Top pipe falls

Much the same question was posed in the problems A triangle of cylinders (part 1) and A triangle of cylinders (part 2) , except that in these problems the cylinders were assumed solid. Thus we simply need to rerun the calculations of these two problems, replacing the moment of inertia $\tfrac12mr^2$ of a uniform disk of mass $m$ and radius $r$ with the moment of inertia $mr^2$ of a circular wire of mass $m$ and radius $r$ to obtain $a_1 = \tfrac{1}{13}g$ and $a_2 = \tfrac{1}{15}g$ , so that $\frac{a_1}{a_2} = \frac{15}{13}$ , making the answer $\boxed{28}$ .