The South Tower's Top Disintegrated as it Fell
- The curvature of the wall shows about 30 stories above crash zone
had shattered less than 2 seconds into the collapse
- Top did not rotate about fulcrum,
rather it rotated freely about a changing axis.
- Angular momentum of the tipping top vanished.
Only the disappearance of the moment of inertia through the
breakup of the top can explain this.
Frames of NBC video at one-second intervals: