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Fusion and Einstein

  1. Mar 9, 2014 #1
    1. The problem statement, all variables and given/known data
    The energy output of an average person is about 121 Watts. Suppose the average human has a mass of 80 kg and it could run on fusion power by converting only .7% of its mass into energy.
    1) how much energy would be available to the body through fusion?
    2) How long could the body operate on fusion power (in years)?


    2. Relevant equations
    E=mc2


    3. The attempt at a solution
    Question involves 1)...i completed the problem, but realized that i may have made an error. in the first step i multiplied 80kg by .007 or .7% to get a value of .56 kg that could be used in fusion. I then plugged that into E=mc^2 and calculated a value of 5.04x10^16 J. Now does anyone think that for one i am instead being asked to calculate what energy is available if the average human could use its whole weight (80Kgs) in fusion? The rest of my work is bellow i would greatly appreciate if someone could give it a once over! thanks pf!


    unknown burned = 121W/5.04x10^16J/kg = approx. 2.401x10^-15 kg/s

    lifetime=(1.00)(80kg/2.401x10^-15 kg/s) = approx. 3.332x10^16s

    answer: 1.06x10^9 years
     
  2. jcsd
  3. Mar 9, 2014 #2

    Simon Bridge

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    Relax - the problem is assuming that 80kg of hydrogen fuel is available to power the body.
    In 4H->He fusion, only 0.7% of the proton mass is converted to energy - then all the fuel is converted into He: none left to burn.
     
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