Take a glass that is partially filled with water and drop a cork into it. The cork won't float in the center, but keeps drifting to one side and attaching itself to the side of the glass.

\-------------------/
 \                 /
  \##-------------/
   \             /
    \           /
     \         /
      \_______/

Without swirling the water, how can you make the cork float in the center?

I've also seen a similar expanation for why cheerios in milk tend to stick together.

Each has its own bit of concave milk meniscus and so will tend to try to travel up that of its neighbors.  This holds them together.

Posted by Jer on 2006-10-02 10:50:49