Paper puzzles

Pondering this morning about the ways in which a brain might deal with moving images, pondering lighted upon spinning tops.

This led me to a clip on YouTube which reminded me that one can make elementary spinning tops with cocktail sticks and circles cut out of paper.

For which we carry the ingredients, with the results illustrated left.

Now if you spin the one top right, you get pink in the middle, shading down to white on the outside. Easily enough explained in terms of the density of colour being largest in the middle. While if you spin the one bottom middle, you get a set of concentric red circles. Which I have yet to explain at all and which is left as a puzzle for the reader.

In the meantime, I shall be testing various other patterns. Maybe even mixing up the colours.

PS: should you care to try for yourself, it is important to take care to get the cocktail stick in the middle, otherwise there is no spin. Drawing right angles to tangents with a ruler seems to work well enough, with no need to bother with a set square. Resultant pencil marks can be seen in the middle of the two red tops.