A Christmas ornament made from a thin hollow glass sphere hangs from a thin wire of negligible mass. It is observed to oscillate with a frequency of \(2.50\,\text{Hz}\) in a city where \(g = 9.80\,\text{m/s}^2\). What is the radius of the ornament? The moment of inertia of the ornament is given by \(I = \dfrac{5}{3} mr^2\).