Re: [Phys-L] Nice question on buoyancy and balance

[Philip Keller <pkeller@holmdelschools.org>]

But suppose the reason I put my hand in the water was to reach down and
grab a thread that was tied to the bottom of the tank so that I could pull
up on the thread!  I understand that the reaction to the buoyancy force on
my hand pushes down on the beaker.  But you can't ignore the tension in the
thread.


On Wed, Jan 29, 2014 at 9:01 AM, Anthony Lapinski
<Anthony_Lapinski@pds.org>wrote:

> Spheres have same volume, so same amount of water displaced.
>
> Imagine placing your finger in a beaker of water on a scale, but don't
> touch the bottom of the beaker.
> What will happen to the scale reading?
>
> Why?
>
>
>
> Phys-L@Phys-L.org writes:
> > And from this you conclude...?
> >
> >
> > On Wed, Jan 29, 2014 at 7:55 AM, Anthony Lapinski
> > <Anthony_Lapinski@pds.org>wrote:
> >
> > > Simplify with fluids. The weight of the water displaced depends
> > > on the volume of the submerged object.
> > >
> > >
> > > Phys-L@Phys-L.org writes:
> > > > My first thoughts are that the ping-pong side rises.  I look at the
> > forces
> > > > acting on the bottom of the pan.  Both sides have pressure from the
> > water
> > > > but since it's same area and depth, those terms are equal.  But on the
> > > > left, there is a rope pulling up on the pan.
> > > >
> > > > On the other hand, if the ping pong ball had been held in place from
> > above
> > > > by a rigid dowel, say, then I'd guess that the pans would still
> > balance.
> > > > But since this is a buoyancy puzzle, I am prepared to be wrong...
> > > >
> > > >
> > > > On Wed, Jan 29, 2014 at 4:36 AM, Savinainen Antti <
> > > > antti.savinainen@kuopio.fi> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > a former studen of mine send me a link to a nice question:
> > > > > <http://wealthmanagement.com/question/puzzler-odd-balance>.
> > > > >
> > > > > I usually ask a variation of this question in my class. It is, in my
> > > > > opinion, a good example of conceptual reasoning which goes well
> > beyond
> > > > rote
> > > > > memorization. Probably many of you have seen this question before
> > but I
> > > > > thought it might be worth sharing.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Antti
> > > > >
> > > > > --
> > >
> > > *************************************************************************
> > > > > Viesti on tarkastettu roskapostinsuodatus- ja
> > > > virustorjuntaohjelmistolla.
> > > > >
> > >
> > > *************************************************************************
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