You stand on the frictional platform which is rotating at 2.0 rev/s. Your arms are outstretched, and you hold a heavy weight in every hand. The moment of inertia of you, the extended weights, and the platform is around 7.8 kg • m2. If you pull the weights in toward your body, the moment of inertia reduces to 3.6 kg • m2.
(i) Determine the resultant angular speed of the platform?
(ii) Determine the change in kinetic energy of the system?
(iii) Where did this raise in energy come from? (Choose all that apply.)