Here we go again:
the said material point equivalent to the body mass is rotating (or gyrating, whatever) about the axis, thus circumscribing a circle, and this circle, not surprisingly, has a radius. I'd be more puzzled if someone would call it a distance rather than a radius. So radius it is.
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Alexander Bausk
http://bausk.wordpress.com/about
Civil/Structural design & inspection engineer
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ONILAES Lab at PSACEA
Dnipropetrovsk, Ukraine
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