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Angular momentum

  1. Apr 6, 2009 #1
    1. The problem statement, all variables and given/known data
    A device with 8 balls each with a mass of 0.8 kg is attached to spokes with length of 1.4 m, radius of 0.7 m. A lump of clay of 0.2 kg falls on the at the location shown and is attached to a ball at 45 degree angle. Before the impact, the clay was at a speed of 5 m/s. It moves counterclockwise with a angular speed of 0.08 radians/s.

    What is the angular momentum of the system of the clay and devise?

    2. Relevant equations
    Ldevice = 1/2*M*R2
    Lclay = r*p
    Lsystem = Ldevice + Lsystem

    3. The attempt at a solution
    For the device, is the mass 8*0.08?
    Also for the clay, is r just the radius?
    Is this the right way to do this?
  2. jcsd
  3. Apr 6, 2009 #2


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    Homework Helper

    First of all there is no diagram and so whichever of the spokes it lands on is not given. But said you angular momentum of the system is made of two parts.

    L of spokes/blocks = I * ω

    L of clay = r X P

    But the r here is not the R of the spokes. It will be R*√2/2 which is the distance from the center along the axis that is ⊥ to the downward direction of P

    Your I for the masses is apparently 8*.8*m*1.42
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