A cylinder has inner and outer radii of #2 cm# and #5 cm#, respectively, and a mass of #5 kg#. If the cylinder's frequency of counterclockwise rotation about its center changes from #12 Hz# to #9 Hz#, by how much does its angular momentum change?
Let's assume this cylinder is uniform (which is very important).
Recall for a solid cylinder,
Moreover, recall angular momentum,
Now, let's derive the moment of inertia of this circular body,
which is generally constant in our calculations.
is the change in angular momentum given your data.
The angular momentum is
The mass of the cylinder is
The radii of the cylinder are
For the cylinder, the moment of inertia is
The change in angular velocity is
The change in angular momentum is