Beer & Johnston — Torsion: Problem 3.146

3.146 A sheet-metal strip 6 in. wide and 0.12 in. thick is to be formed into a tube of rectangular cross section. Knowing that \(\tau_{\text{all}} = 4 \text{ ksi}\), determine the largest torque that can be applied to the tube when (a) \(w = 1.5 \text{ in.}\), (b) \(w = 1.2 \text{ in.}\), (c) \(w = 1 \text{ in.}\)