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Homework Help: Specific Heat

  1. Jul 18, 2009 #1
    1. The problem statement, all variables and given/known data
    The Earth intercepts 1.27 x 10^17 W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 x 10^21 m3, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

    2. Relevant equations

    3. The attempt at a solution
    I just want to make sure that I did this correctly because the answer choices are all similar and vary by degrees of magnitude and I would like to avoid a simple mistake. Multiply the volume by 1000 to get the weight in kilograms, then multiply by 100, the temperature change. Multiply this by the specific heat. So:

    1.27 x 10^17 = 1.08 x 10^24 kg * 4186 * 100

    divide both sides by Q, gives a value in seconds. Convert to years which is approximately 113 years. Is this correct?
  2. jcsd
  3. Jul 18, 2009 #2


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    Homework Helper

    your equation should be

    (1.27 x 10^17)*t = 1.08 x 10^24 kg * 4186 * 100

    But other than that, it looks like it should be correct.
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