A person with weights on a rotating platform (1.5 points)
In class, we did the demonstration that the speed of rotation depends on the angular momentum, which changes when the location of the mass is changing even though the total mass stays the same. In the figure below, a person stands on a rotating platform holding a mass m = 4 kg in each hand. The moment of inertia of the person and the platform is I = 0.4 kg-m and the moment of inertia of each mass about the vertical axis through its center of mass is Im = 0.001 kg-m. If the person's angular velocity with her arms extended to r = 0.6 m is = 1 revolution per second, what is her angular velocity when she pulls the masses inward to r = 0.2 m? For the calculations, assume that the moment of inertia for the person is the same with arms extended and arms close to her body (i.e., only the moment of inertia of the masses accounts for all of the difference) and neglect friction in the rotating platform.