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Can't find mistake on Spring/block Energy problem

  1. Dec 1, 2007 #1
    1. The problem statement, all variables and given/known data

    A 1.93 kg block situated on a rough incline with 38.2 angle is connected to a spring of negligible mass having a spring constant of 90 N/m.
    The block is released from rest when the spring is unstretched, and the pulley is frictionless. The block moves 10.9 cm down the incline before coming to rest.

    2. Relevant equations

    W = (fk cos 180)
    x= -[tex]\mu[/tex]k(mg cos theta)
    Wnc = ( KE + PEg + PE s)f - (KE + PEg + PEs)i

    3. The attempt at a solution

    I used the equations and combined them to get:
    -[tex]\mu[/tex]k(18.194N cos 38.2) (.109) = 0 + (18.194)(-.109sin 38.2)
    + .5(90 N/m)(.109^2)

    For my answer I got [tex]\mu[/tex]k = .4438645593
    It says that my answer is wrong and I can't find what I did wrong. I recalculated several times and still got the same answer. Can you help me? Thank you!
  2. jcsd
  3. Dec 1, 2007 #2
    I retried calculating, and I got a different answer that was close to the one I had already gotten, but it was still wrong.
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