[ExI] scieceblind

Dylan Distasio interzone at gmail.com
Fri Oct 13 17:56:56 UTC 2017


Bill-

I will leave it to my betters on this list like John C. in terms of
corrections to my explanation, but as far as I know it is more about
buoyancy, displacement, and Archimedes' principle regarding the WEIGHT of
an object.  Gravity is constant across both the air and the balloon but
because of the density/displacement the weight of the balloon is less than
the air around it, so it floats.

An object that sinks displaces an amount of fluid equal to the object's
volume. Thus buoyancy <https://en.wikipedia.org/wiki/Buoyancy> is expressed
through Archimedes' principle
<https://en.wikipedia.org/wiki/Archimedes%27_principle>, which states that
the weight <https://en.wikipedia.org/wiki/Weight> of the object is reduced
by its volume multiplied by the density
<https://en.wikipedia.org/wiki/Density> of the fluid. If the weight of the
object is less than this displaced quantity, the object floats; if more, it
sinks. The amount of fluid displaced is directly related (via Archimedes'
Principle) to its volume.

The link has a full explanation of the principle.

Hopefully, I'm accurate here.  College physics is a long ways from these
parts for me.



On Fri, Oct 13, 2017 at 1:20 PM, William Flynn Wallace <foozler83 at gmail.com>
wrote:

> No one of any age should be insulted when someone tries to cure their
> ignorance.  I don't mind being ignorant.  It's not shameful to me.  I just
> enjoy not being ignorant any more, so I am thankful to all who help me.
>
> Thanks to you and to John Clark for the table explanation.
>
> I still don't get some of it.  Say you take a less dense object and put it
> underwater.  Since it is less dense, does that mean that gravity pulls less
> on it?  And why should the water exert less of an upward force than on
> something more dense?  Or is it gravity?
>
> If I were standing in a vacuum, would there be less holding me up since
> there is no air to exert an upward force on my body?  If this is correct, I
> am beginning to get it, eh?
>
> bill w
>
> On Fri, Oct 13, 2017 at 11:40 AM, Mike Dougherty <msd001 at gmail.com> wrote:
>
>> On Fri, Oct 13, 2017 at 12:07 PM, Dylan Distasio <interzone at gmail.com>
>> wrote:
>>
>>> I hope I'm not insulting by linking to an explanation, but I think it
>>> would help if you think about water displacement and how a less dense
>>> object floats in water.  It is the same exact principle when you have a
>>> less dense object (the helium balloon) compared to the air:
>>>
>>> http://science.howstuffworks.com/helium1.htm
>>>
>>>
>> Have we figured out how to fill a balloon with near-enough to nothing at
>> all to make a lighter than helium balloon?
>>
>> I know the structural requirement for a large volume of empty space is
>> considerable in Earth atmosphere.  I've been curious about the use of
>> aerogels with enough crush-resistance to make lighter-than air craft
>> literally filled with nothing - which would be cheaper and much safer than
>> the only [non-]thing with more lifting power than helium (see:
>> Hindenberg).  I mean sure, worse case scenario your balloon fills with
>> environmental air and crashes to the ground wouldn't exactly be a good time
>> but at least you wouldn't also be exploding and burning on the way to the
>> impact.
>>
>> I was also wondering if you could tether enough of these together to
>> encircle the globe, if you could hoist objects from this floating platform
>> and literally throw them into space.  Imagine a trebuchet floating on a
>> ship launching rocks lifted from the ocean floor, but the ship is floating
>> on the atmosphere and the rocks are aerodynamic sling bullets heading to
>> space.
>>
>> Well, enough thought experiment for now, I have to do actual work.
>>
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>
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