what would happen to the metal slab

Google "Trieste". There's even a video documentary, about a half hour long, though I've no idea where to find it.

<LOL> where was I in 1960? I thought the bathyscape never made it to the bottom! I'll try to find the video later.

thanks for answering a dummy's question!

Not a dumb question. If you ever find the video, watch for what happened to the plexiglass.

Compressive forces are large, but not large enough to deform solid steel.

Basic info here... http://en.wikipedia.org/wiki/Mariana_Trench

Saw this program recently... How the Earth Was Made - The Deepest Place on Earth

http://www.history.com/shows.do?action=detail&amp;episodeId=482034

I already knew the basic historical events, but I found the additional details presented both entertaining and educational.

I decided to follow the 2nd link, just starting lunch break, thought it would be a educational Lunch Break

We're sorry, the page you requested could not be found.

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best answer, IMHO. GA there!

It would sink and get wet.
Del

And very, very cold.

Jon

1- temperature is not as low as you think so tha it can only become cold (>0°C) and

2- what if it falls near to a hot source with a temperature over 200°C?

3- as an answer to the "oxigen" problem rust if there are ions H-O then as far as I know rust can develop.

A solid metal will be very slightly compressed, you would have to canculate it from the tables for that length and thickness. It might shrink 1/100 of a percent, really very little, not enough to change the bulk density to make it stable at one depth.

The trieste was a balloon of steel with a flotation "gas" of gasoline,(later kerosine for fire risk) which is a little more compressible than steel, but still virtually incompressible at 35,000 feet..The people were in a steel sphere with special conical windows.

It was ballasted with steel pellets held in place with an electro-magnet powered by a lead acid battery, also in the kerosine. As the electromagnet depletes the battery and the magnetic field drops, the pellets are lost and this made a fail safe auto flotation device.

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

The russian "trieste" is similar, but had a titanium shell for the people, and was thus lighter = smallerI recall in my youth reading about William Beebe, who went down a few thousand feet in a cable hung steel ball. They could not go very deep, as the weight of the cable was a limiting factor as it soon reached it's self supporting weight with the sphere on it, and so they hade to stay away from that limit by some safety factor.

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

It would set there and slowly rust would it not be suspened at around 8700 feet then swept by currents ? Just a quick calcuation in my head.

The Titanic comes to mind even fine glassware was in tact but other thing were cracked where voids inside made it weak but the pressure of the water caused the damage to only that weak area during descent. It is instant not a slow effect.

It's a good question, and it looks like you have the answers(though I haven't checked all the links yet). One thing puzzle me ; "I'm actually planning to use this as an illustration, one day."

Of what ? Do you men in some artistic sense, or are you going to explain this to others in some teaching capacity. Performance art even ? I'm not taking the ****, I can see good potential in all those scenarios.

Seemingly straightforward questions often result in interesting discussion. (Damn, I wish I'd though of this one). I could point you to a bunch of links that relate to the question, but I think people have already covered the bases there. I'm just being a little nosey about your meaning with that phrase,

The only way a steel something could be crushed at that depth was if it were hollow, and the outside pressure was sufficient to crush the object. The steel itself would not be affected by the pressure, and I doubt if there is enough oxygen at that depth in the ocean to rust the steel. Steel plate can be "molded" or formed by explosive charges that far exceed the pressure of the deepest part of the ocean, but those explosive forces only form the steel, they don't "crush" it.

Re: "I doubt if there is enough oxygen at that depth in the ocean to rust the steel."

Please, please, please do not encourage people ... especially in such a fine forum as this ... to perpetuate incorrect thinking...!

That's what 'grandpas' do, when explaining to their offspring that the reason they're stuffing bondo into that hole in their rocker-panel is because it got ate up by 'electrolysis'.

Redox reactions do NOT require oxygen to take place. PERIOD!

Just because the reduction of oxygen is the most common (reduction) reaction in the splash zone (marine environment) doesn't mean that "rusting" wouldn't occur if there were no oxygen.

Since you already know this ... for the sake of the unenlightened, who occasionally frequent this forum FOR enlightenment's sake ... (I humbly suggest) edit all subsequent posts to reflect the full spectrum ~ e.g.: "oxygen content of the water at that depth in the ocean is miniscule, and thus, in the absence of any pollution products that would substitute for reduction-purposes, rusting of the steel would be minimized."

sputter....gasp.....vent.....

Nothing would happen to the metal, except get wet and slowly rust, as there's very little "free" dissolved oxygen in the water at such a great depth. Ummm, let's observe the KISS Principle here folks....

Anyhow, the water pressure would be acting on it from all directions....

.....and we shall chant Sir Isaac Newton over and over again until it's engrained in our meager braincells forever and ever more..... "for every action (in this case force or pressure), there's an equal and opposite reaction".

there's my 2 Cents worth...ain't worth much...can't even buy a Boozoka Joe Bubble Gum for that amount now days...*SIGH*

I remember when I was a kid, my grandmother worked on a NOAA research ship doing work over the trench. She sent us (my siblings and myself) styrofoam coffee cups that had been to the bottom. The immense pressure had forced out all the gasses trapped in the styrofoam, shrinking them down to roughly the size of a shot glass (I'm not sure if they started out as 8, 12, or 16 oz cups). I remember they had the texture of rough plaster.

This "real world" experience leads me to question if in fact nothing would happen to the steel plate, or if it would in actually change shape ever so slightly depending on the quantity and distribution of trapped gasses inside, and possibly even the grain structure of the materials in the metallic plate. Its well known that certain iron alloys change grain structure and composition when exposed to various temperatures and pressures (cast iron being notorious for this).

To recap most of the info already posted...

Bottom of Mariana Trench
http://en.wikipedia.org/wiki/Mariana_Trench

Pressure is 108.6 [MPa]

MPa conversion to PSI
http://www.chapelsteel.com/mpa-psi.html

or 15,751 [PSI]

Yield Strength
http://en.wikipedia.org/wiki/Yield_(engineering)

Even the weakest steel on the list has a yield strength >2x the pressure at the bottom of the Mariana Trench. No permanent deformation should occur to a solid piece of steel.

The bulk modulus (K) of a substance measures the substance's resistance to uniform compression. It is defined as the pressure increase needed to cause a given relative decrease in volume. Its base unit is Pascal.

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

As an example, suppose an iron cannon ball with bulk modulus 160 GPa is to be reduced in volume by 0.5%. This requires a pressure increase of 0.005×160 GPa = 0.8 GPa116,000 psi).

now the Mariana Trench is 35,000 feet or about 1100 atmosphere or about 16,000 PSI, so said bit of steel would get about .07% smaller. Water is 10 times as compressible as steel

Good link to bulk modulus.

Agree with calculation that the volume of said steel cannon ball should decrease ~0.07% at ~16,000 psi.

Follow-up question:

Doesn't it return to its original volume once returned to the surface?

I am not sure if the iron cannonball would expand back to its former size, or if some shear event might occur due to crystal slip etc that may even make it larger or cause a crack or 2 on the way down or up?

I really expect better answers than this.....

.... a slab of metal of any grade? and we don't get anything more exciting than 'sink', 'get wet', 'rust'.....

... ok, this one requires a little luck. drop a solid slab of 3/2.5 titanium ... hydrogen embritlement accelerates as depth increases, extreemly cold temperature, high pressure and hard rock at the bottom causes it to fracture..... the loud sound sends Greenpeace into a panic.

....i like this one more..... one ton of Sodium, pure. dropped into the ocean. ..........highly unlikely that one makes it even 1 mile down.

benbenben

COME ON, I bet you guys can think of some more....

Hello langyaw,

Almost needless to say; the Ton of metal will always be more dense than the sea water. So not much will happen to it other than it going rusty and maybe fish and or wave action will wear away at the rust until the metal is gone. But, that will not be for perhaps 300 or 400 hundred years. Interesting though.

Take care