Balancing Cups

These stainless steel drinking bowls are called 'Balance' by the German designer, Katja Hoeltermann, and are still sold by the German company Carl Mertens. W...

Here's the most curious physics toy from Germany, all about balance. They're two metal cups, they are the same in fact, but look how they're made; it's got a much thicker piece of metal on this side and much thinner on this side. Which is why when it lies on the table, it's got a completely semi-circular base, it lies so eccentrically. It won't lie level. Now if we fill it with water, the water will gather, well much more water will gather on the thin side than on the thicker side so it balances up. I think that's what will happen when we now fill with water very gently; we should get the thing to become almost level. [Filling cup with water] There she comes, wow. Now we'll try the other one. [Filling cup with water] I think it's going to spill over, but no it won't, it will correct itself. Oh, there she goes. What a wonderful demonstration of balance. Perfect.