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Homework Help: Simple Unit Analysis

  1. Mar 1, 2014 #1
    1. The problem statement, all variables and given/known data

    $$Let\quad n\quad =\quad the\quad number\quad of\quad hours\quad I\quad run\quad a\quad 40\quad kilowatt\quad generator.\\ Assume\quad that\quad it\quad costs\quad $0.08\quad for\quad 1\quad kWh.\\ Revenue\quad from\quad generator=\frac { $0.08 }{ kW\cdot hours } \quad (40\quad kW)\quad (n\quad hours)\\ =$3.2n\\ \\ Suppose\quad I\quad want\quad to\quad make\quad $6.40\quad from\quad the\quad generator.\\ $6.4=$3.2n\\ n=2$$

    2. Relevant equations

    3. The attempt at a solution

    What am I doing wrong? Why isn't n in hours?
  2. jcsd
  3. Mar 1, 2014 #2


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    Because when you write time=n*hours, the units are in the "hours" part and n itself is dimensionless. If you the units to be included in 'n' just write time=n.
  4. Mar 1, 2014 #3
    Ah, got it. Thanks.
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