Thread: Re Alex Euler & test Question

I am interested in what the answer to the question is, ...The q was something like "how long would a piece of iron or steel ex dimensions - size of a continent - take to sink into the ocean?"
Mr Euler said he gave clues, one which I think was the "ship crew."
I asked a friend who is a ship driver for super tankers to China, he said that it is impossible to dock a tanker in some places where the dock has a wall down to sea level, and that even with powerful screws at the front and back of the tanker, designed to push the ship sideways into the dock, you cannot get any closer than about three meters.
When asked why, he said that the water acts like a cushion and can not get out of the way. I asked what it would take to bring the ship in, and he said not even winches and cranes can help. the dock has to be designed to let water out quickly...I think the q may have been a trick q, because there is no "how long" it takes...it does not sink, the amount of water that has to be diverted is far too great.
Euler also said that Robitty was close to the answer, I think one of the replies was about a razor floating on water?But water tension would not work...So the iron world on the sea would be like leaving your footprint in wet concrete, but not sinking in...The answer could have been called "displacement" ?

Possibly. I thought of the same answer later on.
Whatever the answer is it should be something that negates the idea of the steel raft sinking because Euler indicated there was a unique answer and it seems there are too many variables in the sinking scenario to give one unique answer to the question.

It is to bad he was posing the question as a troll.

The problem with using "displacement" to claim that it wouldn't reach the bottom is spurious.
A dock is a local and essentially contained body of water [sup1[/sup]. The Pacific Ocean isn't.
There are plenty of ways for the water to be moved "aside" either by raising its own level or by pushing the "excess" into other oceans.
In fact it would be a combination of these - water would be displaced into other oceans and the level of ALL raised.


1 "I asked a friend who is a ship driver for super tankers to China, he said that it is impossible to dock a tanker in some places where the dock has a wall down to sea level, and that even with powerful screws at the front and back of the tanker, designed to push the ship sideways into the dock, you cannot get any closer than about three meters." I've just Googled and nothing has come up so I'll stick with my own thoughts here. I find this somewhat hard to believe. Water is a liquid that is, for all practical purposes, incompressible. In order to make such a "cushion" it would have to NOT flow. Even in a contained area it has the opportunity to flow around/ away the "entrapment" AND (if very locally "trapped") rise higher than the general level. I'm gonna have to give a resounding "Nope" to this "solution" unless new evidence comes along.

If some water became trapped between the ship and dock, it could seem like a cushion because when the screws are running, the water level would rise between ship and dock, then if you shut the screws off, the water would tend to push the ship away. As Dywyddyr points out, the dock would not cut off all flow, but if it's tight enough, it might seem "impossible" to dock, just because it takes longer than the ship driver expected.

I'm not losing any sleep over the loss of Alex's knowledge.

I have thought about it and talked with a couple of physicists, while I am not educated in any field of science above high school level, I am intrigued.
In regards to the behavior of material on larger scales, the point was made to me that, if you had a pendulum, a weight on a string, that the longer the string the slower it will oscillate...until it is completely stationary...which mathematically and theoretically can only be a string of infinite length. But for your own observational experiment, the string does not have to be infinitely long, but only long enough to make it practically stationary...which is not that long at all.
The other illustration told, was if we had a set length of the string -lets say 100 m... and we increased the weight until it stopped swinging, it too would not have to be infinitely heavy, far from it...there is a point in both examples, very early in the equation where the relationship between the string and weight is no longer of any consequence...?
So they said that with displacement , you would only need a piece of steel 320 or so km across for it not to sink, and remain afloat for practically such a long time that you'd be dead by the time it started to sink...and if any larger it cannot sink, because the water can not be dispersed quick enough to have any effect.
The whole idea seems preposterous because we are used to the glass of water spilling on the table, and all of our concepts never get any bigger than a beach scene...
On that point I have noticed that if we take a proportionate section of water, let's say ten times longer than deep, and make a wave one tenth of the depth...and if we increase the overall size of this experiment, starting from a 1 meter length of water, we find that the wave runs from one end to the other in about 2 seconds, this time increases with proportionate size, so that a ten km distance takes how long? 100 km longer, 1000 km hours or even days maybe? But I would have thought that the increased energy required to generate greater waves, increases exponentially? in the same way that volume increases in multiples of area? And maybe the energy required to displace water ends up being greater than the downward force of the steel plate? Does that make any sense?

Originally Posted by Starhunter

I have thought about it and talked with a couple of physicists, while I am not educated in any field of science above high school level, I am intrigued.
In regards to the behavior of material on larger scales, the point was made to me that, if you had a pendulum, a weight on a string, that the longer the string the slower it will oscillate...until it is completely stationary...which mathematically and theoretically can only be a string of infinite length. But for your own observational experiment, the string does not have to be infinitely long, but only long enough to make it practically stationary...which is not that long at all.
The other illustration told, was if we had a set length of the string -lets say 100 m... and we increased the weight until it stopped swinging, it too would not have to be infinitely heavy, far from it...there is a point in both examples, very early in the equation where the relationship between the string and weight is no longer of any consequence...?
So they said that with displacement , you would only need a piece of steel 320 or so km across for it not to sink, and remain afloat for practically such a long time that you'd be dead by the time it started to sink...and if any larger it cannot sink, because the water can not be dispersed quick enough to have any effect.
The whole idea seems preposterous because we are used to the glass of water spilling on the table, and all of our concepts never get any bigger than a beach scene...
On that point I have noticed that if we take a proportionate section of water, let's say ten times longer than deep, and make a wave one tenth of the depth...and if we increase the overall size of this experiment, starting from a 1 meter length of water, we find that the wave runs from one end to the other in about 2 seconds, this time increases with proportionate size, so that a ten km distance takes how long? 100 km longer, 1000 km hours or even days maybe? But I would have thought that the increased energy required to generate greater waves, increases exponentially? in the same way that volume increases in multiples of area? And maybe the energy required to displace water ends up being greater than the downward force of the steel plate? Does that make any sense?

Let's see the calculation.
no, that last part doesn't make sense because energy is different than force so you cannot compare the two.

That is a scary thought.
Pendulum (mathematics) - Wikipedia, the free encyclopedia

Originally Posted by dan hunter

That is a scary thought.

Harold, I am obviously not aware of the correct terms energy/force, but you get the drift?

Dan,
...it is a scary thought, to think that water on a large scale behaves more like a solid than a liquid.

IIRC, viscosity decreases as scale increases, which means that at large scales, rock tends to behave more like water rather than the other way around. (This comes up when dealing with meteor strikes, for example.)

Originally Posted by Starhunter

and we increased the weight until it stopped swinging, it too would not have to be infinitely heavy, far from it.

No, you're confusing two different things.
The period (time of swing) of a pendulum is entirely independent of the weight. Thus, you cannot conflate "not swinging due to weight of bob" with "length of the pendulum".
One reason why a very heavy pendulum wouldn't swing is that the larger the weight the more force is required to start the swing (and, strictly speaking, unless one was extremely careful it's almost impossible to set up a pendulum with zero swing - but that swing may be so small in amplitude that it's all but undetectable).

So they said that with displacement , you would only need a piece of steel 320 or so km across for it not to sink, and remain afloat for practically such a long time that you'd be dead by the time it started to sink...and if any larger it cannot sink, because the water can not be dispersed quick enough to have any effect.

I'd be interested in the calculations involved. I find this hard to credit.

But I would have thought that the increased energy required to generate greater waves, increases exponentially?

Displacing water isn't the same as making waves.

Originally Posted by MagiMaster

IIRC, viscosity decreases as scale increases, which means that at large scales, rock tends to behave more like water rather than the other way around. (This comes up when dealing with meteor strikes, for example.)

The rock bit is true, the earth is flexible. Same as the iron continent, would bend to the ocean's profile, which can vary up to 60 meters between continents...from what I have heard. About water, I can only go by what I was told...I think that the comparative behavior of water on a small scale to large, would make the water seem less able to flow on a large scale?

Originally Posted by Dywyddyr

Originally Posted by Starhunter

and we increased the weight until it stopped swinging, it too would not have to be infinitely heavy, far from it.

No, you're confusing two different things.
The period (time of swing) of a pendulum is entirely independent of the weight. Thus, you cannot conflate "not swinging due to weight of bob" with "length of the pendulum".
One reason why a very heavy pendulum wouldn't swing is that the larger the weight the more force is required to start the swing (and, strictly speaking, unless one was extremely careful it's almost impossible to set up a pendulum with zero swing - but that swing may be so small in amplitude that it's all but undetectable).

So they said that with displacement , you would only need a piece of steel 320 or so km across for it not to sink, and remain afloat for practically such a long time that you'd be dead by the time it started to sink...and if any larger it cannot sink, because the water can not be dispersed quick enough to have any effect.

I'd be interested in the calculations involved. I find this hard to credit.

But I would have thought that the increased energy required to generate greater waves, increases exponentially?

Displacing water isn't the same as making waves.

I would not know anything about that, the only thing I know about pendulums is the old clock Pop had, if you want the clock to slow down, you move the weight down to give a longer arm. And the water...making waves, displacing, changing direction of flow, any change to the body of water requires forces proportionate to its mass...don't you think? I am not science trained, so if I hear the lynch mob coming I'm out of here!

Originally Posted by Starhunter

Originally Posted by MagiMaster

IIRC, viscosity decreases as scale increases, which means that at large scales, rock tends to behave more like water rather than the other way around. (This comes up when dealing with meteor strikes, for example.)

The rock bit is true, the earth is flexible. Same as the iron continent, would bend to the ocean's profile, which can vary up to 60 meters between continents...from what I have heard. About water, I can only go by what I was told...I think that the comparative behavior of water on a small scale to large, would make the water seem less able to flow on a large scale?

Why? It has more room to get out of the way and the relative particle size is smaller. It might take longer to move a proportional distance, but that's not the same thing.

Originally Posted by Starhunter

.....
Euler also said that Robitty was close to the answer, I think one of the replies was about a razor floating on water?But water tension would not work...So the iron world on the sea would be like leaving your footprint in wet concrete, but not sinking in...The answer could have been called "displacement" ?

That comment about wet concrete is not entirely true. It happened to me once where I was pouring the footing for this signage and the concrete truck had just delivered the concrete mix and a client to my surprize walked straight across the wet concrete and sunk into it up to her hip.
If the concrete is drier and a little more set it will perform as you say.

Originally Posted by MagiMaster

Why? It has more room to get out of the way and the relative particle size is smaller. It might take longer to move a proportional distance, but that's not the same thing.

That's what I mean -proportionately. We could go the other way to make it easier to think about. If you were as tall as a figure that fits into a matchbox car, and you stood next to bottle lid filled with water above the brim and held by water tension, you would have a half a meter bulge of water above the edge of the lid. -by comparison that is. Or if you had a drop of water on the table, it would be like a piece of jelly. That's water tension, and of course nothing to do with up scaling, but, just to illustrate that scaling can change apparent behavior... So going back to large scale, if you were a giant, say as tall as the golden gate bridge, and you hit the water with your hand, it would not give way that easily, but it would be like hitting concrete...right?
If you have ever walked through water up to the waist, you know its pretty hard to move along quickly, now if you scaled that up to the size of our giant, he would find it even more difficult, and would travel at only a quarter of the speed -proportionately.
Now up size the giant to about 5000 feet tall and make him walk waist deep in the ocean, he will not be able to move...? does that answer the concrete thing - Robittybob?

Originally Posted by Starhunter

Originally Posted by MagiMaster

Why? It has more room to get out of the way and the relative particle size is smaller. It might take longer to move a proportional distance, but that's not the same thing.

That's what I mean -proportionately. We could go the other way to make it easier to think about. If you were as tall as a figure that fits into a matchbox car, and you stood next to bottle lid filled with water above the brim and held by water tension, you would have a half a meter bulge of water above the edge of the lid. -by comparison that is. Or if you had a drop of water on the table, it would be like a piece of jelly. That's water tension, and of course nothing to do with up scaling, but, just to illustrate that scaling can change apparent behavior... So going back to large scale, if you were a giant, say as tall as the golden gate bridge, and you hit the water with your hand, it would not give way that easily, but it would be like hitting concrete...right?
If you have ever walked through water up to the waist, you know its pretty hard to move along quickly, now if you scaled that up to the size of our giant, he would find it even more difficult, and would travel at only a quarter of the speed -proportionately.
Now up size the giant to about 5000 feet tall and make him walk waist deep in the ocean, he will not be able to move...? does that answer the concrete thing - Robittybob?

If the big plate was dropped or say gently lowered into the Pacific ocean in an area free of Islands I believe it would sink to a depth determined by its density quite rapidly and then the effects you speak of take over, but I do believe it will sink. But, as described, when it was closer to the bottom it will be supported by a cushion of water that will take a long time to touch the bottom. But the bottom isn't going to be totally flat so this cushion won't be as effective as you imagine.

Originally Posted by Starhunter

Harold, I am obviously not aware of the correct terms energy/force, but you get the drift?

No. The iron is denser than water, so it would exert a greater force than the force due to water pressure underneath. That's why iron sinks.

Obviously if the iron is to move through the water, then the water has to get out of its way.

So how long would it take for one liter of water to make it from the center of the iron sheet to the edge of the sheet to the edge of the sheet?
I suppose there would have to be an allowance time delay because of friction between the water and the steel sheet, and for sheering in the water itself.

I hope somebody with the engineering background can give an answer.

If the huge metal sheet follows the curvature I am wondering how the water at the centre of the curvature is expelled at all.......*scratches head some more*

Originally Posted by Implicate Order

If the huge metal sheet follows the curvature I am wondering how the water at the centre of the curvature is expelled at all.......*scratches head some more*

The water follows the same curvature though so all of the curvature effects should cancel, unless I am missing something we could just assume both the water and sheet of iron are flat against each other.

Originally Posted by Implicate Order

If the huge metal sheet follows the curvature I am wondering how the water at the centre of the curvature is expelled at all.......*scratches head some more*

The water right underneath the plate doesn't have to go anywhere except down. It will push aside the water underneath it, but the ocean is pretty deep, so I don't see the flow being restricted much at all.

Originally Posted by Harold14370

Originally Posted by Implicate Order

If the huge metal sheet follows the curvature I am wondering how the water at the centre of the curvature is expelled at all.......*scratches head some more*

The water right underneath the plate doesn't have to go anywhere except down. It will push aside the water underneath it, but the ocean is pretty deep, so I don't see the flow being restricted much at all.

If it trapped too much underneath it could be face with much inertia. So it will be slowed but it won't be stopped. I agree with Harold.

Originally Posted by Starhunter

Originally Posted by MagiMaster

Why? It has more room to get out of the way and the relative particle size is smaller. It might take longer to move a proportional distance, but that's not the same thing.

That's what I mean -proportionately. We could go the other way to make it easier to think about. If you were as tall as a figure that fits into a matchbox car, and you stood next to bottle lid filled with water above the brim and held by water tension, you would have a half a meter bulge of water above the edge of the lid. -by comparison that is. Or if you had a drop of water on the table, it would be like a piece of jelly. That's water tension, and of course nothing to do with up scaling, but, just to illustrate that scaling can change apparent behavior... So going back to large scale, if you were a giant, say as tall as the golden gate bridge, and you hit the water with your hand, it would not give way that easily, but it would be like hitting concrete...right?
If you have ever walked through water up to the waist, you know its pretty hard to move along quickly, now if you scaled that up to the size of our giant, he would find it even more difficult, and would travel at only a quarter of the speed -proportionately.
Now up size the giant to about 5000 feet tall and make him walk waist deep in the ocean, he will not be able to move...? does that answer the concrete thing - Robittybob?

I don't think that's right.

The meniscus of water over the edge of a container will become proportionally smaller as the size of the container increases. Similarly a drop sitting on a surface will become proportionally flatter.

At the same time, the meniscus will become smaller if you use a less viscous (runnier) fluid and drops of less viscous fluid will become flatter.

A giant walking in to water would find moving much easier than a human, just like a human finds in much easier than an insect.

Magimaster, Have you ever seen an ant get stuck head first in a water droplet? If you were that small the same would occur...that's what I meant, I may have said it wrong.
About the ship docking, I asked my uncle again...the screws of the ship are not pushing the water towards the dock wall, but pulling it away, Harold, and when the ship came closer to the wall, the water would rise up by about a meter, and my uncle expected to see the water rush towards the back and front of the vessel, but there was no sign of movement, except a gradual decline in the water level from the edge of the ship to sea level, even though the pressure was on for 5 to 10 minutes. Apparently the water can not get away fast enough, and "does not seem to care about a bulge on the surface, in the same way it does not care how big other waves get on its surface." My uncle also said that the bigger the wave or body of water the slower it moves. A ripple can come and go in less than a second, but waves, even when they are not traveling, just bobbing up and down, take up to 30 seconds to rise and fall...
I guess the problem with this whole question is that we keep reverting back to our known experiences and perceptions of water...the denser iron, the splash in the pool...and then use science of those activities to prove it...for the steel not to sink just seems illogical.
From what you have all posted, I agree with you all because I can see it both ways, naturally imagining it sinking, but something tells me it can defy small scale 'logic' in the same way that the atmosphere is softer than a feather and yet it can cause an asteroid to bounce off the earth ere it meets the ground, or break it into pieces as if it were as hard as tempered glass...? Which is another thing possibly not related, but I am talking in the sense of how things on a large scale can defy small scale observations...

There are several things you all added, the problem of moving water from center to outside, the curvature or bulges in the water level that need to be moved, the water down below it is not compressed, and will not flow downwards...cannot go sideways in a hurry, the changing shape of the plate with the general water, ...then I thought that if all or some of the water that has to be displaced is caused to move from center outwards, that's a lot of water !, it would have to occur simultaneously...more or less, and if there are ocean currents, they would ruin that process, because it will be impossible to change the flow speed and direction of a whole ocean, then we also have the centrifugal force of the plate away from the center of the earth...no that would not count, because the ocean has the same force, both overruled by gravity...what about tidal pull? ...And what about the fact that all the water in the oceans is attracted downwards by gravity and that its relation to water levels on the other side of the earth or hundreds of miles away is insignificant? So the tendency of water is to "sit down" rather than flow east west or elsewhere, and the forces required to move it sideways, are possibly not available?... But I suppose these conditions were not in the Q... As Dywyddyr said, there are a lot of other factors.

Originally Posted by Starhunter

About the ship docking, I asked my uncle again...the screws of the ship are not pushing the water towards the dock wall, but pulling it away,

Yes but the ship is pushing water ahead of it toward the dock, which is what causes the water to rise a meter high.

Harold, and when the ship came closer to the wall, the water would rise up by about a meter, and my uncle expected to see the water rush towards the back and front of the vessel, but there was no sign of movement, except a gradual decline in the water level from the edge of the ship to sea level, even though the pressure was on for 5 to 10 minutes. Apparently the water can not get away fast enough, and "does not seem to care about a bulge on the surface, in the same way it does not care how big other waves get on its surface."

I think this agrees with what I said before. The equalization takes a lot longer than your uncle expects. But that is because of the flow restriction created by the ship's hull being close to the dock. There is no such restriction to the flow out in the middle of the ocean.

My uncle also said that the bigger the wave or body of water the slower it moves. A ripple can come and go in less than a second, but waves, even when they are not traveling, just bobbing up and down, take up to 30 seconds to rise and fall...

That's what you would expect since it has farther to go to rise and fall.

Originally Posted by Starhunter

Magimaster, Have you ever seen an ant get stuck head first in a water droplet? If you were that small the same would occur...that's what I meant, I may have said it wrong.

Yes, that's because at that scale water is more viscous and harder to move around in. At our scale, it's less viscous and easier to move. At larger scales, it'd be even less viscous and even easier to move.

Also, I don't think anyone here actually thinks the steel plate would float. The questions are more about how long it'd take to sink.

Originally Posted by MagiMaster

Also, I don't think anyone here actually thinks the steel plate would float...

That just about sums it up...

Originally Posted by Starhunter

Originally Posted by MagiMaster

Also, I don't think anyone here actually thinks the steel plate would float...

That just about sums it up...

The original question asked how long it'd take to sink. Assuming it sank at all (which seems like a safe assumption), the calculations of how long it'd take would be very complex even for overly simplified versions of the problem. And you can't just test the problem in small scale since things like area, volume and viscosity don't all scale together.

Originally Posted by Starhunter

Originally Posted by MagiMaster

Also, I don't think anyone here actually thinks the steel plate would float...

That just about sums it up...

Except for me because I am moonbat crazy!!!

Originally Posted by dan hunter

Except for me because I am moonbat crazy!!!

Absolutely liked your input, you're definitely not crazy, while I concede that most believe it will sink, according to Euler's hint - that it does not take calculations on how long it will take to sink, it does not sink, and I am keeping that in mind...just in case.

I looked at the full math on pendulums.
It is a bit counterintuitive.
We oversimplify them when we use the narrow angle approximation. The full equations are very difficult to solve, but they include the fact that pendulums are not perfectly isochronic.
Your friends were right about the result being an infinite period when the length of the pendulum is infinite.

is a fairly good approximation though not exact.

Originally Posted by dan hunter

I looked at the full math on pendulums.
It is a bit counterintuitive.
We oversimplify them when we use the narrow angle approximation. The full equations are very difficult to solve, but they include the fact that pendulums are not perfectly isochronic.
Your friends were right about the result being an infinite period when the length of the pendulum is infinite.

is a fairly good approximation though not exact.

So the length of the pendulum does not have to be infinite, only long enough to create the 'effect' of not swinging at all...? I would not be surprised how short it can be. By slow I mean like watching the grass grow, or the speed of the midday shadow on the sundial.

To illustrate the 'reluctance' of the oceans to level out, there are places in the ocean which are consistently higher above sea level, by as much as 60 meters, and yet the water does not even out. Ocean currents probably cause some of that, and the other I assume is that every section of water has its prime relation towards the earth by gravity, but its side movement is restricted by the water next to it and so on, over thousands of kilometers, then the water in the middle of the plate has no where to go until everything else moves first, and then this depends on very great forces, I imagine, to get the ocean or any part of it to move.
I guess most people do not obsess about how things work, and their ideas are restricted to whatever they have experienced...so to say that the ocean has high bulges of water that never level out, or that it nigh impossible to change the direction of an ocean current, or that great waves take hours to settle, even after the wind stops, is just a pack of lies...because their bath tub learning is positive proof. Hollywood movies on world disasters have only recently begun to give credit to these facts...but years ago we could watch star wars and hear the explosions in empty space?, or from the 50's, see men fighting giant ants, which on that scale could not move, ...watch a scaled down ship on a model stormy ocean, moving up and down so fast that everybody on deck would be instantly killed..and so on. I notice from an aircraft when landing near beaches, I have never heard anybody say, look at them waves moving, because as far as we are concerned they are practically stationary...and we are only talking about a distance of action over a length 1/4000th of the theoretical steel plate...sorry for the l-o-n-g post. And thanks for the equation..!

Originally Posted by Starhunter

To illustrate the 'reluctance' of the oceans to level out, there are places in the ocean which are consistently higher above sea level, by as much as 60 meters, and yet the water does not even out.

Citation needed.

Citation needed.[/QUOTE]

1-Mean Sea Level, GPS, and the Geoid

From memory, different articles I have come across, have estimations and measurements of ocean level differences between regional areas- ie, between Australia and NZ, between 20 and 45 m, other ocean areas Pacific and Atlantic 60 - 90 m. Some of these differences in the oceans are practically permanent. And not necessarily always due to current, tides etc...The bathtub experienced observers have declared these to be false, lying, trolling and worthy of an immediate and eternal ban.

Originally Posted by Starhunter

The bathtub experienced observers have declared these to be false, lying, trolling

Citation needed.

Originally Posted by Starhunter

....
To illustrate the 'reluctance' of the oceans to level out, there are places in the ocean which are consistently higher above sea level, by as much as 60 meters, and yet the water does not even out. Ocean currents probably cause some of that, and the other I assume is that every section of water has its prime relation towards the earth by gravity, but its side movement is restricted by the water next to it and so on, over thousands of kilometers, then the water in the middle of the plate has no where to go until everything else moves first, and then this depends on very great forces, I imagine, to get the ocean or any part of it to move.

I think you are going a bit the wrong way here. Most of the ocean bulges are the result as you said of currents piling up and of differencecs in atmospheric pressure over the water.
I could dig out a text called Exploring The Oceans by Henry S Parker, it goes into a bit of detail on the effects of the coriolis forces and gravity regarding this.
It does not have so much to do with water resisting sideways motion in itself.

However you pointed out earlier about the water piling up between a ship and a wharf, but everybody thought just about the effect in the length of a ship.
Even then they acknowledged the ship might be very difficult to winch into the warf.
A ship is usually less than 1 kilometer long, and draws less than a kilometer of depth.
Eulers plate had an area of 4,000,000 kilometers.

For Euler's plate to reach the ocean's floor all of the water under it has to move aside. Without even considering lateral resistance from water surounding the plate, or the piling up from the resulting currents, what kind of forces are we looking at to produce a reasonable movement of the water from under the plate?
Say one kilo of water from the center of the plate to the edge.

Maybe an engineer could tell us.

Originally Posted by dan hunter

I think you are going a bit the wrong way here. Most of the ocean bulges are the result as you said of currents piling up and of differencecs in atmospheric pressure over the water.

I think the article attributed it to differences in gravity because of density of the magma at various parts of the globe.

I could dig out a text called Exploring The Oceans by Henry S Parker, it goes into a bit of detail on the effects of the coriolis forces and gravity regarding this.
It does not have so much to do with water resisting sideways motion in itself.

However you pointed out earlier about the water piling up between a ship and a wharf, but everybody thought just about the effect in the length of a ship.
Even then they acknowledged the ship might be very difficult to winch into the warf.
A ship is usually less than 1 kilometer long, and draws less than a kilometer of depth.
Eulers plate had an area of 4,000,000 kilometers.

For Euler's plate to reach the ocean's floor all of the water under it has to move aside.

Wait a bit. I thought the question was how long it takes to sink, which I think means to go underwater.

Without even considering lateral resistance from water surounding the plate, or the piling up from the resulting currents, what kind of forces are we looking at to produce a reasonable movement of the water from under the plate?
Say one kilo of water from the center of the plate to the edge.

Maybe an engineer could tell us.

Originally Posted by Harold14370

Wait a bit. I thought the question was how long it takes to sink, which I think means to go underwater.

Mmm, that does change the concept a bit.
Now you only have to consider how long it takes to sink 100 meters, just until the top surface is awash.

Originally Posted by dan hunter

Originally Posted by Harold14370

Wait a bit. I thought the question was how long it takes to sink, which I think means to go underwater.

Mmm, that does change the concept a bit.
Now you only have to consider how long it takes to sink 100 meters, just until the top surface is awash.

I would have thought the conditions given - average depth of 3,000 meters with a level ocean basin - were an indicator that "sinking" meant "to the bottom".

Originally Posted by Dywyddyr

Originally Posted by dan hunter

Originally Posted by Harold14370

Wait a bit. I thought the question was how long it takes to sink, which I think means to go underwater.

Mmm, that does change the concept a bit.
Now you only have to consider how long it takes to sink 100 meters, just until the top surface is awash.

I would have thought the conditions given - average depth of 3,000 meters with a level ocean basin - were an indicator that "sinking" meant "to the bottom".

No a ship sinks long before it has hit the bottom. Harold is correct. I'd say sunk to the bottom otherwise.

So, what relevance might the depth of the water have if it is not to calculate an impact time at the ocean floor?
It is 30 times the thickness of the slab of steel.
It kind of reminds me of foundations and the idea of how they create pressure bulbs in the soil, but I doubt if it is relevant that way.

Anyhow, I am still willing to act as a contrarian and claim it stays on the surface. I know it contradicts common sense but common sense is not always the best guide to real world phenomena and is almost never the best guide when dealing with trick question hypotheticals.

If there actually is an answer to the question it should be a fairly simple one to calculate. Euler did hint that it could be done without heavy duty calculations.