Think about this stuff with regards to the Pulley Diameter at the end of the Endless Belt apparatus . . . . In addition consider that you ain't no skater on "frictionless" ice where no "torque" (lag pressure) is being applied. You hopefully still have thrust on your side. But again consider the amount of loading you place on the system in this regard and how much certain different pulley diameters can accomodate.
The moment of inertia of an object about a given axis describes how difficult it is to change its angular motion about that axis. For example, consider two discs of the same mass, one large and one small in radius. Assuming that there is uniform thickness and mass distribution, the larger radius disc requires more effort to accelerate it (i.e. change its angular motion) because its mass is effectively distributed further from its axis of rotation. Conversely, the smaller radius disc takes less effort to accelerate it because its mass is distributed closer to its axis of rotation. Quantitatively, the larger disc has a larger moment of inertia, whereas the smaller disc has a smaller moment of inertia.
The moment of inertia has two forms, a scalar form I (used when the axis of rotation is known) and a more general tensor form that does not require knowing the axis of rotation. The scalar moment of inertia I is often called simply the "moment of inertia".
The moment of inertia can also be called the mass moment of inertia (especially by mechanical engineers) to avoid confusion with the second moment of area, which is sometimes called the moment of inertia (especially by structural engineers) and denoted by the same symbol I. The easiest way to differentiate these quantities is through their units.
In addition, the moment of inertia should not be confused with the polar moment of inertia, which is a measure of an object's ability to resist torsion (twisting).
Conservation of angular momentum allows athletes such as ice skaters, divers, and gymnasts to manipulate their rotation by altering their moment of inertia. For example, consider spinning ice skaters who pull in their arms. Since the ice is nearly frictionless, the angular momentum should stay constant during their spin. When they pull in their arms, the skaters concentrate their mass closer to the rotation axis, decreasing their moment of inertia. To keep the angular momentum constant, the angular velocity ω increases, resulting in a faster spin
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