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.

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   \             /
    \           /
     \         /
      \_______/

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

Solution 1:
You keep pushing the cork toward the center with a stick

Solution 2:
You fill the glass so that the water level at the center is slightly higher than at the border of the glass. You'll have to "overfill" the glass which can be done due to the water's surface tension. I'd say this should work because the cork tends to swim up to the highest water level, since it is lighter than water. This would also explain why it keeps moving toward the glasses border when it is not completely filled; again due to surface tension the water level is slightly higher at the border of the glass.

Posted by JLo on 2006-10-02 08:29:14