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Re: Why does a less dense object rise in a dense fluid surrounding?

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On 10/01/2019 4:12 pm, Arindam Banerjee wrote:
> On Earth. Why does a less dense object rise up in a dense fluid surrounding medium?
> So exactly why does a cork bounce up when submerged in water?

The force on a part of an object object due to the water is always 
perpendicular to the surface of the object. Perform the vector sum of 
all those forces.

Now consider that the object was replaced by the same volume of water, 
with the same shape. It would have exactly the same forces acting on it 
due to the surrounding water.

Since that water would stay where it is, the vector sum of all the 
forces from the water surrounding it must be equal and opposite to its 
weight, which is to say, the force is upwards.

Nor put back the original object. The vector sum of all the forces 
acting on it still equals the weight of the water that would otherwise 
be there. But since the object is less dense than water, that force is 
greater than its weight. There is therefore an upwards force on the 
object that is greater than its weight, so it will accelerate upwards.

 > If the top of a hot air balloon was pointy instead of flat would it rise?
 >
Yes, the shape has nothing to do with it.

Now try figuring out where the forces act on a piece of cooked spaghetti 
when you suck it into your mouth.

Sylvia.

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Why does a less dense object rise in a dense fluid surrounding? Arindam Banerjee <banerjeeadda1234@gmail.com> - 2019-01-09 21:12 -0800
  Re: Why does a less dense object rise in a dense fluid surrounding? Sylvia Else <sylvia@email.invalid> - 2019-01-10 23:20 +1100
    Re: Why does a less dense object rise in a dense fluid surrounding? Arindam Banerjee <banerjeeadda1234@gmail.com> - 2019-01-10 05:10 -0800
      Re: Why does a less dense object rise in a dense fluid surrounding? Odd Bodkin <bodkinodd@gmail.com> - 2019-01-10 13:32 +0000
        Re: Why does a less dense object rise in a dense fluid surrounding? benj <benj.fake@gmail.com> - 2019-01-10 13:13 -0500
      Re: Why does a less dense object rise in a dense fluid surrounding? Sylvia Else <sylvia@email.invalid> - 2019-01-13 16:31 +1100
    Re: Why does a less dense object rise in a dense fluid surrounding? poraty6@gmail.com - 2019-01-10 16:11 -0800
  Re: Why does a less dense object rise in a dense fluid surrounding? Odd Bodkin <bodkinodd@gmail.com> - 2019-01-10 13:00 +0000
    Re: Why does a less dense object rise in a dense fluid surrounding? Arindam Banerjee <banerjeeadda1234@gmail.com> - 2019-01-10 05:04 -0800
      Re: Why does a less dense object rise in a dense fluid surrounding? benj <benj.fake@gmail.com> - 2019-01-10 13:12 -0500
    Re: Why does a less dense object rise in a dense fluid surrounding? benj <benj.fake@gmail.com> - 2019-01-10 13:11 -0500
      Re: Why does a less dense object rise in a dense fluid surrounding? Odd Bodkin <bodkinodd@gmail.com> - 2019-01-10 19:14 +0000
        Re: Why does a less dense object rise in a dense fluid surrounding? "reber G=emc^2" <herbertglazier0@gmail.com> - 2019-01-10 12:28 -0800
          Re: Why does a less dense object rise in a dense fluid surrounding? benj <benj.fake@gmail.com> - 2019-01-10 19:36 -0500
            Re: Why does a less dense object rise in a dense fluid surrounding? "reber G=emc^2" <herbertglazier0@gmail.com> - 2019-01-11 09:40 -0800
        Re: Why does a less dense object rise in a dense fluid surrounding? mitchrae3323@gmail.com - 2019-01-10 13:21 -0800
        Re: Why does a less dense object rise in a dense fluid surrounding? benj <benj.fake@gmail.com> - 2019-01-10 19:32 -0500
          Re: Why does a less dense object rise in a dense fluid surrounding? Odd Bodkin <bodkinodd@gmail.com> - 2019-01-11 16:20 +0000
            Re: Why does a less dense object rise in a dense fluid surrounding? poraty6@gmail.com - 2019-01-12 23:56 -0800
              Re: Why does a less dense object rise in a dense fluid surrounding? Odd Bodkin <bodkinodd@gmail.com> - 2019-01-13 12:40 +0000
                Re: Why does a less dense object rise in a dense fluid surrounding? poraty6@gmail.com - 2019-01-13 16:01 -0800
    Re: Why does a less dense object rise in a dense fluid surrounding? poraty6@gmail.com - 2019-01-10 16:13 -0800
  Re: Why does a less dense object rise in a dense fluid surrounding? mitchrae3323@gmail.com - 2019-01-10 10:46 -0800
    Re: Why does a less dense object rise in a dense fluid surrounding? Sergio <invalid@invalid.com> - 2019-01-13 15:40 -0600

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