Yesterday’s article gave some information on density and buoyancy. Today, a floating grape buoyancy science project will let students see the principles in action.
This demonstration will help students understand the relationship between density and buoyancy.
Floating Grape Buoyancy Demonstration
Materials
- 2 drinking glasses (preferably identical)
- hot water from the faucet
- sugar
- spoon
- grapes
Procedure
- Add one cup of hot tap water to each cup.
- Add 2 tablespoons sugar to one of the cups.
- Stir the sugar with a spoon until dissolved. (If you can’t get it to dissolve completely, that is OK.)
- Place one grape in each glass of water.
Discussion
The grape in the sugar water should float while the grape in the plain water should sink. Which cup of water has a higher density? What can you infer about the relationship between density and buoyancy?
Follow up
Pour half of the sugar water into a third cup. Gently top it off with the plain water, trying not to mix the two. Now add a grape. You should see the grape float in the middle. Why?
This article is part of the Density and Buoyancy series. See the list below for links to the other articles in this series.
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