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Homework Help: Figure out how far up the incline of the hill the box slides.

  1. Sep 22, 2013 #1
    1. The problem statement, all variables and given/known data
    At the bottom of a hill, a box has a speed of 15 m/s. The hill forms an angle of 30 degrees with the horizontal. How far up the incline of the hill does the box slide?

    2. Relevant equations
    My answer:
    d = (vf2 + vi2) / 2a

    3. The attempt at a solution
    vi = 15 m/s
    vf = 0 m/s

    a = (-9.81 m/s2)*cos(30) = -8.49 m/s2

    d = 13.25 m

    However, the answer key says d = 23 m. This is the answer if you use a = (9.81 m/s^2)*sin(30) instead. Help?
  2. jcsd
  3. Sep 22, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    What's the component of gravity acting down the incline? That's where sinθ comes in.
  4. Sep 22, 2013 #3
    Oops, I had 30 degrees in the wrong corner of the triangle. It works now! Thanks.
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