post brevity

Oh, awesome. So the Quora guy agrees completely as he gives 0.1 m/s^2 at the low end, and we're talking about a speed around 20% of that. The second source you link is very clear that it's talking about *vibrating* acceleration, which is not what's being discussed. Even if it were, it suggests our 0.02 m/s^2 is on the very lowest edge of human perception. Both of your sources appear to be in agreement that we should not be able to feel the acceleration due to the spin of the Earth. Even 'best case' suggests it would be likely difficult to do so, assuming a set of circumstances that aren't reality. Thank you for presenting a rather strong case against your own premise.

Ranges between 0.01 m/s^2 and 0.0221 m/s^2 are in the "probable perception" to "clear perception" range. Yet no one has perceived the rotation of the earth. Why?

The author of the quora article who wrote a thesis on the subject told us to look up vibrational perception. It makes sense. We are detecting different accelerations depending on which direction we face, and can go from minus to plus depending on one's position. Yet again, however, no one has felt this acceleration.

Those ranges are for something vibrating at speeds of 2-20Hz, and I would wager the low vibration end is towards the higher Hz end. He specifically calls out an elevator too, noting the lowest was around 0.1 m/s^2. The elevator is much closer to normal conditions on Earth.

But sure, lets go with just spinning, and we'll go with the best case scenario, looking for 0.0221 m/s^2 is detectable. But wait, we *also* have to account for the 'noise' we'll be making as we spin. That will be far more noticeable most likely. So if we go with our 80kg guy from before. The average length from hip to hip is about 3.6m. We'll cut down to 1.2m radius and 40kg. I think that should give us a rough sort of midpoint, but I'll run a few others too for fun. That gives us a speed of spin of roughly 15 m/s^2 for our 40k, generating centripetal force equal to 7500 Newtons. That's about 764 kg m/s^2 of force. Not sure anyone is gonna notice an extra 0.0221. Well let's see what we can do to get this a bit more favorable, shall we?

Hrmm, the lowest I'm getting, using the shortest person to have lived, gives me about 23.2 kg m/s^2. For whom I was being somewhat generous as well imo. Radius of 0.30m (about his 'center' using a similar method as above), gives us a velocity of 3.7 m/s^2, and a weight of 5kg. I'm not seeing what part of you is supposed to have felt this acceleration Tom, especially not feeling it over simply the force generated by spinning yourself around. Feel free to check my math if you like, I encourage it in fact. But your hypothesis that we should be able to feel it by spinning is looking dead in the water again.

People don't just rotate on their own power. People spin in cars, aircraft, in freefall. No one has detected this vibration as they are turned in orientation. If this were a thing, we would know about it.

So you have no actual refutation, simply repeating "We would know" over and over. I just laid out the math for why we *wouldn't* notice this 'vibration' due to the Earth's rotation. It's incredibly tiny compared to the forces simply spinning would have upon your body, regardless of just *how* you're spinning. If I spin you at 20Hz you'll experience even more force from that motion. You have yet to provide a shred of credible evidence that we should be able to feel the 0.01-0.0221 m/s^2 of additional acceleration from the spinning of the Earth, compared to the accelerations we would be feeling from other sources in our attempt to sense this one. 'We would know' is neither empirical, nor zetetic. Prove it. All you've provided so far shows we just might be able to sense it under the right circumstances. But every circumstance you've suggested to attempt to sense it results in far greater noise than a human can possibly ignore. So far all I've gotten is even more that there's no reason to think we could detect the spinning/rotation of the Earth on our own.

[HorstFue]

But, and this is the thing you keep ignoring, MY MATHS IS WRONG. It’s wrong for the same reason the maths in the video is wrong. I have assumed that you are going at 460m/s in a STRAIGHT LINE in one direction and, over 12 hours you change velocity so that you are now going at 460m/s in the opposite direction. That is the logic of the video.

That's the error in the video, it only shows acceleration in "x-direction". What about the "y-direction"? On the 6am and 6pm positions, you would have to place the same arrows as on 12am and 12pm, but in perpendicular direction. This guy, who produced the video, suppressed this acceleration. If you now combine these vectors - decreasing with a cos-function, increasing with a sin-function - the resulting vector would be radial from (or to) earth center.
You could have it easier, if you consider the setup as this what it is: (sorry I don't know the exact term in English) a steady circular motion: The only force or acceleration produced by this motion is centripetal/centrifugal force:
a) radial to the center
b) constant

So at the equator the force is anti-parallel to gravity. The only thing you could measure - not notice - is that things at the equator are a bit less heavy, and this doesn't change in the course of a day (constant!). And most notable there's no additional acceleration in the direction along the curved path.

[Tom Bishop]

So you have no actual refutation, simply repeating "We would know" over and over. I just laid out the math for why we *wouldn't* notice this 'vibration' due to the Earth's rotation. It's incredibly tiny compared to the forces simply spinning would have upon your body, regardless of just *how* you're spinning. If I spin you at 20Hz you'll experience even more force from that motion. You have yet to provide a shred of credible evidence that we should be able to feel the 0.01-0.0221 m/s^2 of additional acceleration from the spinning of the Earth, compared to the accelerations we would be feeling from other sources in our attempt to sense this one. 'We would know' is neither empirical, nor zetetic. Prove it. All you've provided so far shows we just might be able to sense it under the right circumstances. But every circumstance you've suggested to attempt to sense it results in far greater noise than a human can possibly ignore. So far all I've gotten is even more that there's no reason to think we could detect the spinning/rotation of the Earth on our own.

There was already plenty of noise in the experiments in which it was determined that people can feel 0.01+ m/s^2. Bodily movements, attention, etc. Yet 0.01+ m/s^2 was still set as the threshold for human perception.

You are the one who needs to prove that there is some mysterious noise that prevents one from detecting such acceleration. You are claiming that if we are turning in one direction, that there is too much noise to detect vibration. What noise? Are you claiming that the human body's ability to detect vibration from any and all directions turns off if one is turning? Are you claiming that when we turn, that the human body exactly cancels out any and all vibrations from all directions?

My part is already done. You are the one tying to bring in mysterious variables here, in increasingly desperate tactics to claim that it is all too noisy to detect. You are the one who has no actual refutation, instead resting your argument on mysterious noise. Substantiate your mysterious variables.

[Curious Squirrel]

So you have no actual refutation, simply repeating "We would know" over and over. I just laid out the math for why we *wouldn't* notice this 'vibration' due to the Earth's rotation. It's incredibly tiny compared to the forces simply spinning would have upon your body, regardless of just *how* you're spinning. If I spin you at 20Hz you'll experience even more force from that motion. You have yet to provide a shred of credible evidence that we should be able to feel the 0.01-0.0221 m/s^2 of additional acceleration from the spinning of the Earth, compared to the accelerations we would be feeling from other sources in our attempt to sense this one. 'We would know' is neither empirical, nor zetetic. Prove it. All you've provided so far shows we just might be able to sense it under the right circumstances. But every circumstance you've suggested to attempt to sense it results in far greater noise than a human can possibly ignore. So far all I've gotten is even more that there's no reason to think we could detect the spinning/rotation of the Earth on our own.

There was already plenty of noise in the experiments in which it was determined that people can feel 0.01+ m/s^2. Bodily movements, attention, etc. Yet 0.01+ m/s^2 was still set as the threshold for human perception.

You are the one who needs to prove that there is some mysterious noise that prevents one from detecting such acceleration. You are claiming that if we are turning in one direction, that there is too much noise to detect vibration. What noise? Are you claiming that the human body's ability to detect vibration from any and all directions turns off if one is turning? Are you claiming that when we turn, that the human body exactly cancels out any and all vibrations from all directions?

My part is already done. You are the one tying to bring in mysterious variables here, in increasingly desperate tactics to claim that it is all too noisy to detect. You are the one who has no actual refutation, instead resting your argument on mysterious noise. Substantiate your mysterious variables.

I've shown you repeatedly where the noise comes from. The centripetal force generated by your own body when spun about an axis at 2+Hz, which is greater than 100x the acceleration difference we're supposed to be looking for. The sources/studies show we can detect 0.02 m/s^2 of vibrational acceleration. But that in no way shows we can tell the difference between 23.18 m/s^2 and 23.22 m/s^2, which would be the maximum percentage difference between front and back when spun at 2Hz. I've substantiated these variables in an earlier post and requested you to check my math. Or explain why you disagree with my necessary assumptions. You've done neither, suggesting you feel they are fine. Substantiate your claim that we can detect/feel that difference, or explain where I've erred in my math. Or I guess keep deliberately missing the point I suppose.

[Mysfit]

There was already plenty of noise in the experiments in which it was determined that people can feel 0.01+ m/s^2. Bodily movements, attention, etc. Yet 0.01+ m/s^2 was still set as the threshold for human perception.

I checked, clothing is only mentioned in a test-safety sense in the human vibration book.
So, I will say my mysterious noise will be clothing. We all get one.
It's most relevant as it moves when you rotate. Literally making noise.

[stack]

My part is already done. You are the one tying to bring in mysterious variables here, in increasingly desperate tactics to claim that it is all too noisy to detect. You are the one who has no actual refutation, instead resting your argument on mysterious noise. Substantiate your mysterious variables.

I think Curious already touched on this a while back. But the data you're quoting from the "Handbook of Human Vibration" is from Chapter 6, “Perception of Whole-body Vibration and the Assessment of Vibration in Buildings". Is that really an appropriate comparison to earth rotation? Building vibration? Seems like an equally mysterious substantiation. Shouldn't you actually be quote mining from Chapter 7 "Motion Sickness", maybe specifically 7.4 "Effects of Rotational Motion"?

[AATW]

But, and this is the thing you keep ignoring, MY MATHS IS WRONG. It’s wrong for the same reason the maths in the video is wrong. I have assumed that you are going at 460m/s in a STRAIGHT LINE in one direction and, over 12 hours you change velocity so that you are now going at 460m/s in the opposite direction. That is the logic of the video.

That's the error in the video, it only shows acceleration in "x-direction". What about the "y-direction"? On the 6am and 6pm positions, you would have to place the same arrows as on 12am and 12pm, but in perpendicular direction. This guy, who produced the video, suppressed this acceleration. If you now combine these vectors - decreasing with a cos-function, increasing with a sin-function - the resulting vector would be radial from (or to) earth center.
You could have it easier, if you consider the setup as this what it is: (sorry I don't know the exact term in English) a steady circular motion: The only force or acceleration produced by this motion is centripetal/centrifugal force:
a) radial to the center
b) constant

So at the equator the force is anti-parallel to gravity. The only thing you could measure - not notice - is that things at the equator are a bit less heavy, and this doesn't change in the course of a day (constant!). And most notable there's no additional acceleration in the direction along the curved path.

This is my understanding too, I believe the force because of the earth's rotation works in a direction opposite to gravity.
So you are 0.3% lighter at the equator than at the poles. Enough to measure, not enough to notice.
I don't believe there is any sideways force but I'm willing to be corrected if I've got that wrong.

[Tom Bishop]

I've shown you repeatedly where the noise comes from. The centripetal force generated by your own body when spun about an axis a 2+Hz, which is greater than 100x the acceleration difference we're supposed to be looking for. The sources/studies show we can detect 0.02 m/s^2 of vibrational acceleration. But that in no way shows we can tell the difference between 23.18 m/s^2 and 23.22 m/s^2, which would be the minimum percentage difference between front and back when spun at 2Hz.

By this logic it should be impossible to tell the difference between 9.8 m/s^2 and 9.8 m/s^2 +/- 0.02 m/s^2. Is that correct?

Yet we previously saw that the first example used in the quora link was with sensing small vibrations in an elevator, which travels in a vertical direction.

We read the following:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189668/

Although studies have shown that the human perception threshold to vibration varies slightly with age, position of the body, body region, and axis of vibration,10,22 the median human vibration perception threshold is approximately 0.01 m/s^2 for vertical vibration

How is vertical vibration of that small magnitude detected if the body is already traveling vertically at 9.8 m/s^2?

This shows the premise, that additional accelerations cannot be felt, to be faulty.

[stack]

I've shown you repeatedly where the noise comes from. The centripetal force generated by your own body when spun about an axis a 2+Hz, which is greater than 100x the acceleration difference we're supposed to be looking for. The sources/studies show we can detect 0.02 m/s^2 of vibrational acceleration. But that in no way shows we can tell the difference between 23.18 m/s^2 and 23.22 m/s^2, which would be the minimum percentage difference between front and back when spun at 2Hz.

By this logic it should be impossible to tell the difference between 9.8 m/s^2 and 9.8 m/s^2 +/- 0.02 m/s^2. Is that correct?

Yet we previously saw that the first example used in the quora link was with sensing small vibrations in an elevator, which travels in a vertical direction.

We read the following:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189668/

Although studies have shown that the human perception threshold to vibration varies slightly with age, position of the body, body region, and axis of vibration,10,22 the median human vibration perception threshold is approximately 0.01 m/s^2 for vertical vibration

How is vertical vibration of that small magnitude detected if the body is already traveling vertically at 9.8 m/s^2?

This shows the premise, that additional accelerations cannot be felt, to be faulty.

This is a study about vibrations from nearby construction equipment. As well, humans are less affected than rats.

"Vibration caused by various items of construction equipment at 3 ft from the cage were evaluated relative to the RFR and SFR of humans, rats, and mice in 3 anatomic locations. In addition, the vibration levels in the RFR and SFR that resulted from the use of a large jackhammer and were measured at various locations and distances in the facility and evaluated in terms of humans, rats, and mice in 3 anatomic locations. Taken together, the data indicate that a given vibration source generates vibration in frequency ranges that are more likely to affect rats and mice as compared with humans."

As well, you left off a part of the sentence you quoted.

"...the median human vibration perception threshold is approximately 0.01 m/s2 for vertical vibration (the vibration measured in the current study) between 0 and 63 Hz."

As in the vibration from construction equipment. How is this relative to earth rotation?

[Tom Bishop]

I've shown you repeatedly where the noise comes from. The centripetal force generated by your own body when spun about an axis a 2+Hz, which is greater than 100x the acceleration difference we're supposed to be looking for. The sources/studies show we can detect 0.02 m/s^2 of vibrational acceleration. But that in no way shows we can tell the difference between 23.18 m/s^2 and 23.22 m/s^2, which would be the minimum percentage difference between front and back when spun at 2Hz.

By this logic it should be impossible to tell the difference between 9.8 m/s^2 and 9.8 m/s^2 +/- 0.02 m/s^2. Is that correct?

Yet we previously saw that the first example used in the quora link was with sensing small vibrations in an elevator, which travels in a vertical direction.

We read the following:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189668/

Although studies have shown that the human perception threshold to vibration varies slightly with age, position of the body, body region, and axis of vibration,10,22 the median human vibration perception threshold is approximately 0.01 m/s^2 for vertical vibration

How is vertical vibration of that small magnitude detected if the body is already traveling vertically at 9.8 m/s^2?

This shows the premise, that additional accelerations cannot be felt, to be faulty.

This is a study about vibrations from nearby construction equipment. As well, humans are less affected than rats.

"Vibration caused by various items of construction equipment at 3 ft from the cage were evaluated relative to the RFR and SFR of humans, rats, and mice in 3 anatomic locations. In addition, the vibration levels in the RFR and SFR that resulted from the use of a large jackhammer and were measured at various locations and distances in the facility and evaluated in terms of humans, rats, and mice in 3 anatomic locations. Taken together, the data indicate that a given vibration source generates vibration in frequency ranges that are more likely to affect rats and mice as compared with humans."

As well, you left off a part of the sentence you quoted.

"...the median human vibration perception threshold is approximately 0.01 m/s2 for vertical vibration (the vibration measured in the current study) between 0 and 63 Hz."

As in the vibration from construction equipment. How is this relative to earth rotation?

The same perception threshold of 0.01 m/s^2 is given in the previous source I gave. The threshold is 0.01 m/s^2 is where people feel vibration. It doesn't matter if it comes from a jackhammer. That's the threshold.

[stack]

The same perception threshold of 0.01 m/s^2 is given in the previous source I gave. The threshold is 0.01 m/s^2 is where people feel vibration. It doesn't matter if it comes from a jackhammer. That's the threshold.

Is 'vibration' perception the same as "a spinning earth would add additional pull straight down towards its surface" perception?

[Tom Bishop]

The same perception threshold of 0.01 m/s^2 is given in the previous source I gave. The threshold is 0.01 m/s^2 is where people feel vibration. It doesn't matter if it comes from a jackhammer. That's the threshold.

Is 'vibration' perception the same as "a spinning earth would add additional pull straight down towards its surface" perception?

The importance of vibration perception in this subject of sensing acceleration was described in the quora link.

[stack]

The same perception threshold of 0.01 m/s^2 is given in the previous source I gave. The threshold is 0.01 m/s^2 is where people feel vibration. It doesn't matter if it comes from a jackhammer. That's the threshold.

Is 'vibration' perception the same as "a spinning earth would add additional pull straight down towards its surface" perception?

The importance of vibration perception in this subject of sensing acceleration was described in the quora link.

Understood, but:

A) I wouldn't consider a Quora response to a question a substantiation of your position.
B) The Quora author 'speculates' and states: "Often it is the "jerk" that we notice in a situation like this (rather than the constant rate of acceleration itself)." When we talk about earth rotation, we are not talking about starting and stopping, but 'constant rate'.
C) 'vibration', at least to me, is not the same as a 'pull straight down towards its surface'.  A vibration is, back and forth, up and down, side to side and everywhere in between. The other a pull, straight down to the surface. Seems like apples and oranges.

[AATW]

The acceleration of an object moving in a circle can be determined by v2/r

https://www.physicsclassroom.com/class/circles/Lesson-1/Mathematics-of-Circular-Motion

v = 460m/s (velocity of earth's rotation at the equator)
r = 6371000 (radius of earth)

460x460/6371000 = 0.033213m/s/s

So that is the acceleration due to the rotation of the earth and that accelaration is directed inwards. That is counter-intuitive because you feel like you're being thrown outwards but

"The sensation of an outward force and an outward acceleration is a false sensation. There is no physical object capable of pushing you outwards. You are merely experiencing the tendency of your body to continue in its path tangent to the circular path along which the car is turning. You are once more left with the false feeling of being pushed in a direction that is opposite your acceleration."

https://www.physicsclassroom.com/class/circles/Lesson-1/The-Centripetal-Force-Requirement

So unless I've understood anything wrong, there is no sideways acceleration or force that you'd feel.

[Curious Squirrel]

I've shown you repeatedly where the noise comes from. The centripetal force generated by your own body when spun about an axis a 2+Hz, which is greater than 100x the acceleration difference we're supposed to be looking for. The sources/studies show we can detect 0.02 m/s^2 of vibrational acceleration. But that in no way shows we can tell the difference between 23.18 m/s^2 and 23.22 m/s^2, which would be the minimum percentage difference between front and back when spun at 2Hz.

By this logic it should be impossible to tell the difference between 9.8 m/s^2 and 9.8 m/s^2 +/- 0.02 m/s^2. Is that correct?

Yet we previously saw that the first example used in the quora link was with sensing small vibrations in an elevator, which travels in a vertical direction.

We read the following:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189668/

Although studies have shown that the human perception threshold to vibration varies slightly with age, position of the body, body region, and axis of vibration,10,22 the median human vibration perception threshold is approximately 0.01 m/s^2 for vertical vibration

How is vertical vibration of that small magnitude detected if the body is already traveling vertically at 9.8 m/s^2?

This shows the premise, that additional accelerations cannot be felt, to be faulty.

No, this shows there is a higher threshold than the 0.01-0.02 or so of the other study, when dealing with a difference in larger accelerations, rather than simply sensing it. The Quora link stated that sensing an elevator movement had a lower bounds of 0.1 m/s^2. Significantly higher than anything we've determined for what may or may not exist for the rotation of the Earth. I would argue this would be compounded depending on speed, but that's largely irrelevant to the fact his statements still fully support we should be unable to tell the difference between 9.8 m/s^2 and 9.8 m/s^2 +/- 0.02 m/s^2, or whatever speeds we might be discussing. We can sense vibrations as tiny as 0.01 m/s^2. That doesn't mean we can tell the difference between 0.03 and 0.04. Or anything else for that matter.

[Tom Bishop]

The same perception threshold of 0.01 m/s^2 is given in the previous source I gave. The threshold is 0.01 m/s^2 is where people feel vibration. It doesn't matter if it comes from a jackhammer. That's the threshold.

Is 'vibration' perception the same as "a spinning earth would add additional pull straight down towards its surface" perception?

The importance of vibration perception in this subject of sensing acceleration was described in the quora link.

Understood, but:

A) I wouldn't consider a Quora response to a question a substantiation of your position.
B) The Quora author 'speculates' and states: "Often it is the "jerk" that we notice in a situation like this (rather than the constant rate of acceleration itself)." When we talk about earth rotation, we are not talking about starting and stopping, but 'constant rate'.
C) 'vibration', at least to me, is not the same as a 'pull straight down towards its surface'.  A vibration is, back and forth, up and down, side to side and everywhere in between. The other a pull, straight down to the surface. Seems like apples and oranges.

Detecting a change in acceleration is a detection of vibration upon your body. Of course it is directly relevant. Seeing as the author of that article wrote a thesis on the matter, I would characterize the article as more than 'speculation'.

[AATW]

The acceleration because of the rotation of the earth is vertical, not horizontal. There is no sideways pull on us because of it so far as I can gather from the links above about the physics of circular motion.

[garygreen]

it doesn't make any sense to compare a vibration to a constant centrifugal force.

a vibration is a change in acceleration.  the centrifugal acceleration for a person standing on the earth's surface is constant.  those are not comparable at all.

[Tom Bishop]

The acceleration because of the rotation of the earth is vertical, not horizontal. There is no sideways pull on us because of it so far as I can gather from the links above about the physics of circular motion.

https://www.physicsclassroom.com/class/circles/Lesson-1/Acceleration

And since velocity is a vector that has both magnitude and direction, a change in either the magnitude or the direction constitutes a change in the velocity. For this reason, it can be safely concluded that an object moving in a circle at constant speed is indeed accelerating.

...



Direction of the Acceleration Vector

Note in the diagram above that there is a velocity change for an object moving in a circle with a constant speed. A careful inspection of the velocity change vector in the above diagram shows that it points down and to the left. At the midpoint along the arc connecting points A and B, the velocity change is directed towards point C - the center of the circle. The acceleration of the object is dependent upon this velocity change and is in the same direction as this velocity change. The acceleration of the object is in the same direction as the velocity change vector

it doesn't make any sense to compare a vibration to a constant centrifugal force.

a vibration is a change in acceleration.  the centrifugal acceleration for a person standing on the earth's surface is constant.  those are not comparable at all.

If you are standing with the left side of your body facing the acceleration and turn in a complete circle you would be experiencing a change of 200% of the acceleration on the left side of your body when you travel 180 degrees, and then another 200% as you return to your spot. The side of your body is being pulled and pushed in different directions.