PURPOSE: To illustrate buoyancy in a perhaps counterinutuitive way.
DESCRIPTION: A heavy copper "boat" floats in a fish tank "pond," as seen in the photograph at the left. The water level in the pond is marked by the top of the black tape on either side of the tank. A cork is removed from a hole in the bottom of the boat, allowing the boat to fill with water and sink. Q: When the boat sinks, will the water level in the pond (a) go up, (b) go down, or (c) remain the same? A: As the boat sinks, the water level in the pond goes down, as seen in the photograph at the right.
SUGGESTIONS: See Question of the Week #98 for information on using this demonstration to enhance class involvement.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Fish tank with copper boat.
SETUP TIME: 10 minutes.