¶ Rotation of Spheres
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Cross Reference
Rotation of Spheres:
"A single sphere is free to rotate in any direction.
"Two spheres although free to rotate in any direction must do so cooperatively, assuming no slippage between the touching spheres.
"Three spheres can only rotate cooperatively about respective axes which are parallel to the edges of the equilateral triangle defined by joining the sphere centers, that is, each sphere rotates toward the center of the triangle.
“Four spheres lock together. No rotation is possible, making the minimum stable system: the tetrahedron.”
Cite SYNERGETICS ILLUSTRATIONS caption #8, 1967
¶ Cross-References
- Illustration #8
