You stand on a frictional platform that is rotating at 1.3 rev/s. Your arms are outstretched, and you hold a heavy weight in each hand. The moment of inertia of you, the extended weights, and the platform is 8.6 kg · m2. When you pull the weights in toward your body, the moment of inertia decreases to 4.4 kg · m2.
(a) What is the resulting angular speed of the platform?
rev/s
(b) What is the change in kinetic energy of the system?
J
(c) Where did this increase in energy come from? (Select all that apply.)