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Lose weight or train?

  1. Jan 26, 2009 #1
    EDIT -- I posted this here because I figured its more of a conceptual problem than a HW problem, but if people see otherwise, feel free to delete the post.

    I'm having troubles wrapping my head around this one (I've provided the example from my class notes below):

    My question -- how does a decrease in the mass of the rider increase his power producing ability by 18 W? Intuitively, I would think that a rider with lower mass will experience less resistive forces when riding (i.e., gravity when on an incline, kinetic friction) and so can sustain the same velocity as a heavier rider without applying as much force and, therefore, less power.

    From a physics standpoint, how does a mass decrease result in an increase in Power as this example suggests (taken from my class notes)?

    Last edited: Jan 26, 2009
  2. jcsd
  3. Jan 26, 2009 #2


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    "Rider"? Climber would be a better description, the riders weight is being treated as the opposing force in this problem.
  4. Jan 26, 2009 #3
    I dont think our bodies are that simple to derive power from the ratio of masses. It seems ridiculous. Even this 250 watt cannot be sustained forever. A cheetah-at it's max speed- should stop pursuing the deer within 40 seconds or so before it gets hyperthermia. :)
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