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Homework Help: Vertical Component Reactions given angular velocity

  1. Sep 4, 2014 #1
    1. The problem statement, all variables and given/known data

    A pendulum consists of a disk of mass M1, and a slender rod of M2 (which happens to be 0kg),.

    Determine the components of reaction that the pin O, exerts on the rod just as it passes the horizontal postion, at which time its angular velocity is ω.

    Know we know M1 = 15kg
    a which is radius of disk is 0.25m
    Rod is 1m
    g= 9.81m/s2

    2. Relevant equations


    I of rod=1/12 ML^2
    I of disk=1/4 MR^2+ 1/12 ML^2
    I=Icom + Mh^2
    T=2pi sqrt(I/Mgh)

    Now i don't know how I can fit in the angular velocity into this..
    3. The attempt at a solution

    Well I tried taking the moment from point O, and got 15*9.81 = 147.15N.
    I got the moment of inertia = 23.67kgm^2

    After that I am lost :(

    I have attached a picture, if that might help.

    THese problems are taking out of my dynamics text book :/

    Attached Files:

    Last edited: Sep 4, 2014
  2. jcsd
  3. Sep 4, 2014 #2

    I would assume it has to do something to do with the mass of the pendulum and the centripetal acceleration that the disk has due to its rotation. The force due to the rotation would be m*Omega^2*r. What about summing the force due to gravity and the one due to the centripetal acceleration? I hope this helps.
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