Adjustable to favor rotation in either direction, or rattle and wobble with spin reversal! A Stanford dynamics professor invented this large, adjustable Celt as a demonstration for his students, and now you can have one too. This enhanced version of our favorite ancient toy has an adjustable bar that lets students vary the mass distribution for their own investigations. Experiment to see what orientation leads to the characteristic wobble-and-spin motion. A traditional Celt tends to spin in one direction, but the Dynamic Celt can be adjusted for simple spin in either direction, rocking that becomes spin, or rattling/wobble with spin-reversal! The included explanation will enhance any study of rotational motion, with information on moment of inertia, point of contact, and product of inertia.
