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Homework Help: Very simple entropy question

  1. Mar 23, 2014 #1
    1. The problem statement, all variables and given/known data
    The temperature at the surface of the Sun is approximately
    5 700 K, and the temperature at the surface of the
    Earth is approximately 290 K. What entropy change
    occurs when 1 000 J of energy is transferred by radiation
    from the Sun to the Earth?

    2. Relevant equations

    3. The attempt at a solution
    So I know how to solve this problem. My question is more about the sign than about the calculation.
    I left my answer of ΔS as negative, but the book lists it as positive. It seems to me like the change should be negative because the T is cooler on earth hence entropy should decrease within this closed system.
  2. jcsd
  3. Mar 23, 2014 #2

    Simon Bridge

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  4. Mar 23, 2014 #3
    Ah of course that makes sense! Since this is an irreversible process the entropy must increase.
    Thank you!
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