To finalize this problem, note that the initial configuration
in this example is the same as that in Example 10.10. In Ex-
ample 10.10, however, we could only find the initial angular
acceleration of the rod. We cannot use this and the kine-
matic equations to find the angular speed of the rod at its
lowest point because the angular acceleration is not con-
stant. Applying an energy approach in the current example
allows us to find something that we cannot in Example 10.10.