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This week's LabZone activity
Nov. 5, 2003
Floating Flavor
How can you tell a regular soft drink from its diet form? Most likely, you can taste the difference. Although manufacturers of artificial sweeteners like to believe that their "sweetening" chemicals taste just like the real thing, they don't. Most people can detect a chemical aftertaste. There's another difference too. This one, however, is seen, not tasted.
Materials:
- a can of regular (sweetened with sugar) soft drink
- a can of diet soft drink
- fish tank or large bowl filled with water
To Do:
Place a can of regular soft drink in a fish tank or large bowl filled with water. Does it float or sink? Now place a can of soft drink in the bowl. What happens to this can?
The Science:
Floating is all about the balance of forces. The downward force that causes something to sink is called weight. The weight depends upon the amount of matter "stuffed" in an object. The upward force that causes something to rise is called buoyant force (or B.F.). The B.F. depends upon the amount of space the object takes up.
When the weight is greater than the B.F., the object sinks. When the B.F. is greater than the weight, the object floats. When the weight and B.F. are equal, the object remains at the same level (neutral buoyancy).
Regular soft drink is a solution of carbonated water, flavoring, and plenty of sugar. Since the drink's sugar is dissolved, you can't see it. You can, however, certainly taste it.
Like regular soft drink, the diet form contains carbonated water and flavoring. The sugar, however, is replaced by a small amount of an artificial sweetener. The taste of the substitute is so strong that very little is needed.
Cans of regular and diet soft drinks are almost neutral in buoyancy. The extra sugar in the regular soft drink, however, makes this can slightly heavier. The diet soft drink, although it has a small amount of artificial sweetener, lacks the sugar and is slightly lighter. Although the difference is small, it is significant enough to cause the can filled with regular soft drink to sink, while the can filled with the diet soft drink floats.
Check It Out!
Design a way to find out how much sugar (in grams) is added as a sweetener to regular soft drink.
Reprinted with permission of Sterling Publishing Co., Inc., from Awesome Experiments in Force & Motion by Michael DiSpezio. Text © 1998 by Michael A. DiSpezio and Catherine Leary (www.barnesandnoble.com).
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