Part 1
A student sits on a rotating stool holding two 1 kg objects. When his arms are extended horizontally, the objects are 0.9 m from the axis of rotation, and he rotates with angular speed of 0.61 rad/sec. The moment of iner- tia of the student plus the stool is 6 kgm² and is assumed to be constant. The student then pulls the objects horizontally to a radius 0.39 m from the rotation axis.
Part 2
Calculate the change in kinetic energy of the system. Answer in units of J.