physics student is sitting on a frictionless platform that is
rotating with an angular speed of ωi =
1.3 rad/s. His arms are outstretched, and he
is holding a heavy weight in each hand. The moment of inertia of
the student, the extended weights, and the platform about the
rotation axis is Ii =
10.8 kg·m2. When the
student pulls the weights inward toward his body, the moment of
inertia decreases to If =
6.4 kg·m2. What is the resulting
angular speed, ωf, of the platform?
By how much is the kinetic energy of the system increased?
(Think about where this increase in energy comes from!)