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How "gravity" is actually the relationship between buoyancy and density

"...Say, 'GOD is sufficient for me.' In Him the trusters shall trust." (Quran 39:38)


  • Rosie_MOD_Rosie_MOD_ Moderator
    edited February 2017
    So 500  air or helium filled balloons would float but 500 empty (flat) balloons packed all together or even one, would have density (weight) and thus attract gravity?  i.e. In water we float because our lungs are capable of holding air otherwise gravity would pull us down in the water (drowning) We still weigh the same with or without our lungs expanded with air.  

    "We are shaped by our thoughts; we become what we think. When the mind is pure, joy follows like a shadow that never leaves."

  • Matt_ADMIN_Matt_ADMIN_ Administrator
    That's right: a balloon filled with helium has less density than the air around it, so it rises. A balloon filled with regular air has a greater density than the air around it (because of the balloon itself) and so falls. As the video shows, this can be balanced almost perfectly to match the density of the surrounding air, so that the balloon neither rises nor falls.

    It works the same way for a human being. Depending on a person's density, they will either rise or fall in the water. A person's density will fluctuate according to the amount of air / gas they contain, and if they possess enough, a human being will be less dense than the medium they're in (such as water), and will therefore float.

    The point is this: gravity and weight don't actually exist. "Gravity" is just a complicated mathematical expression of density and buoyancy (density is down, buoyancy is up). "Weight" is just a measurement of density within a particular medium (for example, a balloon full of air, when placed in air, will "weigh" more (be more dense) than a balloon full of helium when placed in air).

    An easy way to imagine it is this: draw an imaginary circle around something, and then compare its density to what it's currently in an equation. Here are some examples:

    Balloon + atmosphere vs atmosphere = the left side being more dense

    Balloon + helium vs atmosphere = the right side being more dense

    Balloon + atmosphere vs water = the right side being more dense

    Notice how in the air, a balloon filled with regular air will sink, but that same balloon will rise when placed in the water? That's a demonstration of buoyancy and density. If "gravity" actually existed, their densities of the various materials would no longer matter.
    "...Say, 'GOD is sufficient for me.' In Him the trusters shall trust." (Quran 39:38)
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