Snail Ball

A small, metallic gold ball just over 2 cm in diameter. Place it on the plastic channel which is slightly sloping, and you would expect it to roll down in the normal way. Well, this ball does roll, but it does so incredibly slowly. To an audience, it seems baffling why it should roll down a slope apparently in slow motion. You can pick the ball up, and it seems heavy, possibly solid. No clues if you shake it.

However inside the ball, which is actually hollow, there is a viscous liquid and a smaller ball which is very heavy. When the Snail Ball rolls slowly down an incline, it is the smaller, heavier ball inside that determines the pace, and this is slow because of the viscous liquid. Obviously the slope cannot be too extreme, or the ball will simply slide down it and the 'snail' action cannot work.