Pushing Water Around

Buoyancy

Things You Will Need
• Small ball of modeling clay (golf ball size)
• Large ball of modeling clay (orange size)
• Large bowl or bucket of water
• Marker or masking tape
• Paper towels

Do This

1. Fill the bowl or bucket one-half full of water.
2. Mark the level of the water with the marker or masking tape.
3. Place the small ball of modeling clay into the container of water.
4. Mark the new level of water with the marker or masking tape.
5. Remove the small ball of modeling clay.
6. Place the large ball of modeling clay into the container of water.
7. Again mark the level of water.
8. Remove the large ball of modeling clay and blot it dry with the paper towels.
9. Mold the large ball of modeling clay into the shape of a flat-bottomed bowl or boat.
10. Place the clay bowl or boat on the water surface.


What Should Have Happened

The amount of water that an object pushes out of the way or "displaces" depends partly on its size and partly on its shape. Large objects displace more water than smaller objects of the same shape. The small ball of clay should not have raised or "displaced" as much water as the large ball of clay. The flat-bottomed bowl or boat should have raised or "displaced" the most water. This shape had both the clay and the air inside the shape pushing the water out of the way, whereas the solid large ball only had the clay pushing the water.