728. Why does a can of Diet Coke float on water while a can of regular Coke sinks? Does that have to do with density and Archimedes' law? —AB, Riverside, CA
Because regular coke contains large amounts of dissolved sugar, it is much denser than water or than Diet Coke (which has far less dissolved material). Although even Diet Coke is denser than water, as is the aluminum in the can, a can of Diet Coke contains enough gas bubbles to lower its average density to just below that of water. According to Archimedes' law, an object with an average density less than that of the liquid in which it's submerged will float upward. A can of regular Coke has an average density that's greater than that of water, so it sinks.