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Homework Help: Relative velocities of rigid bodies

  1. Oct 29, 2007 #1
    1. The problem statement, all variables and given/known data

    A triangular body changes orientation as the suspporting links rotate. At the moment shown, theta = 90 deg, theta_dot = 5 rad/s, and beta = 45 deg. Determine vA and the angular velocity of the triangular body.
    rB/C = 2j cm and rB/A = 5i cm

    Points E and D are fixed. theta is the angle made between horizontal and BE. beta is angle made between horizontal and AD.

    2. Relevant equations

    vB = vE + w x rB/E
    vB = vA + w x rB/A

    3. The attempt at a solution

    vB=vE + w x rB/E
    vB=0 + 5k x 2[]j[/b]

    vB=vA + w x rB/A
    -10i = vA + w x 5j

    I am stuck at this point because I am not sure if I should use theta_dot for this w because AD is at a different angle (beta). And if I do need to use a different w (which would be beta_dot how would I find it without knowing the length of AD.
    Last edited: Oct 30, 2007
  2. jcsd
  3. Oct 30, 2007 #2

    Shooting Star

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    Where's the diagram?
  4. Oct 30, 2007 #3
    ya.. plz if diagram is to be provided.. do not omit it.
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