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A disc-shaped merry-go-round has a mass of 100 kg and a radius of 1.60 m and...

A disc-shaped merry-go-round has a mass of 100 kg and a radius of 1.60 m and is initially spinning at 20.0 rpm, with a 33-kg child sitting at its center. The child then walks out to the edge of the disc. (a) Find the initial and final moments of inertia of the system (disc + child), treating the child as a point particle. (b) State why the system’s angular momentum is conserved. (You can assume that the axis of the disc is frictionless.) (c) Find the initial and final kinetic energies of the system. (d) State the physical reason for the change in kinetic energy. (I.e., what force does the work that causes the kinetic energy to change?)

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