Compare torsional behavior of solid and hollow shafts of equal weight.

For equal weight, a hollow shaft has a larger diameter and higher polar moment of inertia, making it stronger and stiffer in torsion. The torsion equation T/J = τ/r = Gθ/L shows that for equal torque, hollow shafts have lower maximum shear stress. Weight savings can reach 25-30% for the same strength. Hollow shafts are preferred in automotive axles and aerospace applications.