Swinging bob toy with middle bob having non-cylindrically symmetric weight distribution

摘要

A swinging bob toy having a middle bob with a non-cylindrically symmetric internal structure. The center of mass is located near the middle of the bore axis, and the percentage azimuthal variation V in the moment of inertia I about an axis in the equatorial plane, given by V=100x[I(phimax)-I(phimin)]/I(phimax), is minimized, for instance by positioning the internal components to produce a weight distribution with n-fold symmetry, where n>=3. In one preferred embodiment, the bobs are equipped with lights powered by on-board batteries. Flat cylindrical batteries are mounted on an equatorial circuit board with their axes of symmetry perpendicular to the bore axis. To allow battery replacement, the top and bottom halves of each bob are removably attached by screw-secured posts parallel to, but offset from, the bore axis. An on/off switch is accessible via a small aperture through a transparent outer shell. In one preferred embodiment, the lights flash at a frequency which is not visible when the bobs are stationary, but visible when the bobs are in motion.