21. The figure shows a rigid structure consisting of a circular hoop of radius R and mass m, and asquare made of four thin bars, each of length R and mass m. The rigid structure rotates at a constantspeed about a vertical axis, with a period of rotation of 2.5 s. Assuming R=0.5 m and m=2.0 kg,calculate the structure’s rotational inertial about the axis of rotation. 

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