I’m completely stumped. My family and I rented a beach house last week as part of our vacation. On one of the shelves in the living room is one of those chrome and plastic visual pieces that they sell in places like Spencer’s in the mall.
It consists of a black rectangular base about 6"x1". There are two, thin, clear, plastic sheets mounted vertically on the base. These are about 3" high and 8" long. The top edge is cut so that they form a shallow V. They are parallel to each other and about 1" apart. There is a separate wheel-like piece which consists of a hub with two stubs sticking either side like an axle and three spokes, each with a diamond-shaped weight at the end of it.
You set the “wheel” on top of the plastic “walls” and it rolls merrily back and forth from one end to the other, eventually (one would assume) slowing down to the point where you need to set it going again. The point of my question is: That thing has been rolling non-stop since we moved in to the house 8 days ago without anybody touching it. It never gets lower. I can tell because on the right side, it rolls all the way to the stops at the end, just like it has since day one. It doesn’t roll as high on the left side, presumably because the shelf is not level.
Perhaps the wieghts in the end of the “wheel” have magnets in them, or maybe the base does. But other than increasing the downforce, it shouldn’t have any effect on the speed of the object, since any pull on a weight coming down will be counteracted by the pull on the weight going up on the other side. In the end, it should all come down to the friction of the axle on the plastic “walls”. Added to this is the friction of the hub when it rubs against the “walls,” since it doesn’t roll straight in the middle, but occasionally meanders from side to side.
So what’s the explanation? Do physics go on vacation like the rest of us? Or are the jumbo-sized Florida cockroaches playing tricks on me by keeping this thing going?