Air Pressure vs Gravity

I saw you PM. I'm just slacking and it' hard to respond on a phone.

Quote from: sokarul on January 23, 2017, 06:30:00 PM

False. Newton said gravity was a force. A force cannot act on light. A force would also lead to different masses falling at different rates.

Slight correction. On earth, the effects of Newtonian Mechanics (Laws of Motion and Gravitation) are virtually indistinguishable from GR.

I never claimed otherwise.

Newtonian Gravitation would cause light to bend around extremely massive objects, but only half as much as GR (as GR includes time dilation). Newton himself predicted it as he believed in the corpuscular theory of light - not so far off photons!

I never herd that. I just don't know what formula he would use as the ones I'm aware of can't handle massless particles. I guess he could have given light a mass.

And finally, Newtonian Gravitation causes a force proportional to mass, ie an acceleration.

But he still called it a force. Forces can ultimately be felt, but none are felt.

Don't write old Sir Isaac's mechanics off yet, it is what is used for almost all calculations, even in orbital mechanics - GR is too complicated to use when not absolutely necessary.
GR shows the range of applicability of Newton's Laws (v << c and mass "not too massive") and provides a correction term where necessary.

I agree you can use Newtonian physics in many cases, practically all that would come up in a normal day.

In most cases, time dilation is the first significant effect, simply because time can be measured so precisely.

Keep GR for cosmic scale and particle accelerator problems.

Maybe. I'm hoping to catch gravitation lensing around the moon come the total solar eclipse in august.

Apparently he doesn't realize that sometimes you want to know the displacement with the air trapped inside.  Comes in handy for all sorts of things like rubber duckies and ballistic missile submarines.

Why would you want to know the displacement with the air trapped inside, unless it was ON top of the water and not in?


Let's put this simply.
If an object is ALLOWED to naturally sink then it sinks b y the displacement of its own dense mass by being squeezed down.
If the object is allowed to be sealed with atmosphere then it requires a FORCE to push it down, UNLESS a dense mass is added to it to FORCE out the atmosphere inside which allows the squeeze down.
If not, it gets squeezed up.
It still displaces water but squeezing up is classed as buoyancy.

So here's a question.

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

Before you harp on about buoyancy and what not, just think about what's really happening.

I have a simple experiment for you Scepti. Get a 5 gallon bucket and fill it half to two-thirds full of water. Get a large, hollow plastic cube and a smaller solid, such as a rock or piece of metal. Submerge each item and mark how much water is displaced. Since the rock is more dense than the plastic cube it should displace more water according to your theory. Please post your honest results.

The plastic cube displaced much less water than the rock. Try it yourself.

The plastic cube didn't sink by it's own push, it just displaced it's own mass against the atmosphere which pushed back onto it to create the water displacement in the smaller amount.

The rock displaced it's own mass against the atmosphere which was enough to push it under by the squeeze down effect I mentioned earlier.

I noticed as the rock was sitting at the bottom of the tank, it was giving off the odd rising bubble.
Guess what this was?

This was the pressure of the water squeezing the rock and forcing out trapped atmosphere.
Imagine if the tank was much deeper?

You see, what we're really dealing with, in reality, is, denpressure, which is the displacement of atmospheric pressure by any dense mass.
The reason why this happens is the reason we can actually measure it on a man made scale  and convert it to a weight measurement for us to understand.

Now the only way to measure the density of an object is by all of that dense mass pushing against the atmosphere and resisting the push back of that atmosphere back onto it's own mass by resisting against it by using a solid foundation.
That could be the solid ground or a solid plate on that solid ground that could be compressed down to read a measurement.

You could say that the entire volume of the object is displacing the atmosphere but it's not quite true.
Why?
Because the atmosphere will also be a part of that volume which basically negates the push against it by creating a neutral force.

Now imagine putting a dense object on a floating scale plate on the water?
What would happen?
It's clear that the dense object will do exactly what I explained above but there's a problem.
The scale plate doesn't have a solid foundation to resist the atmospheric push back onto the dense objects resistance of it, so it sinks. It's pushed under the water and so cannot give a true reading.

So here's a question.

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

Answer: The boat.

If you take a cube of metal 10cm x 10cm x 10cm, or 1000cm^3.
Then drop it in to water it will displace 1000cm^3 or 1 litre. This will weigh very nearly 1 kilogram.

Now if you fashion the entire metal cube into a boat form and place it in the water it will displace a different volume, and subsequently a different weight of water depending on the metal.
Magnesium will displace about 1.74l
Steel about 7.5l
Copper about 8.93l
Lead about 11.34
Gold about 19.32l
Tungsten about 19.60l

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

Assuming that the cube sinks, then the boat would displace more water than the cube.

As a boat, the metal displaces an amount of water equal to its own weight. As a cube that has sunk it displaces an amount of water equal to its volume. Since the density of the metal is greater than that of water (known because the cube sinks), then the first amount is greater than the second.

Quote from: markjo on January 24, 2017, 11:37:04 AM

Apparently he doesn't realize that sometimes you want to know the displacement with the air trapped inside.  Comes in handy for all sorts of things like rubber duckies and ballistic missile submarines.

Why would you want to know the displacement with the air trapped inside, unless it was ON top of the water and not in?

Maybe the occupants of a submarine want to know how much breathable air they have when they're underwater.

Let's put this simply.
If an object is ALLOWED to naturally sink then it sinks b y the displacement of its own dense mass by being squeezed down.
If the object is allowed to be sealed with atmosphere then it requires a FORCE to push it down, UNLESS a dense mass is added to it to FORCE out the atmosphere inside which allows the squeeze down.
If not, it gets squeezed up.
It still displaces water but squeezing up is classed as buoyancy.

So here's a question.

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

I've already told you a few times:

If the object is just floating, then it displaces its weight of water.  If the object is completely submerged, then it displaces its volume of water.

I really don't understand why that's so confusing.

Before you harp on about buoyancy and what not, just think about what's really happening.

I have thought about it.  Floating and submerged are two different conditions and therefore different different amounts of water are displaced for different reasons.

Quote from: Albert Wesker on January 25, 2017, 07:54:45 AM

I have a simple experiment for you Scepti. Get a 5 gallon bucket and fill it half to two-thirds full of water. Get a large, hollow plastic cube and a smaller solid, such as a rock or piece of metal. Submerge each item and mark how much water is displaced. Since the rock is more dense than the plastic cube it should displace more water according to your theory. Please post your honest results.

The plastic cube displaced much less water than the rock. Try it yourself.

The plastic cube didn't sink by it's own push, it just displaced it's own mass against the atmosphere which pushed back onto it to create the water displacement in the smaller amount.

The rock displaced it's own mass against the atmosphere which was enough to push it under by the squeeze down effect I mentioned earlier.

I noticed as the rock was sitting at the bottom of the tank, it was giving off the odd rising bubble.
Guess what this was?

This was the pressure of the water squeezing the rock and forcing out trapped atmosphere.
Imagine if the tank was much deeper?

You see, what we're really dealing with, in reality, is, denpressure, which is the displacement of atmospheric pressure by any dense mass.
The reason why this happens is the reason we can actually measure it on a man made scale  and convert it to a weight measurement for us to understand.

Now the only way to measure the density of an object is by all of that dense mass pushing against the atmosphere and resisting the push back of that atmosphere back onto it's own mass by resisting against it by using a solid foundation.
That could be the solid ground or a solid plate on that solid ground that could be compressed down to read a measurement.

You could say that the entire volume of the object is displacing the atmosphere but it's not quite true.
Why?
Because the atmosphere will also be a part of that volume which basically negates the push against it by creating a neutral force.

Now imagine putting a dense object on a floating scale plate on the water?
What would happen?
It's clear that the dense object will do exactly what I explained above but there's a problem.
The scale plate doesn't have a solid foundation to resist the atmospheric push back onto the dense objects resistance of it, so it sinks. It's pushed under the water and so cannot give a true reading.

Please post the video.

Quote from: Albert Wesker on January 25, 2017, 07:54:45 AM

I have a simple experiment for you Scepti. Get a 5 gallon bucket and fill it half to two-thirds full of water. Get a large, hollow plastic cube and a smaller solid, such as a rock or piece of metal. Submerge each item and mark how much water is displaced. Since the rock is more dense than the plastic cube it should displace more water according to your theory. Please post your honest results.

The plastic cube displaced much less water than the rock. Try it yourself.

The plastic cube didn't sink by it's own push, it just displaced it's own mass against the atmosphere which pushed back onto it to create the water displacement in the smaller amount.

The rock displaced it's own mass against the atmosphere which was enough to push it under by the squeeze down effect I mentioned earlier.

I noticed as the rock was sitting at the bottom of the tank, it was giving off the odd rising bubble.
Guess what this was?

This was the pressure of the water squeezing the rock and forcing out trapped atmosphere.
Imagine if the tank was much deeper?

You see, what we're really dealing with, in reality, is, denpressure, which is the displacement of atmospheric pressure by any dense mass.
The reason why this happens is the reason we can actually measure it on a man made scale  and convert it to a weight measurement for us to understand.

Now the only way to measure the density of an object is by all of that dense mass pushing against the atmosphere and resisting the push back of that atmosphere back onto it's own mass by resisting against it by using a solid foundation.
That could be the solid ground or a solid plate on that solid ground that could be compressed down to read a measurement.

You could say that the entire volume of the object is displacing the atmosphere but it's not quite true.
Why?
Because the atmosphere will also be a part of that volume which basically negates the push against it by creating a neutral force.

Now imagine putting a dense object on a floating scale plate on the water?
What would happen?
It's clear that the dense object will do exactly what I explained above but there's a problem.
The scale plate doesn't have a solid foundation to resist the atmospheric push back onto the dense objects resistance of it, so it sinks. It's pushed under the water and so cannot give a true reading.

Video please.

Scepti, I would bet everything I own that the larger hollow plastic cube would displace more water than the smaller rock. Are you that confident in denpressure?

Quote from: sceptimatic on January 25, 2017, 11:41:23 PM

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

Assuming that the cube sinks, then the boat would displace more water than the cube.

As a boat, the metal displaces an amount of water equal to its own weight. As a cube that has sunk it displaces an amount of water equal to its volume. Since the density of the metal is greater than that of water (known because the cube sinks), then the first amount is greater than the second.

That's all I was trying to say but it gets twisted by mainstream science indoctrinates.

Quote from: sceptimatic on January 25, 2017, 11:41:23 PM

So here's a question.

If you had a cube of metal and dropped it into the water, it would displace a certain amount of water.
The same cube flattened out and made into a open container, like a boat will float on the top of the water.

Question:
Which one displaces more water?
Or
Do they both displace the same amount of water, roughly?

Answer: The boat.

If you take a cube of metal 10cm x 10cm x 10cm, or 1000cm^3.
Then drop it in to water it will displace 1000cm^3 or 1 litre. This will weigh very nearly 1 kilogram.

Now if you fashion the entire metal cube into a boat form and place it in the water it will displace a different volume, and subsequently a different weight of water depending on the metal.
Magnesium will displace about 1.74l
Steel about 7.5l
Copper about 8.93l
Lead about 11.34
Gold about 19.32l
Tungsten about 19.60l

Now think about what you've just put.

Maybe the occupants of a submarine want to know how much breathable air they have when they're underwater.

Yeah, maybe, eh? 

If the object is just floating, then it displaces its weight of water.  If the object is completely submerged, then it displaces its volume of water.

I really don't understand why that's so confusing.

But it's not all floating. Some of it is submerged, so what is acting on it to slightly sink it?

  Floating and submerged are two different conditions and therefore different amounts of water are displaced for different reasons.

What different reasons are these?

Scepti, I would bet everything I own that the larger hollow plastic cube would displace more water than the smaller rock. Are you that confident in denpressure?

I can't see your larger hollow plastic tube and I can't see your smaller rock, (I said rock, you perv's) so what kind of sneaky bullshit is this you're trying to pull?

Quote from: markjo on January 26, 2017, 05:33:45 AM

If the object is just floating, then it displaces its weight of water.  If the object is completely submerged, then it displaces its volume of water.

I really don't understand why that's so confusing.

But it's not all floating. Some of it is submerged, so what is acting on it to slightly sink it?

Gravity.

Quote from: markjo on January 26, 2017, 05:33:45 AM

  Floating and submerged are two different conditions and therefore different amounts of water are displaced for different reasons.

What different reasons are these?

If the overall density of the object is less than the density of the water, the object will float.
If the overall density of the object is greater than the density of the water, the object will sink.

I guess Scetpti never played with toys in the bathtub as a kid and figured that out lol.

I guess Scetpti never played with toys in the bathtub as a kid and figured that out lol.

It's completely irrelevant to the discussion, but it took my eye:
"Those people who think they know everything are a great annoyance to those of us who do."
Or is it irrelevant, with  Sceppy involved  ?

By the way, I believe it's "Sceppy" outside this site, see I was almost getting pulled into Sceppy’s “gravity is denpressure” …
Mind you, I would not go to Wild Heretic for much factual information either, but it's interesting to see what goes on in the big bad world out there.
And more in CluesForum, What is Gravity?
with direct like to What is Gravity? Post by sceppy on May 26th, 2015, 5:13 pm

I just thought people should give due credit to our celebrity and show

Quote from: sceptimatic on January 26, 2017, 08:54:49 AM

Quote from: markjo on January 26, 2017, 05:33:45 AM

If the object is just floating, then it displaces its weight of water.  If the object is completely submerged, then it displaces its volume of water.

I really don't understand why that's so confusing.

But it's not all floating. Some of it is submerged, so what is acting on it to slightly sink it?

Gravity.

Explain how gravity works in the water.

Quote from: markjo on January 26, 2017, 05:33:45 AM

  Floating and submerged are two different conditions and therefore different amounts of water are displaced for different reasons.

What different reasons are these?

Quote

If the overall density of the object is less than the density of the water, the object will float.
If the overall density of the object is greater than the density of the water, the object will sink.

Of course, because it's all down to the density of the object, which I keep telling you people.
Mainstream scientists are playing a little sleight of hand to favour a fictional gravity because failure for them to do so would render gravity the fiction I know it is and would bring in the real reason for why everything happens on this flattish Earth.
Denpressure.

I guess Scetpti never played with toys in the bathtub as a kid and figured that out lol.

Yeah, that about solves it. 

Gravity works the same in water as in air. The force downwards is the same.

Density is involved but only because it describes the amount of mass in a given volume. An object dropped into water will displace more and more water as it sinks until it is completely submerged and then will displace its own volume.

If at any point the amount of mass of water displaced equals the mass of the object then it will float. Density (or apparent density for porous or shaped objects) is an easy way to determine how buoyant and object might be. Less dense than water and it will float as it displaces more than its own mass of water. More dense and it will sink as it displaces less than its mass of water.

Imagine you remove gravity from the equation.
How water would act?

Check here: https://www.instagram.com/p/BA28oQMNPqR/

Gravity works the same in water as in air. The force downwards is the same.

Ok, fair enough. How about explaining how it works. Don't just say it does because that's not an answer and neither is mass attracting mass.
You people whine on and moan about me not telling you how mine works when I clearly explain it and yet you people never explain what gravity is in terms of how mass on mass does what it does, in realistic terms that can be proven.

Density is involved but only because it describes the amount of mass in a given volume. An object dropped into water will displace more and more water as it sinks until it is completely submerged and then will displace its own volume.
 

It cannot displace it's full volume until it sinks properly. Only density of an object can sink that object. trapped atmospheric pressure within that object will create a buoyancy if the object does not fully sink to depth.
This is why the volume shenanigans is flawed, because the volume can be used in two ways.
The volume of a bar of gold or the volume of a wooden block.

The issue is, the volume of a bar of gold will displace it's own density of water almost immediately where as the wooden block (assuming being able to submerge) will not immediately displace all of the water for it's own density and will only do so when it's crushed down to a depth where it releases almost all of it's air, which then makes the block more compressed and SMALLER, which is key to understanding what's really happening, because this then displaces a little less water.

The only way to displace more water by using the volume dupe that gets used is to add energy to the volume to sink it in order to displace that water....or, add DENSITY to the volume of air inside the object.

It's a clever dupe but a dupe nonetheless.

If at any point the amount of mass of water displaced equals the mass of the object then it will float. Density (or apparent density for porous or shaped objects) is an easy way to determine how buoyant and object might be. Less dense than water and it will float as it displaces more than its own mass of water. More dense and it will sink as it displaces less than its mass of water.

The real displacement of water comes from an object that stays above the water, because you negate the atmosphere trapped within it because it becomes part of the actual atmospheric pressure that is causing the push in the first place to displace that water. Not gravity bullshit.

Add dense mass to that and you cause the boat (for instance) to be pushed down further against the water crushing back, because that dense object added to the boat has taken up the amount of atmospheric pressure that was in that space but is now added to the atmospheric crush back onto the object and is transferred to the resistance of the boat against the water resistance to that.

Read it carefully, it does make sense if you dare to allow it.

Imagine you remove gravity from the equation.
How water would act?

Check here: https://www.instagram.com/p/BA28oQMNPqR/

This nonsense doesn't help because there's no such thing as zero gravity and no such thing as a bouncing water bubble.
Come on, seriously, if you're interested in finding a truth, don't use this crap as some kind of proof.

Quote from: Mainframes on January 27, 2017, 12:44:40 AM

Gravity works the same in water as in air. The force downwards is the same.

Ok, fair enough. How about explaining how it works. Don't just say it does because that's not an answer and neither is mass attracting mass.
You people whine on and moan about me not telling you how mine works when I clearly explain it and yet you people never explain what gravity is in terms of how mass on mass does what it does, in realistic terms that can be proven.

Quote from: Mainframes on January 27, 2017, 12:44:40 AM

Density is involved but only because it describes the amount of mass in a given volume. An object dropped into water will displace more and more water as it sinks until it is completely submerged and then will displace its own volume.
 

It cannot displace it's full volume until it sinks properly. Only density of an object can sink that object. trapped atmospheric pressure within that object will create a buoyancy if the object does not fully sink to depth.
This is why the volume shenanigans is flawed, because the volume can be used in two ways.
The volume of a bar of gold or the volume of a wooden block.

The issue is, the volume of a bar of gold will displace it's own density of water almost immediately where as the wooden block (assuming being able to submerge) will not immediately displace all of the water for it's own density and will only do so when it's crushed down to a depth where it releases almost all of it's air, which then makes the block more compressed and SMALLER, which is key to understanding what's really happening, because this then displaces a little less water.

The only way to displace more water by using the volume dupe that gets used is to add energy to the volume to sink it in order to displace that water....or, add DENSITY to the volume of air inside the object.

It's a clever dupe but a dupe nonetheless.

Quote from: Mainframes on January 27, 2017, 12:44:40 AM

If at any point the amount of mass of water displaced equals the mass of the object then it will float. Density (or apparent density for porous or shaped objects) is an easy way to determine how buoyant and object might be. Less dense than water and it will float as it displaces more than its own mass of water. More dense and it will sink as it displaces less than its mass of water.

The real displacement of water comes from an object that stays above the water, because you negate the atmosphere trapped within it because it becomes part of the actual atmospheric pressure that is causing the push in the first place to displace that water. Not gravity bullshit.

Add dense mass to that and you cause the boat (for instance) to be pushed down further against the water crushing back, because that dense object added to the boat has taken up the amount of atmospheric pressure that was in that space but is now added to the atmospheric crush back onto the object and is transferred to the resistance of the boat against the water resistance to that.

Read it carefully, it does make sense if you dare to allow it.

Porous object always add a level of complexity to buoyancy. Yes an object like a closed foam block will displace more water than just the physical volume of the foam because it has a lot of trapped air, wood is an example. This is very specific to porous objects. Blocks of metal ARE NOT POROUS and if more dense than water will displace exactly their volume.

Boat hulls are a different class of object all together as the shape of the hull is designed to displace huge amounts of water whilst having very little mass. Using your example; how do you explain why adding mass to the boat will displace EXACTLY that mass of water. Your denpressure simply cannot explain this.

And for the final time. Gravity is the attraction between objects of mass. The exact cause is unknown, be it curved space time or gravitons but the results are unanimous, well-explained, measured and predictible.

Porous object always add a level of complexity to buoyancy.

There's no complexity. It's straightforward. It's just made to look complex because it's a mix of truth and fantasy gravity bullshit to explain that truth when it's clear what the real cause and effect is. Denpressure.

Yes an object like a closed foam block will displace more water than just the physical volume of the foam because it has a lot of trapped air, wood is an example. This is very specific to porous objects.

All objects are porous but the most dense ones are so dense as to have virtually so little pores that they are probably not recognised on ordinary microscopes.

Blocks of metal ARE NOT POROUS and if more dense than water will displace exactly their volume.

Yes they are porous.
Put an ice cube in a drinking glass and fill the glass to the top. Allow the ice cube to melt and you'll see that the glass does not overflow.
Why?

Boat hulls are a different class of object all together as the shape of the hull is designed to displace huge amounts of water whilst having very little mass. Using your example; how do you explain why adding mass to the boat will displace EXACTLY that mass of water. Your denpressure simply cannot explain this.

My denpressure explains it perfectly but you go for gravity which cannot be explained.
I've just explained to you why the mass in the boat displaces the water of it's own density.
The dense mass displaces the atmosphere it is in by compressing it away from itself by that density of the object.
That pressure is placed right back onto the object which it resists against and so pushes down the boat.

The other way to measure it is by a scale plate on solid ground with the scale plate being the boat and the mechanism below the scale plate being the water with an object placed upon that scale plate, that object displaces the atmosphere like I said and now you have a man made measured reading of weight.

It would match the amount of water displaced by the exact same object.
No gravity nonsense, just good old atmospheric pressure upon any dense material.

And for the final time. Gravity is the attraction between objects of mass. The exact cause is unknown, be it curved space time or gravitons but the results are unanimous, well-explained, measured and predictible.

Unknown but easily explainable?
Ok let's  see.
Let's start with curved space time.
Tell me briefly how and why curved space time works.

Then, if you don't mind, tell me about gravitons. What are they are where do you find them and how do they act?

I'd like to see better answers than this....And for the final time. Gravity is the attraction between objects of mass.

The issue is, the volume of a bar of gold will displace it's own density of water...

No. No. No.

You can displace volume and you can displace mass, but you can not displace density.  Mass and volume are physical units of measure.  Density is the ratio between those two units of measure. 

You can go to a store and buy soda by liter and you can buy meat by the kilogram, but you can't buy 1 kg/l of anything because density is not a physical unity of measure.

In the same way, you can displace 1 liter of water and you can displace 1 kilogram of water, but you cannot displace 1 kg/l of water.

Quote from: sceptimatic on January 27, 2017, 02:26:41 AM

The issue is, the volume of a bar of gold will displace it's own density of water...

No. No. No.

You can displace volume and you can displace mass, but you can not displace density.  Mass and volume are physical units of measure.  Density is the ratio between those two units of measure. 

You can go to a store and buy soda by liter and you can buy meat by the kilogram, but you can't buy 1 kg/l of anything because density is not a physical unity of measure.

In the same way, you can displace 1 liter of water and you can displace 1 kilogram of water, but you cannot displace 1 kg/l of water.

The density of a volume of mass is how much that volume of mass can be condensed. That's basically the density.

It's this that is the crux of the matter because it is this which is the true meaning of displacement by density.

So it doesn't matter how much you want to play with what you believe are measurements, the true measurement is the atmospheric pressure upon the density of a mass and volume.

Volume does not displace water. It's the density of the mass as part of that volume that displaces it.

Quote from: Mainframes on January 27, 2017, 05:04:43 AM

Blocks of metal ARE NOT POROUS and if more dense than water will displace exactly their volume.

Yes they are porous.
Put an ice cube in a drinking glass and fill the glass to the top. Allow the ice cube to melt and you'll see that the glass does not overflow.
Why?

An ice cube floats as it is less dense than water.
The mass of water displaced by the ice cube is exactly the same as the mass of the ice cube as it is floating.
When the cube melts its volume will decrease as water is more dense and will take up an identical volume of water that it had displaced due the mass being equal.

You can even calculate it quite easily:

water = 1g / cm³
ice = 0.92g / cm³

Take a 500ml beaker with an ice cube of 10cm³ and fill to the top with water. Total volume 500ml or 500cm³.

Volume of ice = 10cm³ therefore mass of ice 10 x 0.92 = 9.2g

Ice floats therefore mass of water displaced = 9.2g

Volume of water displaced = 9.2g / 1g/cm³ = 9.2cm³

Volume of water in beaker  = 500 - 9.2 = 490.8cm³

Mass of water = 490.8 * 1 = 490.8g

Mass of water + Ice = 490.8 + 9.2 = 500g

Ice melts into water.

Mass of water is still 500g but now has a volume of 500g / 1 g/cm³ = 500cm³

Exactly filling the beaker.

Quote from: markjo on January 27, 2017, 06:28:20 AM

Quote from: sceptimatic on January 27, 2017, 02:26:41 AM

The issue is, the volume of a bar of gold will displace it's own density of water...

No. No. No.

You can displace volume and you can displace mass, but you can not displace density.  Mass and volume are physical units of measure.  Density is the ratio between those two units of measure. 

You can go to a store and buy soda by liter and you can buy meat by the kilogram, but you can't buy 1 kg/l of anything because density is not a physical unity of measure.

In the same way, you can displace 1 liter of water and you can displace 1 kilogram of water, but you cannot displace 1 kg/l of water.

The density of a volume of mass is how much that volume of mass can be condensed. That's basically the density.

It's this that is the crux of the matter because it is this which is the true meaning of displacement by density.

So it doesn't matter how much you want to play with what you believe are measurements, the true measurement is the atmospheric pressure upon the density of a mass and volume.

Volume does not displace water. It's the density of the mass as part of that volume that displaces it.

No.

Density is mass per unit volume. Stop confusing porosity and voidage with density.

Volume displaces volume. This is repeatable in every test ever made.

Quote from: markjo on January 27, 2017, 06:28:20 AM

Quote from: sceptimatic on January 27, 2017, 02:26:41 AM

The issue is, the volume of a bar of gold will displace it's own density of water...

No. No. No.

You can displace volume and you can displace mass, but you can not displace density.  Mass and volume are physical units of measure.  Density is the ratio between those two units of measure. 

You can go to a store and buy soda by liter and you can buy meat by the kilogram, but you can't buy 1 kg/l of anything because density is not a physical unity of measure.

In the same way, you can displace 1 liter of water and you can displace 1 kilogram of water, but you cannot displace 1 kg/l of water.

The density of a volume of mass is how much that volume of mass can be condensed. That's basically the density.

It's this that is the crux of the matter because it is this which is the true meaning of displacement by density.

So it doesn't matter how much you want to play with what you believe are measurements, the true measurement is the atmospheric pressure upon the density of a mass and volume.

Volume does not displace water. It's the density of the mass as part of that volume that displaces it.

As said before you cannot change the definition of density.

Some typical numbers for the bold above please.

The density of a volume of mass is how much that volume of mass can be condensed. That's basically the density.

No, that's basically gibberish.

Volume does not displace water. It's the density of the mass as part of that volume that displaces it.

More gibber jabber.