The figure shows two thin-walled circular cross-sections with radius a and wall thickness t
a) Determine the torsion stiffness parameter Kclosed of the closed cross-section in Fig. a).
b) Determine the torsion stiffness parameter Kopen of the open cross-section in Fig. b).
c) Determine and comment on the torsion stiff-ness ratio Kopen/Kclosed.
