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Homework Help: Work done walking up a mountain

  1. Dec 28, 2016 #1
    • Poster has been reminded to use the Homework Help Template in schoowork posts here

    2. Relevant equations

    I used F=ma to calculate F and pythag theorem to calculate slope lengths

    3. The attempt at a solution

    On the left hand side (angle 35) the slope length is 636m, on the right hand side (angle 25) the slope length is 365m.

    Now, in my notes I know that F=ma and since there is an angle inbetween, to calculate work done the formula is:

    Work done = (F)(Cos,theta)(Distance)

    so we should use cos35 and cos 25 but on the videos and mark scheme they use sin instead of cos??

    Could someone explain why we use sin and not cos?
    Last edited: Dec 28, 2016
  2. jcsd
  3. Dec 28, 2016 #2

    Doc Al

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    Staff: Mentor

    Theta corresponds to what angle? (In the work formula.)
  4. Dec 28, 2016 #3
    the incline angle, so in this case it would be either 35 or 25, that's what I have in my notes
  5. Dec 28, 2016 #4

    Doc Al

    User Avatar

    Staff: Mentor

    In the formula for work, it's the angle between force (what's the force you're working against here?) and the displacement. (Not simply the angle of the incline, though it's surely related.)
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