Ring-a-round

How does the exhibit work?

Put the ring in the middle of the plate on its side and give it a firm twist.

What is the science behind it?

The ring gets gravitational energy (or potential energy) when you put it upright. If you then also give it a spin, the ring also gains kinetic energy (or energy of motion).

Because both the ring and the plate are very smooth, there is little friction. Therefore, only a very small amount of energy is converted into heat at each turn. The ring can therefore turn for a long time.

The ring will move up and down faster and faster, until the friction eventually makes the ring stop spinning.

(Little) friction on ice

You can enjoy skating, sliding or - less fun - slipping on it. But what exactly makes ice so slippery? Well, there is actually always a thin layer of water on the ice. This is because the top layer does not freeze. That ever-present layer of water reduces friction with your shoe or skate, making the ice slippery as a result.