A student sits on a freely rotating stool holding the two dumbbells, each having mass 3.08 kg. If his arms are extended horizontally, the dumbbells are around 1.06 m from the axis of rotation and the student rotates with the angular speed of 0.759 rad/s. The moment of inertia of the student plus stool is around 2.74 kg • m2 and is supposed to be constant. The student pulls the dumbbells inward horizontally to a position 0.305 m from the rotation axis.
Determine the kinetic energy of the rotating system before and after he pulls the dumbbells inward.