Gere & Goodno — Torsion: Problem 3.11-4

3.11-4 A thin-walled steel tube of rectangular cross section (see figure) has centerline dimensions $b = 150 \text{ mm}$ and $h = 100 \text{ mm}$. The wall thickness $t$ is constant and equal to $6.0 \text{ mm}$. (a) Determine the shear stress in the tube due to a torque $T = 1650 \text{ N}\cdot\text{m}$. (b) Determine the angle of twist (in degrees) if the length $L$ of the tube is $1.2 \text{ m}$ and the shear modulus $G$ is $75 \text{ GPa}$.