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Homework Help: Reversibility of evaporating ice ball

  1. Oct 15, 2013 #1
    1. The problem statement, all variables and given/known data

    A ball of ice is thrown against a wall with such as speed than the ball of ice evaporates. Is this process reversible?

    2. Relevant equations

    if entropy doesn't change, process is reversible.

    3. The attempt at a solution

    I'm pretty darn sure the answer is no, but I am looking for qualitative reasons as to why this is not reversible.

    When my teacher went over reversibility, he said we should just run the process in (time) reverse and see if it makes sense.

    This situation does not make sense to me in reverse; water vapor will not spontaneously condense and freeze into an ice-ball that has some velocity.

    Can anyone offer a more concrete line of reasoning other than "this process doesnt make sense in reverse".
  2. jcsd
  3. Oct 15, 2013 #2

    D H

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    That's a fairly good qualitative description of irreversibility.

    One that's a bit more quantitative, how did Clausius characterize about the second law of thermodynamics?
  4. Oct 16, 2013 #3

    Andrew Mason

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    Since the forward process involves converting mechanical energy entirely into internal energy of the snow ball (ignoring any heating of the wall, air etc.), what would the reverse process involve? Following up on DH's suggestion, does the second law permit such a process to occur spontaneously?

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