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B How can this thermodynamic phenomenon be explained

  1. May 6, 2018 #1
    Hi there.

    Earlier today I decided to pull out ice cream from the freezer. It is a magnum-type ice-cream and comes in a plastic wrapper.

    Once I opened the wrapper and removed the ice cream, I left the wrapper on the kitchen table and noticed something rather bizzarre (to me at least). Everytime I placed a warmer object near the wrapper (I tried my hand, Tv-remote, metal fork and coffee coaster) within minutes of it being out of the freezer, the cold wrapper would tilt towards the object, and then hold onto it like a weak magnet. It was really weird seeing the packaging tilt towards my hand given that the separation between my hand and the packaging was roughly 1cm. It was fairly easy to remove the packaging from my hand.

    I would be really grateful if somebody could explain this to me.
  2. jcsd
  3. May 6, 2018 #2
    What if you placed a colder object near it. Would it also tilt for that?
  4. May 6, 2018 #3
    Ah shoot! I forgot to test that properly. I realised that I should have done so before posting. Sorry.

    edit: Actually I do recall testing it although not as thoroughly as with my hand. I tested it using the ice cream bar itself. I can confirm that it did not tilt for it, but I did not carry out any repeats so I can't be sure.
  5. May 6, 2018 #4
    I was thinking that it might be a static electricity effect.
  6. May 7, 2018 #5
    Interesting.After repeated testing today I can confirm that it does gravitate towards a cold object. When it didn't yesterday that must have been a one off.

    Please explain how static electricity would produce this effect

    Edit: I suppose it isn't actually thermodynamic if the cold wrapper tilts towards hot and cold objects
  7. May 7, 2018 #6


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    If you want to test if there is a temperature effect, you might want to use a much stronger heat source, like a light bulb or lighter, to exaggerate the effects.
    There could be something going on like a bimetallic strip. One side of the plastic may get warmer than the other side, and cause it to curl.

    If you want to test for static effects, you could try stroking the plastic with wool or something.
  8. May 7, 2018 #7
    I'll try that out over the coming few days. Should be interesting
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