posted by applebottom .
A child of mass 40 kg stands beside a circular platform of mass 90 kg and radius 1.6 m spinning at 2.8 rad/s. Treat the platform as a disk. The child steps on the rim.
a) What is the new angular speed;
b) She then walks to the center and stay there. What is the angular velocity of the platform then?
c) What is the change in kinetic energy when she walks from the rim to the center of the platform?