It’s strange but true that a cork will not stay in the center of a glass of water. Instead it will slowly drift over to the side of the glass, where it will remain. There is, however, a simple way to make the cork remain floating in the center of the glass.
(Swirling the water is not the answer.)
August 8th, 2011 | Category: 
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remove the water
add soap to water…so due to surface tension it remains at center
Great guesses, but not what we’re looking for.
Keep guessing.
put a stick through the cork and rest the stick on the edge of the glass and it will stay in the middle.
Not the answer we were looking for, but it sounds like it would work!
Keep guessing.
hold the cork In the centre of the cup.
No, keep trying.
Tie a string to the cork and duck tape it to the inside of the glass
Sorry, no duct tape allowed. Keep guessing.
The cork drifts over to the side because the side is where the highest point of the water is (the water clings to the glass). Thus, all you have to do is fill the glass of water to the absolute top. The water will form a little dome-shaped thingy in the center (there’s a scientific name for it, but I forgot what it is), so it makes the center the highest point of the water. So the cork will stay there.
Is that it?
That is exactly it!
Fill the glass nearly to the top and place the cork. Now add just a little more water so that the water forms a convex shape without overflowing. The cork will seek the highest point which is the center of the glass.
Great job. You’re today’s winner.
Add teaspoons of water until the cork stays in the middle. It seeks the highest point of the water ^_^.