Question

A 129-kg horizontal platform is a uniform disk of radius 1.51 m and can rotate about the vertical axis through its center. A 67.5-kg person stands on the platform at a distance of 1.09 m from the center and a 25.3-kg dog sits on the platform near the person, 1.37 m from the center. Find the moment of inertia of this system, consisting of the platform and its population, with respect to the axis.

Answer 1

net moment of inertia = MR² /2 + m_p d_p² + m_d d_d²

= 129 X 1.51² /2 + 67.5 X 1.09² + 25.3 X 1.37²

= 274.75 kg-m²