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Thread: Father Son Debate

  1. #1 Father Son Debate 
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    My Father asked me this question recently and before I undertake my own experiment to find out the answer I thought I would see what the educated opinion is. The question is; 'If you have a cone shaped piece of ice and you place it in a tank of water which end of the cone will point towards the sky?We had differing opinions for different reasons.Please let me know what you think and why!


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  3. #2  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Most things in nature try to reach a state of minimal energy. In this case, that would be a state where the center of mass is as low as possible. Working that out on paper would be an interesting mathematical exercise.


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    Administrator KALSTER's Avatar
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    Yep. Find the volume of a cone with a hight of X. Then find out what the hight of a cone with half the volume would be.?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    Forum Senior pineapples's Avatar
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    As a (lay)man of science, but more a gambling man- I’d hazard a guess and say the base end of the cone would float on top because it would likely contain more trapped air than the tip end of the cone? I’m fairly 50/50 on this!
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    Forum Senior pineapples's Avatar
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    Quote Originally Posted by pineapples View Post
    As a (lay)man of science, but more a gambling man- I’d hazard a guess and say the base end of the cone would float on top because it would likely contain more trapped air than the tip end of the cone? I’m fairly 50/50 on this!
    Actually, I’m thinking it’ll simply float on its side for the same reasoning.
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    Genius Duck Moderator Dywyddyr's Avatar
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    Apart from MagiMaster's answer (it depends where the CofG is) I just want to point out, in the interests of being awkward, that it depends on the aspect ratio.
    A tall cone of small diameter will probably float on its side...

    http://www.ocf.berkeley.edu/~wwu/cgi...num=1043941918
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  8. #7  
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    Thank you everyone for your input. It's comforting to know that the answer isn't as straight forward as one might think. Does displacement factor in to any of this?
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    Forum Masters Degree DianeG's Avatar
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    Which way do ice bergs float? Although, that might not be a good test if its freshwater ice floating in salt water.

    http://www.navcen.uscg.gov/?pageName...apesOfIcebergs
    Last edited by DianeG; February 19th, 2014 at 05:23 PM.
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    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by DianeG View Post
    How do ice bergs float?
    By not sinking!
    Water expands as it freezes: that means that, for a given mass of water, the volume is greater. Which means that ice is less dense than water.
    It can't help but float.
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by DianeG View Post
    How do ice bergs float?
    By not sinking!
    Water expands as it freezes: that means that, for a given mass of water, the volume is greater. Which means that ice is less dense than water.
    It can't help but float.
    Sorry for the late editing in my post. I meant which way would they float. The pictures on the link seem to show that a cone shaped berg would float with the base of the cone up.
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  12. #11  
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    Apparently these icebergs are quite unstable and as they melt away under the water they are liable to flip.

    Twillingate
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    Say the cone is stood with the vertex on top. Then slice a plane through the cone parallel to the base and bisects the height. The bottom piece clearly has a greater volume than the top piece. Thus in order for the volumes to be equal, the plane must be lowered to decrease the volume of the bottom and increase the volume of the top until they are equal. Then the center of gravity is closer to the base than the vertex. This will be at lowest point only when the base is pointing downward so the vertex will point to the top.
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    Malignant Pimple shlunka's Avatar
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    In other words, if I drop an ice cream cone that is long and narrow into a puddle, said ice cream is ruined. Yet, if I drop a short and wide cone into the water, I may salvage lunch?
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  15. #14  
    Forum Masters Degree DianeG's Avatar
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    These aren't quite conical.
    SHARK FIN ICE CUBE TRAY

    I was surprised that you can get ice cubes in so many shapes.
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  16. #15  
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    Quote Originally Posted by MagiMaster View Post
    Working that out on paper would be an interesting mathematical exercise.
    Working that out on paper would be pain in the ass.
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  17. #16  
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    It is a naval engineering problem concerning the stability of a V shaped hull.

    (even though it is a special case it is not that hard so long as you remember 10% of the ice is above the waterline and the stability depends on how far the center of bouyancy moves sideways when the iceberg heels. (due to the changing shape of the submerged portion and the changing shape of the above waterline portion)

    The only missing information is the aspect ratio of the cone, because as it become flatter it starts to resemble a saucer hull instead of a V-hull while a very deep cone starts to resemble a spar buoy.
    So you might have to solve for a flat cone, a medium cone, and a deep cone.
    Last edited by dan hunter; February 20th, 2014 at 06:09 PM.
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  18. #17  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Quote Originally Posted by Gere View Post
    Quote Originally Posted by MagiMaster View Post
    Working that out on paper would be an interesting mathematical exercise.
    Working that out on paper would be pain in the ass.
    I was about to disagree with you, but then I tried it myself, and yeah, it's a pain. It's not actually too hard to set the problem up (if you know quite a bit about cones and ellipses), but actually solving it gets pretty tedious.
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  20. #19  
    Forum Bachelors Degree GoldenRatio's Avatar
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    Quote Originally Posted by pineapples View Post
    Quote Originally Posted by pineapples View Post
    As a (lay)man of science, but more a gambling man- I’d hazard a guess and say the base end of the cone would float on top because it would likely contain more trapped air than the tip end of the cone? I’m fairly 50/50 on this!
    Actually, I’m thinking it’ll simply float on its side for the same reasoning.
    Agreed, Its going to float on its side, at a slight angle with just the tip pointing to the sky, the degree that the tip will point upward will depend on how big the coned piece of ice is. In terms of width, length, & overall mass.

    A long, slender cone like an icicle will float fairly horizontally, with only a few degrees tilt. A short pyramid shaped cone will have much more tilt. Its also going to depend if we are talking an ice cube size, a basketball size or straight up iceberg size as mentioned. As the ice will have to find the equilibrium between density in the water & weight of the ice above water pushing it down.

    Edit: give me better dimensions than "coned shaped ice" for me to work out a better solution for you.

    Edit again: dyslexia kicked in on my brain there. Ment to say the point would be pointing down, not up. everything else correct just reverse it ^.^
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