SWINGING BOB TOY WITH MIDDLE BOB HAVING NON-CYLINDRICALLY SYMMETRIC WEIGHT DISTRIBUTION

摘要

A swinging bob toy (100) having a middle bob (311) with a non-cylindricallysymmetric internal structure. The center of mass is located near the middle ofthe bore axis (335), and the percentage azimuthal variation V in the moment ofinertia I) about an axis in the equatorial plane (337), given byV=100x[I(.PHI.max)-I(.PHI.min)]/I(.PHI.max), is minimized, for instance bypositioning the internal components to produce a weight distribution with n-fold symmetry, where n=3. In one preferred embodiment, the bobs (310, 311)are equipped with ligths (377) powered by on-board batteries (375). Flatcylindrical batteries are mounted on an equatorial circuit board (379) withtheir axes of symmetry perpendicular to the bore axis. To allow batteryreplacement, the top and bottom halves (311a, 311b) of each bob are removablyattached by screw-secured posts (371a, 371b) parallel to, but offset from, thebore axis. An on/off switch (380) is accessible via a small aperture through atransparent outer shell (351). In one preferred embodiment, the lights flash afrequency which is not visible when the bobs are stationary, but visible whenthe bobs are in motion.