Re: Chez Watt: There can be no Evolution by natural selection DJT

On Nov 1, 11:52 pm, Christopher Denney <christopher.den...@xxxxxxxxx>
wrote:
On Nov 1, 9:09 pm, Christopher Denney <christopher.den...@xxxxxxxxx>
wrote:





On Nov 1, 4:00 pm, Rusty Sites <SpameYou...@xxxxxxxxxx> wrote:

Christopher Denney wrote:
On Oct 29, 2:44 pm, Rusty Sites <SpameYou...@xxxxxxxxxx> wrote:
Christopher Denney wrote:
On Oct 28, 7:44 pm, Rusty Sites <SpameYou...@xxxxxxxxxx> wrote:
Christopher Denney wrote:

[snip]

The displacement of an object depends only on how much volume is
enclosed by it's surface.
If the object is floating, it depends only on the weight of the object.
If it is submerged, then the displacement only depends on its volume.

If an object floats in water it's because it's density is less than
that of the water it's floating in.
Your experiment is both changing the density of the object, and it's
total volume.
Yes, but the point was that adding air to the iceberg does not change
the amount of water is displaces.

Actually it does, the iceberg is bigger because of the trapped air,
than it would be if it had no trapped air.
The trapped air displaces ice that would otherwise occupy it's volume.
Thus the density of the iceberg is less than just ice. (i.e. it's
bigger for the same mass of ice)
Thus the amount of water, per unit mass, displaced is increased.
That means that for every unit of mass of ice, the iceberg with air
trapped will ride higher in the water than the same mass of ice with
no air trapped, because it is less dense.

A real good demonstration, imagine a solid lead ball, will is sink or
float in water?
Now form that solid ball into a sphere that is hollow, using the same
mass of lead.
Amazingly it floats, why? Because the mass of the water it displaces
is more than the mass of then lead(and air).
The system is less dense because it has air trapped inside, the hollow
sphere is bigger than the solid one.

An object that sinks displaces its volume in water. A floating object
displaces a volume of water which has the same weight. By increasing
the volume of the ball, the amount of water displaced increases with its
volume until it starts to float. At that point, it is displacing its
weight in water and any more volume increase will not increase the
amount of water displaced. The same volume will be under water. The
volume above the water increases. An iceberg floats without any air so
adding air will not increase the amount of displacement.

Actually no, the more air in it, the less water it displaces, and more
mass is lifted above the surface.

As an example, I am relatively neutrally buoyant (last I checked) so I
typically displace the same weight of water as I weigh.
Now if I put on a wet suit that weighs a few pounds I float very high
in the water, suddenly I am displacing considerably fewer pounds of
water than I weigh.
I go from being able to submerge and swim underwater with a little
effort, to being trapped on the surface. So while I add to my total
displacement by adding a layer of neoprene to the outside of my skin,
my effective displacement goes down due to me floating above my normal
level.
Does that make more sense?
Back to the iceberg with air in it, it would displace less volume of
water floating along than the total volume of water it would be if
melted.

So it must've been an illusion, the mass of the displaced water has to
have equaled the mass of me+wet suit, so my vantage point of being
inside the wet suit must have made me think I was floating higher in
the water than I was, considering the wet suit. Since there was
considerably more of me above the water than usual. You know, we
must've covered this in dive class, the instructor liked that sort of
thing, I must've forgotten. (it was the 70s after all)

You were floating higher...no doubt about it. You would have displaced
the weight of water that was equal to your weight *plus the weight of
the wetsuit. This is because the wetsuit added a layer of foam rubber
to your body that increased your volume without adding very much
weight. This means that by the time that you had displaced your total
*weight of water, there was still quite a bit of you still out of the
water. You actually displace more water with the wetsuit on [due to
the increase in weight], but your overall density has been reduced, so
you float higher.

.

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