The video on the left shows the consequences of the
conservation of the angular momentum in the rotation of an ice skater,
Molly. When she is with her arms open, the moment of inertia is
greater than when turning with her arms close. In the pictures below,
the large vertical cylinder is of the same side in both pictures.
However, when she is initiating the turn, picture on the left, there are
three additional cylinder that can contribute to the moment of inertia.
Thus, the final moment of inertia is smaller than the initial moment of