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Finding the speed of a book against a vertical wall

  1. Sep 25, 2016 #1
    1. The problem statement, all variables and given/known data

    t09diQz.jpg
    the main question asks: "If the book is initially at rest, what is its speed after it has traveled 0.400 m up the wall?"
    2. Relevant equations
    ∑F = m*a
    vf2 = vi2 + 2 * a * d , when initial velocity is 0.
    3. The attempt at a solution
    So here's my free body diagram:
    kOUypje.jpg
    and out of that FBD I got these equations:
    ∑Fx=N−Fcos(60)=0
    ∑Fy=fk+Fsin(60)=ma

    I know that fk=μ(Fcos(60)) = μN

    Should i solve for the acceleration and then plug it in the kinematics equation to solve for final velocity? And are my equations and FBD right?
     
  2. jcsd
  3. Sep 25, 2016 #2

    cnh1995

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    The book is moving upward. Shouldn't the frictional force be downward then?
     
  4. Sep 25, 2016 #3
    Oh okay so Fsin60 - mg - fk then? I forgot to add the mg on my equation up there.
     
  5. Sep 25, 2016 #4

    cnh1995

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    Right.
     
  6. Sep 25, 2016 #5
    Ohh okay i didn't catch the "up" part on the question. So i can solve for acceleration now then given that equation?
     
  7. Sep 25, 2016 #6

    cnh1995

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    Yes. And then plug it in the kinematic equation
     
  8. Sep 25, 2016 #7
    Awesome. I did that and i got the right answer. Thanks a lot! :)
     
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