Step 1: Understand restoring forces.
Heave (vertical motion) and Pitch (rotation about transverse axis) have inherent restoring forces due to buoyancy and weight acting through different points.
Step 2: Surge and sway.
Surge (longitudinal) and sway (lateral) motions do not inherently have restoring forces unless influenced by external constraints.
Match the non-dimensional numbers in Column 1 with the corresponding definitions in Column 2:
