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Homework Help: Angular Acceleration Using Work and Energy Principals

  1. May 23, 2012 #1
    1. The problem statement, all variables and given/known data

    The chain of a workshop crane is 50 m long and has a mass of 3 kg/m. It is partially wound on a drum and the effective radius from the axis of the drum to the chain centre line is 0.2 m. The drum itself, including shaft and gear wheel has a mass of 100 kg and has a radius of gyration of 0.15 m. A steel block with a mass of 500 kg is to be lifted from a point 20 m below the level of the axis of the drum. If a torque of 1.3 kNm is applied to the drum, what will be the initial vertical acceleration of the steel block?

    2. Relevant equations

    P.E = mgh
    K.E = 1/2mv^2
    I = mK^2
    Torque = radius * Force
    Work Done = F*distance
    F=mass* acceleration

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. May 24, 2012 #2
    I have just found out it is meant to be using angular and linear momentum but I a m still stuck:

    Sum of moments = angular momentum

    Momentum = Inertia*angular velocity + mass*velocity*radius
  4. May 25, 2012 #3
    Sum of moments is not angular momentum. Sum of moments is the moment of inertia multiplied by the angular acceleration.
  5. May 25, 2012 #4
    I solved it many thanks for your help.
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