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Homework Help: I think this problem has problem

  1. Apr 19, 2013 #1
    Hi guys!!!! i'm a high school student in korea. I was doing homework then, i found that i couldnt understand sth.

    When i pull a rubber band, that will make rubber molecules equall but also make them hot.
    The problem said 'the entalpy of rubber band when you didnt pull has higher entalpy than you pulled'

    Buttttt i think that i worked to the band, so the heat was from work.
    It cant define the higher entalpy because of release of heat.

    Did i wrong?
  2. jcsd
  3. Apr 20, 2013 #2


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    Stretch the band and allow it to return to it's original temperature. When you relax the band heat flows into the band from it's surroundings. Therefore it's entalpy increases.
  4. Apr 20, 2013 #3


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    Staff: Mentor

    Hi wrrr95, http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    Actually, stretching makes them cold. You could concoct a crude refrigerator by stretching rubber bands.
    Last edited by a moderator: May 6, 2017
  5. Apr 20, 2013 #4


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