Beer & Johnston — Torsion: Problem 3.61

3.61 The mass moment of inertia of a gear is to be determined experimentally by using a torsional pendulum consisting of a 6-ft steel wire. Knowing that \(G = 11.2 \times 10^6\) psi, determine the diameter of the wire for which the torsional spring constant will be 4.27 lb·ft/rad.