A student sits on a freely rotating stool holding two dumbbells, each of mass 3.02 kg (see figure below). When his arms are extended horizontally (figure a), the dumbbells are 1.02 m from the axis of rotation and the student rotates with an angular speed of 0.758 rad/s. The moment of inertia of the student plus stool is 2.62 kg · m2 and is assumed to be constant. The student pulls the dumbbells inward horizontally to a position 0.299 m from the rotation axis (figure b).
(a) Find the new angular speed of the student.
rad/s
(b) Find the kinetic energy of the rotating system before and after he pulls the dumbbells inward.
Kbefore = J
Kafter = J