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Homework Help: Dynamics problem

  1. Dec 20, 2008 #1
    1. The problem statement, all variables and given/known data
    I drew this to make it easier to understand:
    http://img142.imageshack.us/img142/2729/problemagc0.th.jpg [Broken]
    E (mass: 400g) can move along the semicircle.
    ABCD is a plate rotating around (AD) axis at constant speed (14 rad/s).
    Coefficients of friction are 0.35 (static) and 0.25 (dynamic).
    I need to find out whether E will move for θ = 80º and for θ = 40º. Also I need to find the module and direction of the friction force for t0.

    2. Relevant equations

    3. The attempt at a solution
    I applied Newton's second law.
    Σ Fext = mg + N1 + N2 + f
    mg is E's weight
    N1 is the normal force in the (ABC) plane
    N2 is the normal force perpendicular to the (ABC) plane
    f is the friction force
    I did this also so that you understand what I mean -just in case... :)
    http://img88.imageshack.us/img88/4488/esquemabr8.th.jpg [Broken]

    Then I think I must use:
    aE = aO + aE/O + ωx(ωxOE) + αxOE + 2ωxvE/O
    α = dω/dt = 0
    ω = 14 j
    OE = (0.65 - sin(θ)*0.25) i

    I hope you can help me out here. Thanks a lot!
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Dec 21, 2008 #2
    Bump, anyone?
    Thanks again.
  4. Dec 22, 2008 #3
    Bump, please give me a hand...
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