Re: No free lunch

Spaceman wrote:
nospamplease wrote:
Spaceman wrote:
nospamplease wrote:
Spaceman wrote:
nospamplease wrote:
Ask any high school
graduate, in order for your 45kg mass to float, it
must displace 45kg of water.
Ask them also why you are wrong.
Do you think that the entire mass is displaced when
it "floats"

Yes. 100% of the time, 100% of the mass of an
object must be displaced for it to float. If that
requires less than 100% of the volume of the
object, then it floats, otherwise it sinks
(density at play here).
Try a simple experiment for yourself.
A cubic foot that floats half way
only displaces 1/2 a cubic foot of water.
and the water will rise 1/2 a cubic foot ,
(the displacement) in the container.

Agreed. But did you also know that your object
must have a mass of ~14kg and a density of 0.5.


No 100% water displacement is occuring
only 50% in such.
Dude, make up your mind, are you talking about
mass or volume? The laws of physics require that
100% of the mass is being displaced. The
percentage volume of the object being displaced is
dependent on its density. You've indirectly said
its density is 0.50 by saying it was displacing
half its volume.

Dude,
the mass makes up the volume.
50 % of the mass is 50% of the volume.


If I make it sink, 100% of the cubic foot
will make the water rise 100% of the cubic foot.
You really should try to check this out
in an actual experiment.
I have.
in gradeschool.
I don't need to try that experimentally. I already
know it's true. You know the difference between
mass & volume right?

Yes,
I also know that percentage wise they equal.
50% of the mass = 50% of the volume in a cube
like I used.

Try to cut a cube in half and tell me that you
do not have 50% volume in each piece
and then tell me that you do not have 50% mass.
C,mon man.
Don't think like a textbook,
think like you are thinking for your own self
instead.

It was a cube.
I could see if I said boat,
that would make a big difference,
but I said cube.



I think you're still having a problem with the concept of mass. An important concept if you're trying to build stuff like cars, airplanes, spaceship. Here on earth, the amount of air an object displaces also affects an objects weight. There's a good reason a lot of stuff is sold by mass (kg) not weight (lbs). The gravitational force (lbs or Newtons) between objects varies inversely as the square of their distance. But their mass (Kg, Stone, Slug) doesn't change. When your 100lb cube is floating, by definition it is weightless (0 lbs). Half its volume is submerged, all of its mass is being displaced (45kg or 45 Liters of water). Also true that all of it's weight is being displaced (if you measure its weight near the water). Flotation isn't the best way to demonstrate the concept of mass. But the energy of an object in motion is a function of its mass, not its weight or volume. If you don't think this is an important distinction, try making your millions selling helium balloons by the pound.
.

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