A student sitting on a stool holds two weights, each of mass 10kg. When his arms are
extended horizontally, the weights are 1m from the axis of rotation and he rotates with
an angular speed of 2rad/sec. The moment of inertia of the student plus the stool is
8kg/m² and is assumed to be constant. If the student pulls the weights horizontally to
0.25m from the rotation axis, calculate:
a) The final angular speed of the system;
b) The change in mechanical energy of the system.