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MCAT Question Confusion

  1. May 10, 2009 #1
    A girl riding her bicycle up a steep hill decides to save energy by zigzagging rather than riding straight up. Ignoring friction, her strategy will:

    A. require the same amount of energy but less force on the pedals
    B.
    C.
    D.

    I missed this question and when I saw the correct answer, I couldn't entirely understand why the the energy remains the same. Since dE = F*D, and she has more distance to travel (to the top of the hill) shouldn't energy increase?

    Edit: I understand the force is decreased by the same factor distance increases, making energy the same. But what about the increased distance to bike up the hill? Though I think I may be reading too deeply into the question making it more difficult, I'm not satisfied with the MCAT answer. Perhaps someone could correct my reasoning.
     
    Last edited: May 10, 2009
  2. jcsd
  3. May 10, 2009 #2
    Gravitational Potential Energy is independent of the path.
     
  4. May 10, 2009 #3

    Pengwuino

    User Avatar
    Gold Member

    Didn't you just answer your own question?

    On a side note, since you're ignoring friction, a non-conservative force, your system is a conservative system. Thus, the path one takes has no bearing on how much energy is expended to get up there. You're simply dealing with an initial energy and a final energy; in this problems case, potential energies.
     
  5. May 10, 2009 #4
    Thanks, I've got it now. Somehow I completely overlooked the fact that, friction neglected, the system would be conservative. I mean, from a "practical" standpoint from which I based my thought process on when I encountered the question, it's just hard to believe any sane person would want to bike up a hill like that, believing they could conserve energy.
     
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