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How much perspiration must vaporize per hour to dissipate extra energy

  1. Jun 7, 2016 #1
    1. The problem statement, all variables and given/known data

    During the game, the metabolism of basketball players often increases by as much as 30.0 W. How much perspiration must a player vaporize per hour to dissipate this extra thermal energy? Assume that perspiration is simply pure water and that perspiration starts at temperature of 37 degrees celcius.

    2. Relevant equations

    Q=mcΔT
    Q=mHv

    3. The attempt at a solution

    Thermal energy to be dissipated in 1.00h is
    U=(30J/s)(3600s/hr)=108KJ/hr

    The amount of water this energy transmittes as heat would vaporize is,
    m=(1.08x10^5J)/(2.26X10^6J/kg)= 4.78x10^-2kg

    I'm not sure if I'm doing it correctly. I never used 37 degrees/
     
  2. jcsd
  3. Jun 8, 2016 #2

    mfb

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    2016 Award

    Staff: Mentor

    Did you have body temperatures in previous problems? Maybe the players start at lower temperatures?
     
  4. Jun 8, 2016 #3

    NascentOxygen

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    Staff: Mentor

    You use 37° when reading from tables to determine what value of ∆Hvap to use because it is not a fixed value across all temperatures, ∆Hvap falls slightly as temperature rises. http://www.thermexcel.com/english/tables/vap_eau.htm
     
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