100 g cube, 4 cm side. Initial COM height 350 mm: bottom clearance 330 mm. Released from rest. Gravity 9.81 m/s², nominal friction 0.4, timestep 1 ms, duration 1 s. PhysX restitution is zero; other stacks use their recorded soft-contact settings, not an assumed equivalent restitution coefficient.
Contact impulse is integrated native contact force. Net force includes gravity. Lowest-vertex height uses the full recorded orientation; negative values indicate overlap of the ideal box with z=0, not an engine's contact margin. No smoothing or peak normalization.
