Consider the following simple experiment. Get a can of Diet Coke and a can of Classic Coke. Diet 7Up and & 7Up will work as well. Fill a large pot or basin with water. Place both cans in the water. Something interesting happens. Diet Coke floats while Classic Coke sinks. There is a simple explanation for why this happens. Why does Diet Coke float?
(Image courtesy of University of Wisconsin, 2008)