Re: [Phys-L] science versum math WAS: Buoyancy Questions

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

This leads to the question: Is math invented or discovered?

Phys-L@Phys-L.org writes:
> P.S.
> Mathematicians, on the other hand, do not perform experiments; their
> statements are validated logically, using accepted axioms and
> already-proven theorems. This is also worth emphasizing. Yes, we all use
> logic. That is why some people think that mathematics is science.
>
> Was the Pythagorean relation first discovered (by experimenting with
> triangles) or was it first derived? I strongly suspect that it was first
> discovered and then formally validated.  
>
> ====================================================
>
>
> Speculations not based on experimental data
>
> On Jul 2, 2013, at 3:11 PM, Ludwik Kowalski wrote:
>
> > Does a wooden ball, of the same size as the mostly-air ball, exhibit
> the same behavior? If not then the role of gravity is important (the
> buoyant force being nearly the same). That seems to be an experiment
> worth performing. 
> > Another parameter worth changing is the size of the mostly-air ball. Do
> balls of different size behave in the same way? Experiments designed to
> answer such questions, first qualitatively and then quantitatively, are
> worth performing. They offer a chance to do what scientist do, when they
> try to understood what happens.
> > Ludwik Kowalski
> > http://csam.montclair.edu/~kowalski/life/intro.html 
> >
> > =============================================
> >
> > On Jul 2, 2013, at 2:49 PM, John Clement wrote:
> > > It has to be something unique to having been far underwater.  So a
> > > reasonable hypothesis is that there is still water on the upper side
> as it
> > > comes out, which adds to the weight and makes decreases the net force
> on the
> > > ball as it comes out.  This might be testable if you take a video of
> it.
> > > You may see that as the ball emerges there is still a significant
> layer of
> > > water on top of it when you push it far underwater.  The surface
> tension has
> > > nothing to do with it because it is underwater in both cases.  While
> fluid
> > > friction comes into play, near the surface this effect should be same
> no
> > > matter how deep you push it initially.
> > >
> > > So take the video and see what is happening!
> > >
> > > John M. Clement
> > > Houston, TX
> > >
> > >
> > >
> > > > > I was at my sister's pool a few days ago and I noticed that when I 
> > > > > took a ball (a pool volleyball) and submersed it just below the 
> > > > > surface and released it, the ball would jump around 3 or 4 
> > > > feel above 
> > > > > the surface of the water.  When I pushed the ball deeper, 
> > > > about 2 or 3 
> > > > > feet below the surface and let go, the ball would rise and 
> > > > then sort 
> > > > > of sputter at the surface and not rise above the surface at 
> > > > all.  Does 
> > > > > anyone know how to explain this.  I thought it would be a nice 
> > > > > challenge for my students but the problem is, I don't think 
> > > > I know what's going on either.
> > > > > Thanks in advance.
> > > > > Mike Barr
> > > > >
> > > > >
> > > > > --
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