The Physics of Bubbles Did you ever wonder why bubbles are round? It's easy. The answer is that surface tension causes the liquid film to pull itself into the most compact shape possible, which is a ball. Surface tension???? What's that? You can click and go to the glossary page or you can learn all about it like we did, by playing with bubbles.
A bubble is like a balloon filled with water. You can add more amore water but at some time the balloon will burst. A bubble is also like a drop of water hanging from a faucet. Picture of drop collecting at the end of the faucet. It hangs, growing bigger and bigger Finally, after it has reached a certain size it falls off. The water hangs because something like an elastic bag holds it together until it gets too heavy. There really isn't a bag, it is like an invisible skin. This something is called surface tension Water molecules under the surface are strongly attracted to each other . Surface water moleculeshowever, are not attracted to the air molecules above them. They are attracted downward and inward toward the rest of the water. This surface tension creates the EFFECT of a "skin" on the water. Different liquids have skins that are stronger or weaker. Alcohol is a liquid with a weaker surface tension than water. Soapy water has a surface tension that is stronger than water. You read the answer before, but now it will make sense. Surface tension causes the liquid to pull itself into the most compact shape possible - which is a ball. So the "air inside is held neatly in by the same force all around the bubble. ( At least until the bubble bursts)." Reference: HOW COME by Kathy Wollard, Workman Publishing, 1993: New York. For some real fun with bubbles, and lots of great activities, go to PROFESSOR BUBBLES OFFICIAL BUBBLES HOME PAGE. Then be sure to click BACK to return to our page. |
