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Ice flows and ice cubes

Discussion in 'General Chat' started by scrapbook, Sep 17, 2005.

  1. scrapbook

    scrapbook
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    I was watching Channel 4 news tonight and they had another one of those stories about melting ice flows etc etc in the north pole.

    Anyway to back up a point they were making in the story that when ice flows melt they do not raise the sea level they marked the water level in a glass of water iand then added 3 ice cubes.

    Speed the camera on a few hours after they have melted and the water level in the glass has not risen a mm....so who can explain to me why that is....I would have assumed the ice cubes melted to water and so would increase the water level in the glass.:confused:

    Try it yourselves!!
     
  2. damage

    damage
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    this is from memory of school physics

    so when an ice cube is in water the amount of water it displaces (ie how much of the ice cube is under the water) is equal to the weight of the ice cube.

    we know when water freezes it increases in volume
    (though weight remains same) so explaining why some of the ice cube is above the water (cos only the volume of the water pre freezing needs to be displaced)
    alternatively, when freezing, the mass stays same, volume increases, therefore density decreases, so less than water
    so floats



    when the ice melts it will return to the same volume of water as before it froze, which was exactly how much water was displaced when it was ice so the water level will stay the same

    not well explained, was just typing as i think, so open to corrections or clarifications

    but basically do some diagrams and it might make sense!
     
  3. scrapbook

    scrapbook
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    does thay explain the fact they marked the level of the water before they put the ice cubes in??? well i think they did
     
  4. vonhosen

    vonhosen
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    Are you sure they didn't mark the glass after they had put the ice cubes in ?

    The levels would rise when you put them in because of displacement (remember Archimedes), but the melting would have no effect because the ice would have the same mass whether it was in solid or liquid form.

    The water or sea levels will only rise if something new is added, not something that is already floating in it melts.

    EDIT
    pipped to the post
     
  5. scrapbook

    scrapbook
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    Hmmm not sure now, annoyed i cant remember properly!

    I will be out with the glass of water and ice pops tomorrow now!!
     
  6. bowenjones

    bowenjones
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    So when some scientists say that sea levels will rise due to the ice caps melting because of global warming, do they actually mean land bourne ice only :confused:
     
  7. scrapbook

    scrapbook
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    I believe that was the gist of the story yes.
     
  8. bowenjones

    bowenjones
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    I'm glad I live up north then as there is no land mass under the arctic and therefore we should be ok. Wouldn't like to be living near antarctica though ;)
     
  9. Steven

    Steven
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    Lets leave it for our unfortunate descendants who will deal with this in a couple of hundred years....the science speak hurts my head
     
  10. scrapbook

    scrapbook
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    You mean our kids kids??:eek:

    To quote a Kenyan Proverb...

    The environment is not given to us by our parents, but lent to us by our children!
     
  11. Steven

    Steven
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    Ah OK. But what can we do, when on the other hand, as witnessed earlier this week, man's dependance on oil?
     
  12. Garrett

    Garrett
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    A solid body immersed in waster will displace its same amount of volume.
    A weight placed on something that stays aloft will displace the same weight of water.
     

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