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Author Topic: A Question for the mathematitions.  (Read 1161 times)

BFSMP

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A Question for the mathematitions.
« on: July 23, 2017, 05:52:27 PM »


 I am of the old school and always work in imperial measure.


If  a cubic yard of salt water weighs 3/4 of a ton, what would be the estimated colossal weight of salt water  existing on the earth's surface, and at such a colossal weight why does it not crush the earth to a pulp.


I know it  all has to do with gravity but why...a vehicle left in soggy field will eventually bury itself in the soft earth if left long enough because of it's weight, and yet gravity is at work.


Someone please explain to this thick old sod why it does not also bury the earth under the weight of such tremendous force.


Thank you.


Jim.
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raflaunches

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Re: A Question for the mathematitions.
« Reply #1 on: July 23, 2017, 06:15:06 PM »

I think it's due to the fact that the deepest known part of the ocean is about 12-20 miles and the radius of the Earth is 3958.756 miles.
So the outer layer doesn't even weigh a fraction of the entire mass of the planet. I think... %)
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Nick B

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plastic

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Re: A Question for the mathematitions.
« Reply #2 on: July 23, 2017, 06:27:44 PM »

Gravity - at any point on the earth, the heavy stuff has sunk to the bottom - so iron at the bottom, rock above that & water (as the lightest) on the top.
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roycv

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Re: A Question for the mathematitions.
« Reply #3 on: July 23, 2017, 07:18:00 PM »

Hi don't forget that water is used as a reference measurement specific gravity etc.  Most of the numbers for other elements and the like come out > 1.  The rest either float on water or are gases.  So although there seems a lot of it about, going downwards  we only know about the first 15 miles out of nearly 4000 miles.
The water that really does drop down low hits very hot stuff (magma) instantly goes way beyond boiling point and comes up like an express train called a geyser.
Hope that helps,
Roy
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Mark T

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Re: A Question for the mathematitions.
« Reply #4 on: July 23, 2017, 08:04:43 PM »

I've never really understood gravity.  How can something be so powerful that it keeps the worlds oceans in place and yet a butterfly can fly?
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Re: A Question for the mathematitions.
« Reply #5 on: July 23, 2017, 08:11:51 PM »

Ah now you're into the world of aeronautical theory about the equation of lift!
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BrianB6

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Re: A Question for the mathematitions.
« Reply #6 on: July 24, 2017, 12:51:05 AM »

Didn't someone prove that it was impossible for a bumble bee to fly.
The only problem was that he forgot to tell the bumble bees.
Gravity as such is quite a weak force but it acts everywhere as pointed out by Mr. Einstein.
The sea is actually floating on the rocks of the sea bed although it does penetrate it, like rain on your garden until the ground is saturated and forms a pond so that you can sail your boat on it!
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derekwarner

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Re: A Question for the mathematitions.
« Reply #7 on: July 24, 2017, 01:38:00 AM »

So OK Jim.......

This is why when I am spraying grey primer from a rattle can...a fine grey dust settles and ends up on my brown boots...I can accept this, however why does the same grey primer mist also end up on my reading glasses >>:-( when they are say 1 yard away in both height and horizontal distance.... :kiss:

However for the following to be correct...'If  a cubic yard of salt water weighs 3/4 of a ton'...is this in a solid 1 piece rock state as evaporated for the briney......or is this Grade No 55 Table Salt with each grain size of .............1/10,000,000,000 of an imperial cubic yead & also with the equivalent of 0.06247 volume's air space around ach grain? {-)
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roycv

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Re: A Question for the mathematitions.
« Reply #8 on: July 24, 2017, 05:22:32 AM »

Hi Mark T I think that Arthur C Clarke suggested that if one could create a large hangar sized room on the moon and filled with air at our normal pressure then a man could fly with wings attached to arms.  Gravity is about 1/6th. on the moon I believe.
regards Roy
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RAAArtyGunner

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Re: A Question for the mathematitions.
« Reply #9 on: July 24, 2017, 07:59:51 AM »

Hasn't it got to do with equilibrium.

The earth's rotation is what keeps everything in place, in equilibrium.

When man interferes, such as building a structure on the Ground AKA the earth the equilibrium is out of balance and must be corrected by strengthening under the structure AKA footings.

Why does a concrete boat float???
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malcolmfrary

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Re: A Question for the mathematitions.
« Reply #10 on: July 24, 2017, 09:11:15 AM »

Why does a concrete boat float???
Mostly because of the big air hole in the middle, just like a steel ship.  Many otherwise clever people in the early 19th century were of the opinion that iron ships were impossible, never having realized that.


To all intents and purposes, the Earth is a solid sphere.  It is not hollow like a football, despite the imaginative tales of Jules Verne.  Liquids tend not to pass through solids if the solids are truly solids.  That's why earthenware cups are so popular for holding drinks and not making a mess on the table. 
Because there are gaps between the rocks at and near the surface, liquid does seep down because gravity does attract anything and everything that can move, but, as noted previously, when it gets to the hot stuff only a very few miles down, it gets heated and goes no further. 

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Ron Rees

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Re: A Question for the mathematitions.
« Reply #11 on: July 24, 2017, 10:32:20 AM »

My brain hurts!!!(What there is of it)



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dreadnought72

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Re: A Question for the mathematitions.
« Reply #12 on: July 24, 2017, 01:08:25 PM »

Jim, you could ask the same question about the atmosphere. The pressure at the surface is 14.7 psi - a weight equivalent to over ten stone on your palm. So why don't we feel it?


The answer comes from Newton's Third Law - the action and reaction one. My chair has four legs with a base surface area of about 4 square inches. Me and the chair weigh 180lbs: the pressure on the floor is therefore 45psi, about three atmospheres. But the reaction of the floor supporting this force is the same - it must be, the chair's not sinking into the floor. Likewise with your hand - the pressure on all sides is 1atm, but there's a counter pressure of 1atm at the skin due to the (relative) incompressibility of humans.


The car in the boggy field sinks, as the counter pressure of the mud is mechanically not able to support the vehicle's weight (...but it might if the pressure was reduced by spreading the weight over a larger area: give the vehicle tracks to spread the load).


At the bottom of the ocean, where pressures can be over a thousand atmospheres, the waterlogged silts (effectively incompressible) provide a counter-acting supporting force.


Andy
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Bob K

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Re: A Question for the mathematitions.
« Reply #13 on: July 24, 2017, 02:58:07 PM »

If you put water in a container with a small hole in the bottom, due to the aforementioned forces, it will always drain out of the container.   In the special case where water can sometimes get into a model boat, for various reasons, why can't we just drill a small hole in the bottom of the hull so that any water getting in will immediately drain out?  It should work.  Water is heavier than air  %%
Flower pots never fill up with water even in a downpour.  Why?  They have drain holes.

(Just trying to apply the original logic from this thread)
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roycv

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Re: A Question for the mathematitions.
« Reply #14 on: July 24, 2017, 03:20:57 PM »

Pressures dear boy, pressures!
Roy
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plastic

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Re: A Question for the mathematitions.
« Reply #15 on: July 25, 2017, 06:16:07 AM »

On a similar note, If I take a divers watch 30 feet underwater it measures +1 extra atmosphere of pressure.

If I put that watch into a little sealed box with a small diameter pipe out the top that is about 30 feet high and fill it with water, there will only be a few grams (CCs) of water in the vertical tube - so what pressure will the watch display?

A tiny bit more than atmosphere or +1 atmosphere?
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malcolmfrary

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Re: A Question for the mathematitions.
« Reply #16 on: July 25, 2017, 08:30:36 AM »

Provided that the pipe is not so narrow that capillary action comes into play, and that the upper end is open to atmosphere, the same 30 feet.  The watch wouldn't be much use otherwise.
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