고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem 6.9-6

6.9-6 The cross section of a slit circular tube of constant thickness is shown in the figure. (a) Show that the distance \( e \) from the center of the circle to the shear center \( S \) is equal to \( 2r \) in the figure part a. (b) Find an expression for \( e \) if flanges with the same thickness as that of the tube are added, as shown in the figure part b.