[David Cooper]

That stubbornness of yours doesn´t deserve further explanations, but I´ll continue for the sake of the interest of others ...

There are two stubborn people here: one is stubbornly right and the other is stubbornly wrong.

Your investigations, if any, are quite the opposite to Sherlock Holmes´s … He would never say the first found suspect was the murderer, without a thorough analysis of all available details !

If Holmes was analysing this, he would tackle the task in a rational way, as I do.

1) physical reality: the centripetal force doesn´t actually disappear ,

The force is completely gone - the rope is slack. What sense does it make to claim that a force is still there when it's no longer present?

2) as logic (?) conclusion: one thing is “correlation” and quite another “causation” (also “ basics of basics” in its realm)

That is precisely your problem - you are being misled by correlation and cannot determine the actual causation. In the case of a ball on the end of the string, the movement of the ball causes the force to be generated in the string. In the case of an object orbiting a planet, the force is not caused by the movement of the object, and this shows up when we stop the object moving and then watch it fall down onto the planet as the force continues to act.

[David Cooper]

...if the hammer an athlete is going to throw were suddenly stopped by a physical obstacle, since that very moment centripetal force (previously changing the direction of the hammer movement), would change to accelerate linearly the weight and the wire "inwards", and even the athlete would move back and fall down ... Clear prove that the centripetal force was being exerted by the athlete on inner extreme of the wire, transmitted section by section through the wire, and finally to the weight through outer extreme of the wire !! 

In the case of a ball going round on a string attached to a pole which is turn anchored to the Earth, if the ball is stopped (perhaps by hitting the same bat that set it moving in the first place), 99.99% of the force in the string may disappear, the only remnant being caused by a little flexing of the pole (which will have been pulled towards the ball throughout rather than away, which is quite different from the case of the hammer-thrower). A new force will then be generated in the string as the ball falls, again generated by the movement of the ball which tries to take it where the string can't let it go.

Your hammer-throwing case is more like two balls going round and round on opposite ends of a string. To eliminate the force in an instant, you'd have to stop both of them moving simultaneously because the movement of both is generating the force, although just stopping one of them would substantially reduce the force in the string, and if you were to record the transmission of the change in force in the string by putting a series of detectors along it, you would find that the change starts at the end where the stopped ball is and it races from there to the other end, probably at the speed of sound in the string. That movement of change reveals the route of causation, and it's the very opposite of the one you've asserted.

[rmolnav]

As I´ve already said several times, I´m afraid It´s useless to carry on discussing with you …

In the case of a ball going round on a string attached to a pole which is turn anchored to the Earth, if the ball is stopped (perhaps by hitting the same bat that set it moving in the first place)

It would be quite a spectacle to see you hitting a ball hanging from a string and pole tens of times (or hundreds) trying to make it get and follow a horizontal circular path, without any resting interval (otherwise the ball would descend).
In any case, if somehow we could made the ball properly rotate that way, the movement of the ball is logically necessary for its rotation: no centripetal force could make a null speed vector change direction !! But that doesn´t mean the movement “causes” the centripetal force !!
You ignore (or forget, or don´t understand and handle wrongly…) other details of the scenario such as the concept of inertia, the action and reaction principle, that to have a string tight two opposite forces are required, etc, etc.
A prove of that is:

... a little flexing of the pole (which will have been pulled towards the ball throughout rather than away,

Don´t you realize that, if the pole has "been pulled towards the ball”(as you correctly say), that pull cannot be a “centripetal” force caused by the ball movement, because it has an outward direction ??
I would call it centrifugal force, in a singular flavor of the concept, because in that case we could say it is an “active” force (action), and the centripetal one is a “reactive” force (reaction), when usually the opposite happens: centrifugal force is an inertial reaction to an “active” centripetal force …
I´m afraid that, as you consider centripetal force a “grey” area, adding those details could be a “black” area for you …
In any case, I´ll carry on for the sake of the interest of others:
Hitting a ball produces a transference of momentum, always through forces. At the very initial instant some deformations (of the ball and the bat) occur, what produces opposite pushes on each other, which then change both speed vectors … The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite of what you say !!

[David Cooper]

As I´ve already said several times, I´m afraid It´s useless to carry on discussing with you …

That's because I'm right and you're wrong, but you're determined that wrong is right.

In the case of a ball going round on a string attached to a pole which is turn anchored to the Earth, if the ball is stopped (perhaps by hitting the same bat that set it moving in the first place)

It would be quite a spectacle to see you hitting a ball hanging from a string and pole tens of times (or hundreds) trying to make it get and follow a horizontal circular path, without any resting interval (otherwise the ball would descend).

You specialise in making errors and irrelevant objections. I don't know if you've ever heard of Swingball which has a ball on a string that you hit with a bat, the other end being attached to the top of a pole, but the high speed of the ball takes it round and round in circles very nicely, and if you let the ball hit the bat while the bat's moving away from it at the right speed you can take all the speed out of the ball (at which point it will accelerate (from stationary) downwards and swing in towards the pole, though this part of the action is a side issue  we're only really interested in what happens when the ball stops going round horizontally). The small amount of descent on each circuit due to gravity is also something you should be able to ignore when focusing on the physics in question, but you seem incapable of tuning out all the noise, and that's likely why you struggle so much to get to a pure understanding of any individual part of any mechanism.

In any case, if somehow we could made the ball properly rotate that way, the movement of the ball is logically necessary for its rotation: no centripetal force could make a null speed vector change direction !! But that doesn´t mean the movement “causes” the centripetal force !!

Of course the movement causes the force. Stop the movement and the force disappears. Start the movement and the force returns. The force doesn't cause the movement, but is caused by the movement. Each change from movement to non-movement or the opposite leads to a change in force in the string starting at the ball end and transmitting to the pole end at the speed of sound in the string (and you could record that by putting sensors in the string to monitor its local tension - though note that this is just the small initial increase in tension and not the one that ramps it up by many magnitudes when the centripetal force kicks in). That is the course the causality takes.

You have the idea that forces cause movement and that movement can't cause force, but both are possible and both are common. A force can start something moving, and the movement can then lead to a different force being generated. In the case of a ball on a string going round in circles, the first force sets the ball moving, that movement then generates the centripetal force in the string, the centripetal force then modifies the movement of the ball, changing the direction of its travel.

You ignore (or forget, or don´t understand and handle wrongly…) other details of the scenario such as the concept of inertia, the action and reaction principle, that to have a string tight two opposite forces are required, etc, etc.

There are plenty of ways to apply transformations to my description of events to turn it into other correct wordings, but the existence of other correct wordings does not make my wording wrong. Most importantly though, my wording has causation working in the right direction - opposite to the incorrect direction that you assert for it. You want the centripetal force to cause the movement of the ball (even though all it does is modify the movement of the ball).

A prove of that is:

... a little flexing of the pole (which will have been pulled towards the ball throughout rather than away,

Don´t you realize that, if the pole has "been pulled towards the ball”(as you correctly say), that pull cannot be a “centripetal” force caused by the ball movement, because it has an outward direction ??

Again you blind yourself with side issues. None of that negates the fact that centripetal force is acting in the string and pulling on the ball, and when the ball is stopped, that centripetal force disappears 100% as a result of the movement being removed. There is some force in the string left over, but I never called that remnant force centripetal force, so why are you making out that I did? It is a force that comes from the flex in the pole.

I would call it centrifugal force, in a singular flavor of the concept, because in that case we could say it is an “active” force (action), and the centripetal one is a “reactive” force (reaction), when usually the opposite happens: centrifugal force is an inertial reaction to an “active” centripetal force …

That's fine, but when the centripetal force has gone entirely (when the ball's been stopped), that centrifugal force has also gone. All we have left is the force from the flex in the pole, and that is neither centrifugal nor centripetal.

I´m afraid that, as you consider centripetal force a “grey” area, adding those details could be a “black” area for you …

The questionable part of the application of the word is where you're labelling gravitational pull as centripetal force. I don't consider that valid because the gravitational force continues to act in full when the orbiting object is stopped.

The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite of what you say !!

Now I understand why you're getting this wrong. It's because you've got a lot of that right. There is one force applied by the ball to the string which spreads from ball to pole at the speed of sound (revealing the causation, which you ignore), and then another force is applied in the opposite direction to equalise it, starting at the pole and then ending at the ball, again spreading at the speed of sound, and it's this latter force that's called centripetal. The centripetal force then modifies the movement of the ball, but crucially it does not cause the movement of the ball - it merely modifies that movement.

The chain of causation is this: the ball moves --> it applies a force to the string --> centripetal force is generated in the string (the opposite way). With any chain of causation, if you to remove an intermediate item in the chain, what's left behind remains true, so we get: the ball moves --> centripetal force is generated in the string. We never get: centripetal force is generated in the string --> the ball moves. The ball was already moving. What we do have though is: centripetal force is generated in the string --> the movement of the ball is modified. You're conflating the movement of the ball and the modification of the movement of the ball, and that's where you're tripping up. Like I keep telling you, when you stop the ball, the centripetal force disappears as a result, and when you start the ball moving again, the centripetal force reappears as a result. The direction of causality is ball to pole. The direction of response is pole to ball, and this response then causally drives the modification of the movement of the ball.

And why does this matter? Again, let me focus your attention on the actual argument in question. With a ball on a string, centripetal force is generated by the movement of the ball. With an orbiting object, the force keeping it in orbit continues to apply in full when the ball has no movement - the movement of the orbiting object did not generate the gravitational force. No amount of diversion tactics will overturn these key facts.

[Le Repteux]

My two cents comment again! :0)

If we tie the ball to its far end through a hole in it, it will flatten instead of stretching, and if we tie it at many places with many strings, it will neither stretch nor flatten. For the ball to get deformed by the centripetal force the same way gravitation deforms the seas, the force on its close end has to be stronger than the force on its far end, but if we tie two balls to the same string and rotate them at the same time, on the contrary, the force on the closer one will be weaker than the force on the farther one. The equation is F=w²r, and w² is the angular velocity, so if r increases, the force automatically increases since w² is the same for both balls, which means that if gravitation would work this way, the seas would flatten instead of stretching.

[rmolnav]

Not necessary to refute that lot of errors. Anybody with a minimum of Physics education can see them.
But just a couple of things.

The questionable part of the application of the word is where you're labelling gravitational pull as centripetal force. I don't consider that valid because the gravitational force continues to act in full when the orbiting object is stopped.

What absurd a phrase last one! ... When did I label "gravitational pull as centripetal force". A gravitational pull (caused by a celestial object) can become a centripetal force if another object has a suitable speed vector to get an elliptical path, thanks precisely to that pull. E.g.: the pull exerted by earth on the moon ...
And, if for any reason the inertial tendency of the moon disappeared (e.g.: due to a sudden change of its velocity), the path would change, and the term "centripetal" could have no sense any more (if no proper rotation, no proper "center" where the pull were pointing at ...).
But as long as the rotation exists, the gravitational pull is a centripetal force !! 

The centripetal force then modifies the movement of the ball, but crucially it does not cause the movement of the ball - it merely modifies that movement.

Don´t twist my words. I´ve always said that the centripetal force causes the rotational movement, not just the "movement". And also that an initial speed vector, whatever the way it was originated, is logically necessary too !!

The chain of causation is this: the ball moves --> it applies a force to the string --> centripetal force is generated in the string (the opposite way).

Please kindly put it more clear:
1) "... centripetal force is generated ..." What do you mean with "generated" ??
2) "(the opposite way)" Opposite to what, to the by you previously mentioned force, or to the direction I say is the correct one ?

[David Cooper]

Not necessary to refute that lot of errors. Anybody with a minimum of Physics education can see them.

It doesn't do you any good repeatedly referring to correct things as errors - you just make yourself look more and more incompetent.

But just a couple of things.

The questionable part of the application of the word is where you're labelling gravitational pull as centripetal force. I don't consider that valid because the gravitational force continues to act in full when the orbiting object is stopped.

What absurd a phrase last one! ... When did I label "gravitational pull as centripetal force".

Are you reallyy incapable of working out what I'm referring to from the context of this conversation? You're calling it centripetal force in the case of a moon orbiting a planet.

A gravitational pull (caused by a celestial object) can become a centripetal force if another object has a suitable speed vector to get an elliptical path, thanks precisely to that pull. E.g.: the pull exerted by earth on the moon ...

And the reason I class that as a different category is that the force is not generated by the movement, which is why I question whether it should be called centripetal force at all. I've made that clear a good half dozen times now, but you don't take anything in. And this is just a side issue which you keep trying to divert things onto to hide the reality that the fundamental cause of the tides is gravitational force and not centripetal force. That is the big question under discussion here, and I have shown you the answer. The rest is just you engaging in diversion tactics because you don't like the answer.

And, if for any reason the inertial tendency of the moon disappeared (e.g.: due to a sudden change of its velocity), the path would change, and the term "centripetal" could have no sense any more (if no proper rotation, no proper "center" where the pull were pointing at ...).
But as long as the rotation exists, the gravitational pull is a centripetal force !! 

We're looking for the fundamental answer of the cause of tides, and that's gravitational pull and the difference in its strength over distance - not centripetal force. Your explanation is highly misleading.

The centripetal force then modifies the movement of the ball, but crucially it does not cause the movement of the ball - it merely modifies that movement.

Don´t twist my words. I´ve always said that the centripetal force causes the rotational movement, not just the "movement". And also that an initial speed vector, whatever the way it was originated, is logically necessary too !!

Why have you spent so much time then attacking what I've said about the movement of the ball causing the force to be generated if you've understood all along that it does exactly what I said it does? What's your game now? You realise you've been wrong, so you try to rewrite history as to what's happened in this conversation? Wll, the actual history of events is all still there for people to check. Tal vez, la problema es que no entiende Ingles bastante bien.

Please kindly put it more clear:
1) "... centripetal force is generated ..." What do you mean with "generated" ??

Y aqui habemos un ejemplo de eso - no entiende la palabra "generate". I mean exactly what the word says: if something is generated by something, it means it comes into existence because of that something. If a force is applied to something and causes it to move, the force generates the movement. If a movement causes a force to appear, it generates that force.

2) "(the opposite way)" Opposite to what, to the by you previously mentioned force, or to the direction I say is the correct one ?

The opposite way to the force being applied by the ball - the ball pulls one way on the string and the pole pulls the other. As the pole's pull on the string provides resistance, the ball pulls its force on the string higher and higher and the pole reacts by matching it. The force from the ball end (the cause) comes first, and the centripetal force from the pole end (the result) is in every part a response driven by the cause.

[rmolnav]

Oxford Dictionary
"Centripetal force":
Noun.
A force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.
Example sentences
‘Newton analysed the motion of bodies in resisting and non-resisting media under the action of centripetal forces.’
‘Now, if we set a cylindrical space station in rotational motion at a certain angular velocity, anything that moves with it will need a centripetal force to keep it rotating with the station.’
‘Armed with his conception of material space, which was the location of gravity, combined with the constant action of the centripetal force of universal gravitation, Toland believed he had accounted for all phenomena in the universe.’

[David Cooper]

Oxford Dictionary
"Centripetal force":
Noun.
A force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.
Example sentences
‘Newton analysed the motion of bodies in resisting and non-resisting media under the action of centripetal forces.’

Lovely - you have a justification for using the word centripetal with gravity. That doesn't negate the fact that there are two different cases which need to be differentiated between: (1) a case where centripetal force is generated by the movement of the thing going round [and where it disappears if the object is stopped], and (2) a case where centripetal force is not generated by that movement but is 100% independent of it [and where it continues to act if the object is stopped]. This is why I don't like the use of the word centripetal in the latter case, but if other people are happy to use it with such semantic ambiguity, that's fine, just so long as they understand the two different cases and don't allow it to contaminate their understanding of things like tides.

In the case of tides, the movement is irrelevant because the gravitational force and the bulges remain if the movement is removed, and this reveals that the cause of the tides is not centripetal force. By claiming it is, you mislead people into thinking that the movement is fundamentally a part of the cause, but it is incidental to it.

A case with a ball on a string being distorted out of shape as it swings round in circles is very different - the distortions there are actually caused by centripetal force. Stop the ball moving, and the force disappears to prove it.

[rmolnav]

... a case where centripetal force is generated by the movement of the thing going round [and where it disappears if the object is stopped]

Again:
1) In cases where a string, rope, wire or chain transfer the centripetal force to the rotating object, ONLY if there is an active supply of energy at the inner end of the linking device, could the object keep rotating for some time. "Your" cases are only transient movements.
2) In any case, what you "see" in those cases has a certain reality, but you interpret it wrongly.
I wish not to have to mention "centrifugal force": you handle the term "centripetal" so erroneously, that it will be much tougher to discuss with you "centrifugal" one ...
What you see, rather than "the movement causes the centripetal force", could be expressed "the movement originates a CENTRIFUGAL force", because both the inertia of the object (tending to follow the tangent), and the centripetal force, are required for the rotation of the object.
As I said some days ago:

Hitting a ball produces a transference of momentum, always through forces. At the very initial instant some deformations (of the ball and the bat) occur, what produces opposite pushes on each other, which then change both speed vectors … The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite to what you say !!

This is why I don't like the use of the word centripetal in the latter case, but if other people are happy to use it with such semantic ambiguity

Come on! It is not just "other people" ... I could post here a huge amount of dictionaries and Physics texts using the term same way. The problem is yours, not:

...that's fine, just so long as they understand the two different cases and don't allow it to contaminate their understanding of things like tides.

The very common confusion on tides, rather than from the term "centripetal force" (clear for almost everybody) comes from the concept of "centrifugal force".

[David Cooper]

1) In cases where a string, rope, wire or chain transfer the centripetal force to the rotating object, ONLY if there is an active supply of energy at the inner end of the linking device, could the object keep rotating for some time. "Your" cases are only transient movements.

If a ball is attached by a string to a massive lump of lead in deep space and is set moving round it in circles (with the massive object rotating to avoid tangling), this would keep going round and round forever. The generation of centripetal force would be continuous, and it's generated by the movement. Remove all the rotation and the centripetal force disappears. There is no active supply of energy at the inner end.

2) In any case, what you "see" in those cases has a certain reality, but you interpret it wrongly.
I wish not to have to mention "centrifugal force": you handle the term "centripetal" so erroneously, that it will be much tougher to discuss with you "centrifugal" one ...

The misinterpretations are all yours, but you seem incapable of recognising that. Time and time again you produce errors which you never acknowledge when your errors are made clear to you - you just go on claiming to be right and keep accusing me of making errors (which I haven't made). It's a pantomime.

What you see, rather than "the movement causes the centripetal force", could be expressed "the movement originates a CENTRIFUGAL force", because both the inertia of the object (tending to follow the tangent), and the centripetal force, are required for the rotation of the object.

There are many valid wordings and descriptions, but the movement causes the centripetal force to be generated regardless of how you word it. Removing the movement removes the centripetal force, and reintroducing it restores it. Straightforward cause and effect. Removing the movement in an orbiting system though and the gravitational force does not vanish.

As I said some days ago:

Hitting a ball produces a transference of momentum, always through forces. At the very initial instant some deformations (of the ball and the bat) occur, what produces opposite pushes on each other, which then change both speed vectors … The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite to what you say !!

You won't gain anything by repeating that. The direction of causation is exactly as I stated regardless of how much irrelevant detail you want to go into, and all my descriptions are correct. If you're saying the opposite to me, then you must be wrong. We both appear to agree that the centripetal force causes the rotational movement (the change in movement of the ball), but the movement of the ball itself is what causes the the centripetal force to appear and the centripetal force merely modifies it by changing the direction of travel of the ball (while the ball moves at a constant speed).

This is why I don't like the use of the word centripetal in the latter case, but if other people are happy to use it with such semantic ambiguity

Come on! It is not just "other people" ... I could post here a huge amount of dictionaries and Physics texts using the term same way. The problem is yours, not:

This is a side issue about the use of the word centripetal in relation to gravity. I simply made the point that I consider it to be an unwise usage of the word because the force exists regardless of the rotation. That's a perfectly reasonable point for me to make, and all the more so when the result of this usage leads to you making such errors in your understanding of tides. It is an area of labelling which needs to be cleaned up in order to remove ambiguity. I can't help it though if other people keep tying themselves to a mess.

...that's fine, just so long as they understand the two different cases and don't allow it to contaminate their understanding of things like tides.

The very common confusion on tides, rather than from the term "centripetal force" (clear for almost everybody) comes from the concept of "centrifugal force".

The confusion here has nothing to do with misunderstandings related to the use of the term centrifugal force. We don't need the word or idea in the discussion at all. The confusion here is with centripetal force where you are attributing tides to a force related to rotation even though the tides are actually caused directly by differential gravity and do not depend on orbiting. You are trying to drag the rotation in as a fundamental part of the cause, and that is plain wrong. The rotation and centripetal force have no place in the fundamental explanation.

[rmolnav]

#210 David Cooper
I could easily refute many of those paragraphs, erroneous either to Physics or to Logics (or to both) … But I know it´d be useless, and I won´t do it.
Instead I´m going to refute what seems to be the very “foundation” of your stand. And using same arguments that constitute your kind of pseudo-bible, that keeps you despising many scholars´s statements, and twisting basic Physics laws.
You´ve said a lot of times something like: if we “remove" the revolving movement of earth, the bulges remain … So, that movement cannot be causing the tides.
I already did refute a similar idea of yours (#145), in relation with your idea of a mega-spaceship causing bulges. But you didn´t get it, and said I had taken your case in the wrong way !!
Let us forget the spaceship, and have just moon and earth.
If, somehow, we "remove" the revolving, both earth and moon will accelerate towards each other … Though only a transient movement, bulges would remain (and increase) until the collision. OK. Therefore, revolving was not causing them (YOUR deduction).
IN A QUITE SIMILAR WAY, we could reason as follows:
If, somehow (a “megaman” grasping the earth at its c.g…?), we “removed” that rectilinear, accelerated movement of earth towards the moon, outer bulge would not only disappear, but even change its sign, because outer earth hemisphere would get additional internal compressive stresses (before they were tensile s.), due to moon´s pull (though smaller than tensile stresses within inner hemisphere, closer to the moon …)
Therefore, if with the differential moon´s gravity maintained, outer positive bulge doesn´t exist, the moon differential gravity cannot be the cause of outer bulge !!
Same way you´ve “reasoned” lot of times … Either both are right, or both are wrong …
Any guess ??

[David Cooper]

I could easily refute many of those paragraphs, erroneous either to Physics or to Logics (or to both) … But I know it´d be useless, and I won´t do it.

You could try to, but you'd fail.

You´ve said a lot of times something like: if we “remove" the revolving movement of earth, the bulges remain … So, that movement cannot be causing the tides.
I already did refute a similar idea of yours (#145), in relation with your idea of a mega-spaceship causing bulges. But you didn´t get it, and said I had taken your case in the wrong way !!

You didn't refute it, and you clearly didn't get it either - you just did your usual thing of confusing yourself with extraneous factors which I didn't go into (you should have been able to rule them all out by imagining the Earth being pulled along by an evenly-applied tractor beam from the spaceship). Maybe you'd see it more clearly if you switch the moon and Earth over so that the moon's being pulled by the spaceship instead and the Earth is accelerating after it, but never able to catch up. Now the only factor is the moon's pull on the Earth and the differential gravity causing the two tidal bulges which persist for the longterm with no rotation being involved.

Let us forget the spaceship, and have just moon and earth.
If, somehow, we "remove" the revolving, both earth and moon will accelerate towards each other … Though only a transient movement, bulges would remain (and increase) until the collision. OK. Therefore, revolving was not causing them (YOUR deduction).

Indeed - they were not caused by rotation or centripetal force.

IN A QUITE SIMILAR WAY, we could reason as follows:
If, somehow (a “megaman” grasping the earth at its c.g…?), we “removed” that rectilinear, accelerated movement of earth towards the moon, outer bulge would not only disappear, but even change its sign, because outer earth hemisphere would get additional internal compressive stresses (before they were tensile s.), due to moon´s pull (though smaller than tensile stresses within inner hemisphere, closer to the moon …)
Therefore, if with the differential moon´s gravity maintained, outer positive bulge doesn´t exist, the moon differential gravity cannot be the cause of outer bulge !!
Same way you´ve “reasoned” lot of times … Either both are right, or both are wrong …
Any guess ??

The removal of rotation does not remove the tidal bulges - they remain, but clearly the Earth has to be free to accelerate towards the moon for this to be the case. If you hold the Earth in position, then you have a different result where a single bulge will appear on the side nearest the moon. With the ball on the string, when you stop the rotation, the ball simply sits there with all the distortion removed - there is no continuation of a force trying to pull it towards the centre of the now-lost rotation because that centripetal force has gone, unlike in the gravity case where it continues to apply in full. If you want to apply a force though to maintain the distortion on the ball you can do that, but it wouldn't be centripetal force - this new force would produce the same distortion if the ball's still free to move as it had on it when it was going round in circles, and if you held the ball so that it couldn't move, it would produce a different distortion more like the one in the case where you hold the Earth and don't let it accelerate towards the moon. But, start the ball moving round in circles again and what happens? The centripetal force is restored and the extra force you added to the system will now shorten the string and pull the ball in, because adding that force was cheating. The key difference remains: the gravitational pull is not lost when the rotation stops in one system, but the centripetal force in the string disappears when the rotation stops in the other system. One of these forces is generated by the rotation, but the other isn't, and the one that isn't (i.e. gravity) continues to produce the tidal bulges.

I have no expectation that all of that won't go straight over your head like everything else and you'll fool yourself into imagining that you can refute it, but perhaps it will register with other people who read this.

[rmolnav]

The removal of rotation does not remove the tidal bulges - they remain, but clearly the Earth has to be free to accelerate towards the moon for this to be the case. If you hold the Earth in position, then you have a different result where a single bulge will appear on the side nearest the moon

There we are! (surely it´s a lapse of yours, and you meant "the removal of the rectilinear movement" ...)
It´s unbelievable that you consider absolutely necessary to let the earth free to get the rectilinear accelerated movement towards the moon (to have the second bulge), but time and again you say that (as it is in the real case) the curved accelerated movement of the earth (its revolving around the moon-earth barycenter), has nothing to do with the formation of the outer bulge, and that it is not necessary at all !!
They are two different ways inertia manifests itself, but due to same basic Physics laws ...
In the first case, outer hemisphere massive stuff kind of "falls behind", because it is not sufficiently pulled by the moon to get the rectilinear acceleration of the whole earth. The whole earth stretches, and behind bulge also appears.
In the real case, outer bulge equally requires the revolving movement, because outer hemisphere massive stuff is not sufficiently pulled by the moon to get the required centripetal acceleration for the revolving movement. Internal stresses (in both senses, inwards and outwards) appear, earth stretches too, and outer bulge builds too ...
But with your basic Physics misconceptions, I´m afraid you´ll carry on not accepting that !!

[David Cooper]

The removal of rotation does not remove the tidal bulges - they remain, but clearly the Earth has to be free to accelerate towards the moon for this to be the case. If you hold the Earth in position, then you have a different result where a single bulge will appear on the side nearest the moon

There we are! (surely it´s a lapse of yours, and you meant "the removal of the rectilinear movement" ...)

I meant exactly what I said. Rewording it makes no difference.

It´s unbelievable that you consider absolutely necessary to let the earth free to get the rectilinear accelerated movement towards the moon (to have the second bulge), but time and again you say that (as it is in the real case) the curved accelerated movement of the earth (its revolving around the moon-earth barycenter), has nothing to do with the formation of the outer bulge, and that it is not necessary at all !!

There's nothing unbelievable about it - if the Earth and moon fall together along a straight line, the tidal bulges are both there, and will grow in size for several days until the collision. The other movement that we have with the Earth and moon at 90 degrees to the line between them is irrelevant to the cause of those bulges.

They are two different ways inertia manifests itself, but due to same basic Physics laws ...
In the first case, outer hemisphere massive stuff kind of "falls behind", because it is not sufficiently pulled by the moon to get the rectilinear acceleration of the whole earth. The whole earth stretches, and behind bulge also appears.

That indeed is the cause of the tidal bulges - differential gravity with the Earth and moon being accelerated towards each other and without any need of the orbit.

In the real case, outer bulge equally requires the revolving movement, because outer hemisphere massive stuff is not sufficiently pulled by the moon to get the required centripetal acceleration for the revolving movement. Internal stresses (in both senses, inwards and outwards) appear, earth stretches too, and outer bulge builds too ...
But with your basic Physics misconceptions, I´m afraid you´ll carry on not accepting that !!

The revolving aspect can be ignored. The pull of the Earth and moon upon each other in a straight line is all you need for the tidal bulges. The sideways movement is simply an addition to it (which conveniently prevents a collision), and having that  incidental sideways component of movement involved is not any justification for claiming that the tidal bulges are generated by centripetal force. At any point in time you have two vectors for the movement of the Earth or moon (with one running along the imaginary line between the two bodies and the other at 90 degrees to it), and two vectors for the acceleration being applied by each body on the other, again with one acting along the invisible line between the two bodies and the other perpendicular to it. The first of these acceleration vectors is never zero but the latter is always zero. It doesn't matter a damn what what the perpendicular action is - the bodies accelerate towards each other (without necessarily getting any closer together) and the material on each body that's closest to the other body is pulled more strongly while the material furthest away is pulled less strongly, and that is all that's involved in the production of the bulges. The perpendicular movement adds nothing to them. All you're doing is claiming that centripetal force causes the tidal bulges on the basis that there is normally orbital rotation involved, but that's s nonsense as the same bulges exist when you remove that orbital movement and reduce things to a straight line case. That's why physicists don't agree with you.

The only case you might have would be if you were to claim that the straight-line case is a special case of rotation and that the word "centripetal" should include it too as part of its remit, in which case when you slam the brakes on in a car while it's moving in a straight line, you are thrown forward and centripetal force acts on you via the seatbelt. If you want to make that argument, I'll be happy to back you up and join the call to include that in the definition of centripetal so that it is no longer associated solely with cases involving curved paths. However, even then, if you insist on classing gravity as centripetal force (and also logically apply the new definition of centripetal to straight-line action), you then have people jumping up in the air and being pulled straight back down by centripetal force. Do all the physics books have to be rewritten to say that centripetal force causes things to fall rather than gravity? No - the fundamental explanation of why things fall is gravity, just as the fundamental cause of the tides is differential gravity. And you also still have the key difference between two cases with things moving in circular paths where in one case the rotational movement generates the centripetal force in the string, and in the other case the rotational movement doesn't (and where the force in the invisible string, gravity, continues to act in full regardless of whether the object is orbiting or not). Even if you class both of these as centripetal and don't consider one case to be more of an analogy, they are radically different beasts in nature which should not be given the same label.

Your attempt to attribute tidal bulges to centripetal force remains at odds with physics though with the way the word centripetal is currently defined (with curved paths being a requirement), and that should be sufficient cause in itself for you to desist. The straight-line case produces the same bulges and demonstrates that you are plain wrong on the whole issue.

[rmolnav]

#214 David Couper
What a lot of absurdities … and false statements !!
In the first place, I neither ever:
… have claimed "that centripetal force causes the tidal bulges” (or other equivalent expressions of you)
… let alone have "classified gravity as centripetal force” (!!)
Again, not even in my wildest dreams could I have thought I was going to have to explain something such as what follows … But I´ll do it, rather than because of you (you seem to need a change of some of your mind “chips”), not to let unanswered all that rubbish, and for the sake of the interest of others.
In relation to a noun such as “force”, one thing is its nature, or its essence, and quite another its let us say function, or its not essential characteristics, what usually is expressed through adjectives.
A force can be big, small, permanent, variable, pulling or pushing contact f., “at a distance f." (not sure the correct English name) … as well as centripetal or centrifugal, a possible additional quality in specific cases, NOTHING TO DO with “classifying gravity as centrifugal force” !!
Different types of forces (or components of forces) can act as centripetal forces, as long as their directions are perpendicular to the affected object trajectory, and in the sense of a “center” (of the circle if circular movement, or the center of curvature if other curved paths).
Gravitational force can act as centripetal force, as long as what above occurs.
E.g.: the parabolic trajectory of a cannon ball is due to the gravitational force action (and the initial speed vector): its tangential component changes the size of the speed, and its component perpendicular to speed vector, acting as a centripetal force, curves the trajectory, not letting the ball to follow its inertial tendency to continue straight …
I previously posted:
"If e.g you google "phisics.ohio-state.edu" and go to "Dynamics of Uniform Circular Motion" (Chapter 5, 5.3 Centripetal Force), you can read (apart from many other things and formulas):
"...Thus, in uniform circular motion there must be a net force to produce the centripetal acceleration.
The centripetal force is the name given to the net force required to keep an object moving on a circular path".
But you just answered:
"It doesn't matter how much justification you can find for calling it centripetal force. This is a grey area in which some usages of the word aren't fully rational (!!)"
 And when I posted what Oxford Dictionary says:
"A force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.
Example sentences
‘Newton analysed the motion of bodies in resisting and non-resisting media under the action of centripetal forces.’
‘Now, if we set a cylindrical space station in rotational motion at a certain angular velocity, anything that moves with it will need a centripetal force to keep it rotating with the station.’
‘Armed with his conception of material space, which was the location of gravity, combined with the constant action of the centripetal force of universal gravitation, Toland believed he had accounted for all phenomena in the universe’,
you just commented
 “... a case where centripetal force is not generated by that movement but is 100% independent of it [and where it continues to act if the object is stopped]. This is why I don't like the use of the word centripetal in the latter case, but if other people are happy to use it with such semantic ambiguity, that's fine, just so long as they understand the two different cases and don't allow it to contaminate their understanding of things like tides".
No wonder you said centripetal force is a grey area.
I repeat: you draw wrong conclusions (100% right for you !!) from a rather singular and arguable case (the movement of a ball-string-fixed pole around the later, which according to you causes a "centripetal force”, whatever you mean with that term), and are unable to see in nature things happen differently.
By the way, I was going to leave what related to my supposed claim "that centripetal force causes the tidal bulges” for another post, because unless we previously clarify what you actually mean with the term, any discussion would be an additional waste of time …
But just one thing now: what I have said several times is that CENTRIFUGAL forces are ONE of the causes of the bulge more distant from the moon, rather the opposite to what you seem to think I say !!.
As early as in one of my very first posts here (#24), more than three years ago, I already said:
"Imaging an athlete of hammer trow speciality. He or she can´t keep verticality when throwing the hammer. It is necessary to lean a little backwards. Otherwise the hammer could not be rotated. Both the athlete and the hammer will rotate around an axis situated near the forward part of the athlete´s body.
If the hair of the athlete is long and not  fixed by some device, instead of keeping its normal downward direction due to its weight, it will move back and upwards …
That cannot be due to anything similar to what stated by Schutz relative to tides: CENTRIFUGAL force is the cause"
But other times I tried and avoided the use of such a controversial term, and said, as on post #213:
“… They are two different ways inertia manifests itself, but due to same basic Physics laws ...
In the first case (linear accelerated movement), outer hemisphere massive stuff kind of "falls behind", because it is not sufficiently pulled by the moon to get the rectilinear acceleration of the whole earth. The whole earth stretches, and behind bulge also appears.
In the real case, outer bulge equally requires the revolving movement, because outer hemisphere massive stuff is not sufficiently pulled by the moon to get the required centripetal acceleration for the revolving movement. Internal stresses (in both senses, inwards and outwards) appear, earth also stretches, and outer bulge builds too …”
But you have in your head many absurdities about the pretty simple concept of “centripetal force”, and have proved unable to grasp it … I can´t imagine what there can be in your mind in relation to the rather tricky concept of “centrifugal force” ...

 
 

 
 

[David Cooper]

#214 David Couper
What a lot of absurdities … and false statements !!
In the first place, I neither ever:
… have claimed "that centripetal force causes the tidal bulges” (or other equivalent expressions of you)
… let alone have "classified gravity as centripetal force” (!!)

What you have consistently done is deny the correct explanation whenever it's been put to you, and you've harped on and on about centripetal force instead, so forgive me for failing to understand that you actually agree with the correct explanation and for not recognising that it's a mere illusion that you've spent weeks arguing against it.

"If e.g you google "phisics.ohio-state.edu" and go to "Dynamics of Uniform Circular Motion" (Chapter 5, 5.3 Centripetal Force), you can read (apart from many other things and formulas):
"...Thus, in uniform circular motion there must be a net force to produce the centripetal acceleration.
The centripetal force is the name given to the net force required to keep an object moving on a circular path".
But you just answered:
"It doesn't matter how much justification you can find for calling it centripetal force. This is a grey area in which some usages of the word aren't fully rational (!!)"

That's all well and lovely, but what you shouldn't be doing is claiming that the force acting on the object is centripetal rather than gravity when it's gravity that's doing the job and any justification for labelling it as "centripetal" is an irrelevance. What you're also repeatedly doing is ignoring the issue in question and obsessing over other arguments which you're then misrepresenting by taking quotes out of context. I've made it very clear multiple times that physics should be making a clear distinction between centripetal force that's generated by a movement and "centripetal" force that's there regardless of the movement because it is not generated by it, and that this distinction is crucial to the central point of our argument because when the movement stops, the force continues to act in full, demonstrating that the cause of tidal "bulges" should not be attributed to centripetal force. That is all there is to it. You lost that argument, but you're incapable of admitting it, and all you're doing now is playing games to hide the fact that you lost it.

And when I posted what Oxford Dictionary says:

I told you long ago that if you want to call it "centripetal" in cases where the force is not generated by the movement, that's fine - there are plenty of definitions that agree with you. All I said was that I think it's a mislabelling issue in physics which should be tidied up in that it ignores an ambiguity, and that this ambiguity is deeply damaging in that it's causing people like you to make massive mistakes in your understanding. But this is all a separate issue from the one in question in this thread. I don't like sloppy labelling systems, but no amount of attacking me on the basis of established usage over my disagreement with the way labels are used will alter the fact that the cause of tidal "bulges" is straight-line differential gravity. You still refuse to acknowledge the point that when the movement stops, the force continues to act and the cause of tides is revealed to have no dependency on centripetal force.

I repeat: you draw wrong conclusions (100% right for you !!) from a rather singular and arguable case (the movement of a ball-string-fixed pole around the later, which according to you causes a "centripetal force”, whatever you mean with that term), and are unable to see in nature things happen differently.

So you're still unable to understand that bit. It's all perfectly simple: the movement of the ball generates the centripetal force in the string. Stop the ball and the centripetal force disappears. Start it moving again and the centripetal force returns. That is how it happens in nature. Do the same thing with orbiting objects and you get a very different result. I don't know what it is that stops you from understanding this simple thing, but that inability is your key problem.

But just one thing now: what I have said several times is that CENTRIFUGAL forces are ONE of the causes of the bulge more distant from the moon, rather the opposite to what you seem to think I say !!.

I may well have got the wrong impression about how much you attribute the "bulges" to the actual cause and how much you attribute it to centripetal/centrifugal force, but I did ask you early on what proportion of it you imagined to be caused by the latter and you simply ignored the question. None of that really matters though, because centripetal/centrifugal force isn't even one of the causes. The cause is straight-line differential gravity alone.

As early as in one of my very first posts here (#24), more than three years ago, I already said:
"Imaging an athlete of hammer trow speciality. He or she can´t keep verticality when throwing the hammer. It is necessary to lean a little backwards. Otherwise the hammer could not be rotated. Both the athlete and the hammer will rotate around an axis situated near the forward part of the athlete´s body.
If the hair of the athlete is long and not  fixed by some device, instead of keeping its normal downward direction due to its weight, it will move back and upwards …
That cannot be due to anything similar to what stated by Schutz relative to tides: CENTRIFUGAL force is the cause"

It that example, centripetal/centrifugal force can validly be be described as the cause of the equivalent of tidal forces because it stops acting if you remove the movement that generates it. With gravity and orbits though, that isn't the case - stop the movement and the "bulges" remain.

But other times I tried and avoided the use of such a controversial term, and said, as on post #213:
“… They are two different ways inertia manifests itself, but due to same basic Physics laws ...
In the first case (linear accelerated movement), outer hemisphere massive stuff kind of "falls behind", because it is not sufficiently pulled by the moon to get the rectilinear acceleration of the whole earth. The whole earth stretches, and behind bulge also appears.

Fine - that's straight-line differential gravity in action on an object that's free to move, so why all the disagreement if you actually do understand the correct mechanism?

In the real case, outer bulge equally requires the revolving movement, because outer hemisphere massive stuff is not sufficiently pulled by the moon to get the required centripetal acceleration for the revolving movement. Internal stresses (in both senses, inwards and outwards) appear, earth also stretches, and outer bulge builds too …”

In the real case, straight-line differential gravity is all it takes - there is no need to try to manufacture extra factors for it. Take two cases for example where there is no perpendicular movement to the gravitational force: place the planet and moon the same distance apart in each case, but in one case have them moving towards each other and in the other case moving apart (along a straight line). Do we get different bulges at that moment where they are that certain distance apart? No. The same acceleration force is being applied, and it's the same amount of difference in acceleration force being applied across the moon/planet from one side to the other, leading to the same size of "bulges" (pressure differences). Then consider a third case where there is perpendicular movement and at that moment no movement away from or towards the other body. Is there any difference to the "bulges"? No. The sideways movement is completely irrelevant as it has no role in forming the bulges. Consider all other angles at which the planet and moon might be moving relative to each other, and ask the same question: are the "bulges" different at a given separation in any of these cases? No. They are not.

But you have in your head many absurdities about the pretty simple concept of “centripetal force”, and have proved unable to grasp it … I can´t imagine what there can be in your mind in relation to the rather tricky concept of “centrifugal force” ...

The absurdities are all on your side. I clearly understand the physics better than you do - you are using labels in ways that confuse you by making you think two radically different systems are the same, and the result is that you drag something into an explanation of tides that doesn't belong there. All I've done is try to help you stop confusing yourself with labels so that you'll look at the actual causation instead, but you just can't do it. The only thing that matters here is the cause of the bulges, and centripetal/centrifugal force is an irrelevance to them because they are determined by straight-line differential gravity. The size of the "bulges" is determined by the distance between the moon and Earth regardless of how they're moving relative to each other at the time. There is no magical addition to their size by the relative movement of the two bodies - it's all determined by the straight-line acceleration.

[Le Repteux]

If I may,

Molnav, the force applied to a large body made out of particles cannot be treated the same as the force applied to each of its particles taken separately, and you seem to think so. In the case of a body, we need an anchor to hold it, but we can't hold a particle with an anchor. The moon and the earth are not anchored to one another, instead, it is each particle from each of the bodies that is linked to all the particles of the other body by means of the gravitational force, and that force depends on distance, which is not the case with a string. If we would anchor all the particles of the moon to all the particles of the earth by means of strings, there would be no bulge, but since the gravitational force weakens with distance, the closer particles are pulled more strongly than the farther ones and it creates bulges.

[rmolnav]

#216 and #217
Most people will be able to see which side the absurdities are on. So, to refute once more many of them is unnecesary … But:

So you're still unable to understand that bit. It's all perfectly simple: the movement of the ball generates the centripetal force in the string. Stop the ball and the centripetal force disappears. Start it moving again and the centripetal force returns. That is how it happens in nature (??). Do the same thing with orbiting objects and you get a very different result ...

Another day with more time I´ll come back to what quoted, which seems to be one of the roots of that unsolvable puzzle of wrong ideas deep in your mind. In line with what I said about how things happen when we hit a ball attached through a string to a pole (#202)
"Hitting a ball produces a transference of momentum, always through forces. At the very initial instant some deformations (of the ball and the bat) occur, what produces opposite pushes on each other, which then change both speed vectors … The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite of what you say !!"
By the way, as usual you replied with more absurdities:
"Now I understand why you're getting this wrong. It's because you've got a lot of that right. There is one force applied by the ball to the string which spreads from ball to pole at the speed of sound (revealing the causation, which you ignore), and then another force is applied in the opposite direction to equalise it, starting at the pole and then ending at the ball, again spreading at the speed of sound, and it's this latter force that's called centripetal. The centripetal force then modifies the movement of the ball, but crucially it does not cause the movement of the ball - it merely modifies that movement".
I have another case in mind, perhaps easier to understand, but I have to draft it very carefully, to diminish the possibilities of you to misunderstand and/or twist my words !!
But now just another thing.

... the force applied to a large body made out of particles cannot be treated the same as the force applied to each of its particles taken separately, and you seem to think so. In the case of a body, we need an anchor to hold it, but we can't hold a particle with an anchor. The moon and the earth are not anchored to one another, instead, it is each particle from each of the bodies that is linked to all the particles of the other body by means of the gravitational force, and that force depends on distance, which is not the case with a string. If we would anchor all the particles of the moon to all the particles of the earth by means of strings, there would be no bulge, but since the gravitational force weakens with distance, the closer particles are pulled more strongly than the farther ones ...

OK. But it is equivalent to consider each particle of the earth linked by means of a somehow elastic string to moon´s c.g., certainly with tensions (gravity pull) the shorter the string, the stronger.
But you seem to forget that each earth particle is also linked much more strongly to the rest of the earth, to its c.g. if you wish: its own weight.
Being that hundreds of thousand times bigger than moon´s pull (at earth´s surface), we could say all earth particles are kind of anchored to earth´s c.g., rather than simply “linked”. Though also through not completely rigid strings (especially when water particles).
Due to that, all those particles are not actually free to accelerate as answer to moon´s pull whatsoever … They have a certain freedom though. The way the whole earth moves is paramount to the type and degree of freedom our planet allows each of individual particles …
The whole planet “forces” each of its particles to move “together”, and the distribution of inherent internal stresses depends on the movement of the whole, not only on the differential gravity from moon. And those internal stresses (their change due to moon-earth rotation/revolving) are the ultimate cause of tides.
If we were analyzing tidal effects of earth pull on the moon, internal stresses there would be relatively higher, because not only gravity decreases to the square of the distance: required centripetal force (mω²r) increases proportionally to the distance. Therefore the imbalance between local pull from earth (which ought to cause each particle rotation), and the required centripetal force, increases more with the distance …Or, if you wish, the further the particle, the higher the centrifugal force.
That´s why to say earth revolving (and forces inherent in that type of movement) doesn´t intervene on tides is utterly erroneous ...   

 
 

[David Cooper]

#216 and #217
Most people will be able to see which side the absurdities are on. So, to refute once more many of them is unnecesary …

Indeed they will - it's a straight-line force being applied by gravity where the perpendicular movement is irrelevant.

"Hitting a ball produces a transference of momentum, always through forces. At the very initial instant some deformations (of the ball and the bat) occur, what produces opposite pushes on each other, which then change both speed vectors … The ball gets a speed, and its inertia tries to make it go straight … If a string attached to a pole prevent that to happen, what the ball´s inertia does (its “movement”, in your words) is to tighten the string: it pulls outward the string outer end, and the string inner end will pull on the pole … The pole will react exerting an equal but opposite force on the string (3rd Newton´s Motion Law), a centripetal force … THAT centripetal force makes the rectilinear movement of the ball change into circular movement, that is, it causes the rotational movement … Quite the opposite of what you say !!"

Your interpretation skills are woeful - nothing in that is in conflict with what I said, until you say "Quite the opposite to what you say". You're just playing silly games to divert attention away from the fact that you've lost the argument, in this case by refusing to understand what I mean by "the movement of the ball". The ball is only moving because it's been hit by a bat - that input of force is what sets it moving, and that movement causes the centripetal force to be generated, and that force in turn modifies the movement of the ball. You are then labelling that modified movement as "the movement of the ball" and are attacking me for claiming that that generates the centripetal force, but that is clearly not what I claimed at any time. When I refer to the movement of the ball, I'm referring to the fact that the ball is moving and not to how it's moving. The ball's movement generates the centripetal force and the centripetal force then modifies the way the ball moves. That is what I have said throughout, and it remains fully correct. Stop the ball and the centripetal force disappears.

To help you understand this mind-numbingly simple point, think about it in terms of kinetic energy. The bat hitting the ball gives the ball kinetic energy. That kinetic energy stays with the ball as it goes round and round the pole, and it leads to forces being generated in the string, one of which is the centripetal force that changes the direction the ball is moving in, but it doesn't add or subtract kinetic energy from the ball - it merely changes the direction the ball's moving in. So, when I (rightly) say the movement of the ball generates the centripetal force, I'm referring to the movement of the ball that results from this energy being added to it, and that movement then generates centripetal force which doesn't change the energy that the ball is carrying other than the direction that energy's moving in. When I stop the ball, I remove that energy from it and the centripetal force disappears. At no time does the centripetal force change the amount of movement energy that the ball is carrying, and that's what I'm referring to when I say that it does not cause the movement - all it does is modify the movement by changing the direction the ball is moving in.

By the way, as usual you replied with more absurdities:

No; I replied with more correct statements which you consider to be absurdities because you are highly irrational and totally deluded about your thinking capabilities.

The whole planet “forces” each of its particles to move “together”, and the distribution of inherent internal stresses depends on the movement of the whole, not only on the differential gravity from moon. And those internal stresses (their change due to moon-earth rotation/revolving) are the ultimate cause of tides.

The rotation is a separate issue which merely makes the part near the equator stick out more than it does towards the poles - that rotation is practically constant and the bulge it produces has no role in the tides. If the moon didn't exist, the Earth would still be that shape because of its own rotation, and that is not part of tides so you should not be treating it as a component of tides. Your second sentence is plain ridiculous - the "moon-earth rotation/revolving" part of it is the objectionable bit as it does not cause the tides on the Earth - the ultimate cause of tides is the differential gravity with its straight-line acceleration.

If we were analyzing tidal effects of earth pull on the moon, internal stresses there would be relatively higher, because not only gravity decreases to the square of the distance: required centripetal force (mω²r) increases proportionally to the distance. Therefore the imbalance between local pull from earth (which ought to cause each particle rotation), and the required centripetal force, increases more with the distance …Or, if you wish, the further the particle, the higher the centrifugal force.

The straight-line acceleration already provides all the force difference involved without any need to bring centripetal force into it.

That´s why to say earth revolving (and forces inherent in that type of movement) doesn´t intervene on tides is utterly erroneous ...

The earth's revolving certainly does impact on the way tides present themselves. If the Earth was rotating once a month, permanent bulges would form on two opposite sides and they would then grow and shrink a little throughout each month as the moon gets closer and further away. The moon's orbit not being circular would also make the bulges move east and west a bit because the Earth's rotation wouldn't track the moon's position in the sky perfectly. The Earth's actual rotation prevents such bulges from forming (because the water can't move fast enough to keep up), so we just have tiny pressure changes acting over a huge area and adding enough energy to generate oscillations that provide the tides that we see. The cause of it all though is the straight-line differential gravity and not centripetal force. The rotation of the Earth means that the direction straight-line differential gravity is applied in changes all the time, but that isn't a centripetal force issue. And as I keep pointing out, you can remove all rotation from the system and the "bulges" (pressure differences) remain in place, which is what shows that centripetal force does not cause them. Not only does it not cause them, but it doesn't even add to them.

If I was to write a computer program to simulate this and show the forces applying on the surface of the Earth and moon, I would do it as follows. Let's name three points of each body: EC is the centre of the Earth, EN is the point on the surface of the Earth nearest the moon, EF is the point on the surface of the Earth furthest from the moon, while MC, MN and MF are the equivalent points on the moon. To calculate the tidal force on the Earth at point EN, I'd simply find the difference between gravitational force applied to EC and EN, while for  point EF I'd find the difference between the gravitational force applied to EC and EF. Having done that, I could subtract the results from 10 to get the force that would be felt by objects standing on the surface at those points (measured in units called Newts). This is based on 10 being the number of Newts that would be recorded at the equator if the moon wasn't present, but note that the centripetal force aspect is already accounted for in that figure. (At the poles, the value would be higher than 10 because there is no centripetal force acting on them to suppress it.) I would not add any extra centripetal force to those numbers in the way you seek to do because it has already been fully accounted for - we should certainly not deal with this rotation-driven equatorial bulge by factoring it in afterwards and trying to pass it off as part of the tides.

However, you appear to want to make a centripetal addition to the results, so I want to know how you imagine that it should apply so that it can be added to the program. We'll then be able to see whether you're double-counting it (or just counting it late and mistaking it for part of the tides), and I also want to see how big/small an impact this addition would have on the results. I will write the program then, and we'll be able to put your maths into it to replace mine to see how our methods compare. This will help us home in on the truth of the matter, and everyone will be able to see it all in action. Oh, and I've actually cheated by writing half the program in advance, so it may be ready by tomorrow.