Turntable Physics Question?

Question

A large turntable rotates about a fixed vertical axis, making one revolution in a time of T. The moment of inertia of the turntable about this axis is I. A child with a mass of m, initially standing at the center of the turntable, runs out along a radius.

What is the angular speed of the turntable when the child is a distance of R from the center? (Assume that you can treat the child as a particle.)

Answer 1

The moment of inertia of the turntable plus the child at radias R is I + m*R^2. Setting up the equation of conservation of momentum
I*(1 rev/T) = (I + m*R^2)*w Solve for w.