While rehearsing for a “Christmas Physics Show” to which I was invited by the Institute of Physics of Opole University, I recalled how excited I was, as a student, to observe a glass of water being swung and the water's surface always staying parallel to the platform. I also remembered a leaning block not flipping over when sliding down an inclined, almost frictionless, plane. But what about a ball? Isn't it possible to demonstrate a ball remaining at rest on a swinging platform (Fig. 1)?
I, along with Andrzej Wolf and Andrzej Trzebuniak, both professional physicists from the Institute, realized that it would be hard to demonstrate. A “frictionless” swing would have to be precisely leveled in order to get the expected result.
It turned out that years ago a solid, high-quality swing had been constructed in the Institute workshop. We expected that a 0.4-kg steel ball would be...
