Materials:
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- Three ping-pong balls
- Two or three metal balls about the same size as the ping pong balls
- A bag of pinto beans
- A large mixing bowl
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| Directions: |
- Pour the beans into the bowl.
- Bury the ping-pong balls under the beans and lay the metal balls on top.
- Gently shake the bowl.
- The metal balls will sink to the bottom and the ping-pong balls will rise to the top.
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| Safety Concerns: |
- None
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| Questions: |
- What happened to the metal balls?
- What happened to the ping-pong balls?
- Compare the densities of the three objects.
- What would happen if we tried a similar experiment in water by dropping the metal balls
from the top and and releasing the ping-pong balls from the bottom?
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| Concepts: |
- The two types of balls and the beans all have different densities. The metal balls have
the highest density, the ping-pong balls have the lowest density, and the pinto beans have
a density somewhere in between. When you first start shaking the bowl, all the objects are
free to move around. The metal balls are the densest so they sink to the bottom and the
ping-pong balls are the lightest, so they "float" up. The same effect happens in
water since water has a density somewhere in the middle between the metal balls and the
ping-pong balls.
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