A uniform, solid disk with mass m and radius R is pivoted about a horizontal axis through its center. A small object of the same
mass m is glued to the rim of the disk. If the disk is released from rest with small object at the end of a horizontal radius, find the angular speed when the small object is directly below the axis.
According to the law of the conservation of energy, the gravitational potential energy of the physical system will be converted into rotational kinetic energy. So, we have:
Is the moment of inertia of the system, that is the sum of the moments of inertia of the disk and the small object.