CARTESIAN DIVER

PROBLEM: When you squeeze the sides of the bottle, why does the diver fall?

RESEARCH: Read about a man named Archimedes, who lived in ancient Greece. Find out what he discovered when he was in the bath. What does displacement mean?

HYPOTHESIS: What do you think happens to the weight of the diver when you squeeze the sides of the bottle?

MATERIALS:          2 liter bottle with cap

          1 eyedropper

          water          

PROCEDURE:

1. Fill the bottle full of water.

2. Fill the eyedropper about 2/3 full of water.

3. Put the dropper into the bottle and screw on the cap. Be sure the diver floats before putting on the cap.

4. Squeeze the sides of the bottle. Release the sides and observe what happens.

5. Record your observations in your data table.

DATA: Make a data table to record your observations and inferences.

CONCLUSION: This is not optional. You must explain what you learned by doing this activity.

Remember that you must answer the question you asked in your original problem statement.

NOTE: BE SURE TO HAVE YOUR PARENT OR GUARDIAN SIGNS YOUR WORK. PARENTS: YOUR SIGNATURE SHOWS YOUR STUDENT HAS DONE THE WORK.

Here is a secret to help you see what you are supposed to see. Watch what happens to the air bubble in the dropper. Try to explain what you see.

TEACHER SECTION:

POSSIBLE HYPOTHESIS: The diver will fall when the sides of the bottle are squeezed because the squeezing pushes it down.

POSSIBLE CONCLUSION: The diver falls because the air is compressed into a smaller space and becomes denser, weighs more. The bubble in the dropper got smaller. The diver comes back up because the air expands and is less dense.

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Judy Schneider

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