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Implications of relativity

  1. May 31, 2015 #1
    1. The problem statement, all variables and given/known data
    A nuclear power generating station generates 3 x 10^9 W of power. How much mass does the plant convert into energy in one month (30 days)? Assume that the process is 100% efficient.

    2. The attempt at a solution
    m = E / c^2, E = P x t
    m = (3 x 10^9 W)(30 days) / (3 x 10^8 m/s) ^2
    = 1 x 10^-6 kg
     
  2. jcsd
  3. May 31, 2015 #2

    gneill

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    Staff: Mentor

    Watts are equivalent to Joules per second. You've multiplied by 30 days. The units of time are not the same... so what should you do about that?
     
  4. Jun 1, 2015 #3
    1 hr = 60 sec, 24 hr = 24 x 60 = 1440 s in a day, 1440 x 30 = 43200 s in 30 days
    thus, (3 x 10^9 W)(43200 s) / (3 x 10^8 m/s) ^2 = 1.44 x 10^-3 kg
     
  5. Jun 1, 2015 #4

    gneill

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    Staff: Mentor

    One hour is not 60 sec!
     
  6. Jun 1, 2015 #5
    Omg im so dumb lol, 60 min = 3600s, 86400 s in a day, 2,592,000 s in 30 days
    thus, (3 x 10^9 W)(2,592,000 s) / (3 x 10^8 m/s) ^2 = 0.0864 kg
     
  7. Jun 1, 2015 #6

    gneill

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    Staff: Mentor

    Huzzah! That's better! :smile:
     
  8. Jun 1, 2015 #7
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