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Dynamics Impulse problem mechanical engineering

  1. Apr 24, 2012 #1
    1. The problem statement, all variables and given/known data
    find tension in cable and velocity of B after 5 seconds. System released from rest. no slipping, neglect weight of pulley and cable.


    2. Relevant equations
    τ(t) = Iω
    Parallel axis theorem?
    3. The attempt at a solution

    Picture of problem: http://i49.tinypic.com/5ue7sx.jpg


    the question is R15-3, I attempted the problem by rotating the axes but i think that made me more confused. Once I do that, the tension on the wheel is still the same as the tension on the rope(not the X component?)

    Also my prof said to consider parallel axis theorem, but if I'm analyzing the rolling wheel, isn't the point of rotation at the bottom where it touches the ground?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 24, 2012 #2

    OldEngr63

    User Avatar
    Gold Member

    You can use the standard form for computing the MMOI for the cylinder about its own CM, but then, as you observed, the center of rotation is the point of contact, so you can use the parallel axis theorem to transfer to that center of rotation.

    The more difficult part of the problem is the kinematic relation between the rotation of the cylinder and the weight on the cord. You must establish this because the accelerations are coupled by this kinematic relation. There is only 1 degree of freedom here, and consequently 1 equation of motion to be determined. Good luck!
     
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