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Homework Help: Thermodynamics weightlifter

  1. Mar 29, 2008 #1
    1. The problem statement, all variables and given/known data
    A weight lifter manages to lift a 147 kg weight a distance of 1.1 m. Treat her as a thermodynamic system and find how much heat (in kcal) she must put out if her internal energy decreases by 3620 J during the lift.


    2. Relevant equations

    delta U=Q-W

    3. The attempt at a solution

    -3620= Q-(9.8*147*1.1)
    Q=-2035.34

    I was wondering wut the units of Q are? if it's in joules how do i convert to kcal?

    Thanks in advance!:smile:
     
  2. jcsd
  3. Mar 30, 2008 #2

    mgb_phys

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    Q is in Joules because you have used consistent metric units.
    A kCal is approx 4184J - it's the energy need to heat 1cc of water 1deg C.
     
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