<div dir="ltr">Bill-<div><br></div><div>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.</div><div><br></div><div><span style="font-family:sans-serif;font-size:14px">An object that sinks displaces an amount of fluid equal to the object's volume. Thus </span><a href="https://en.wikipedia.org/wiki/Buoyancy" title="Buoyancy" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">buoyancy</a><span style="font-family:sans-serif;font-size:14px"> is expressed through </span><a href="https://en.wikipedia.org/wiki/Archimedes%27_principle" title="Archimedes' principle" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">Archimedes' principle</a><span style="font-family:sans-serif;font-size:14px">, which states that the </span><a href="https://en.wikipedia.org/wiki/Weight" title="Weight" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">weight</a><span style="font-family:sans-serif;font-size:14px"> of the object is reduced by its volume multiplied by the </span><a href="https://en.wikipedia.org/wiki/Density" title="Density" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">density</a><span style="font-family:sans-serif;font-size:14px"> 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.</span><br></div><div><span style="font-family:sans-serif;font-size:14px"><br></span></div><div><span style="font-family:sans-serif;font-size:14px">The link has a full explanation of the principle.</span></div><div><span style="font-family:sans-serif;font-size:14px"><br></span></div><div><span style="font-family:sans-serif;font-size:14px">Hopefully, I'm accurate here. College physics is a long ways from these parts for me.</span></div><div><span style="font-family:sans-serif;font-size:14px"><br></span></div><div><span style="font-family:sans-serif;font-size:14px"><br></span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Oct 13, 2017 at 1:20 PM, William Flynn Wallace <span dir="ltr"><<a href="mailto:foozler83@gmail.com" target="_blank">foozler83@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000">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.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000">Thanks to you and to John Clark for the table explanation. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000">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?</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000">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?</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#000000">bill w</div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Fri, Oct 13, 2017 at 11:40 AM, Mike Dougherty <span dir="ltr"><<a href="mailto:msd001@gmail.com" target="_blank">msd001@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span>On Fri, Oct 13, 2017 at 12:07 PM, Dylan Distasio <span dir="ltr"><<a href="mailto:interzone@gmail.com" target="_blank">interzone@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">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:<div><br></div><div><a href="http://science.howstuffworks.com/helium1.htm" target="_blank">http://science.howstuffworks.c<wbr>om/helium1.htm</a><br></div></div><div class="m_1094449354805042400m_2214061799709644354HOEnZb"><div class="m_1094449354805042400m_2214061799709644354h5"><div class="gmail_extra"><div class="gmail_quote"><br></div></div></div></div></blockquote><div><br></div></span><div>Have we figured out how to fill a balloon with near-enough to nothing at all to make a lighter than helium balloon?</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div><br></div><div>Well, enough thought experiment for now, I have to do actual work.</div></div></div></div>
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