Problem: What happens to an eye dropper, partly filled with water, when you place it in a full water bottle and the bottle is squeezed?
Procedure: Fill a cup with water. Place Squidy in the cup and squeeze to fill with water so it is barely floating. Fill the big bottle with water. Drop Squidy in the bottle. Squeeze the middle of the bottle, really strong. OBSERVE.
Materials: eye dropper (Squidy), water bottle, cup, water
(a) The top of the bottle will shoot off. (6)
(b) Squidy will sink. (0)
(c) Squidy will swim up and down, up and down. (1)
(d) Squidy will float, no matter what you do. (8)
Conclusion: When you squeeze the bottle, Squidy fills with water and becomes heavy. Heavy things sink. When you let go of the bottle, Squidy loses water and becomes light. Light things float. Below, you can see "naked Squidy" to see what's happening inside the eye dropper.
For Fun: You can buy your own Squidy if you want to try this at home. You can also make a "naked Squidy" very easily out of an eyedropper and hex nut.