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Help finding coefficient of friction

  1. Nov 15, 2006 #1
    Hey, I was wondering if someone could help me with this statics problem.

    The question is: "The 1600kg car is just beginning to negotiate the 16* ramp. If the car has rear-wheel drive, determine the minimum coefficient fo static friction required at B.

    My FBD:
    attachment.php?attachmentid=8335&stc=1&d=1163575175.jpg

    The answer I keep getting is 0.395, but the book says Us = 0.365.

    I'm about to type up my work in a second
     

    Attached Files:

  2. jcsd
  3. Nov 15, 2006 #2
    [tex]\Sigma \vec{F}_{x} = \vec{f}_{B} - \vec{A} sin(16) = 0[/tex]
    [tex] \Sigma \vec{F}_{y} = \vec{B} + \vec{A} cos(16) - G = 0 [/tex]
    [tex] \Sigma \vec{M}_{B} = -1.475*G + 2.545*\vec{A} cos(16)[/tex]

    .....From moment equation, A = 9463N
    ....From Fy equation, B = 6599N
    ....From Fx equation, Fb = 2608N

    Using Fb = u*B, I get u = 0.395, which is not the correct answer. I'm not really sure what I'm doing wrong here.
     
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