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Helicoid

The Screw-in Effect

As the surface spins, it appears to move linearly upward. This apparently translational motion can be considered as an illusion (barber-pole illusion) as well as a mechanism to generate translational force from rotation like in screw threads, twist drill bits, Archimedean screws, and screw propellers. This effect shows the relativity between rotational and translational transformations. This is the 3D version of the Spiral Ripple Effect. See the Spiral Zooming Effect for the relativity between rotational and scaling transformations.