July 30, 2004
Science Day
Yesterday Trevor and I spent some time after school working on a science experiment. We learned a little about how water molecules stick to each other and to the surface of other things using cohesion and adhesion.
The experiment included a large plastic test tube filled to the brim with water. Then we took paper clips one at a time and dropped them into the tube.
As expected, the paper clips displace the water, but it does not actually spill over the edge of the tube. As the tube is filled with more and more clips the water is being displaced. The cohesion of the water molecules to each other and the surface tension causes the water to bow out and make a solid bubble at the top of the tube.
We were able to fill the tube half full of clips before the pressure of the water below the top of the tuber overcame the surface tension at the top. An excellent lesson in science. Or as Trevor described it "cool dude"!