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?

(In reply to re(2): spoiler by vswitchs)

Your solution was the first I had in mind, but then I thought that decreasing the surface tension with soap wouldn't really force the cork to float in the center. The cork would merely randomly float around, still being attracted by the border a little because there still is surface tension.

But thanks to your post, I now really wanted to know and I thought I should verify this experimentally. Not having had a cork handy, a bottle of red wine had to be sacrificed in the name of science. So I opened a nice Chianti Rufina 2003 and put the cork into a half-filled glass of water (I made sure none of the wine goes to waste, hicks, but unfortunately my girl friend doesn't drink so, hicks, apologies for any typos) Indeed, after overfilling the glass the cork swims toward the center as theoretically predicted.

Because everything is getting a bit blurry now and I am feeling kinda dizzy, apologies for not going more into the physics of this phenomenon. I'd rather go into bed now. Nighty.

Posted by JLo on 2006-10-03 15:51:25