Boat with Ballast: Testing Experiment

Aim

Good prediction experiment where students can test whether their newly formed rule about buoyant forces really works.

Prior Knowledge

• Establishment of Archimedes Prinicple: What does the buoyant force depend on?
• Conservation of fluid.

Description of the Experiment

A "boat" carrying some heavy ballast (which is denser than water) floats in a bath of water. The water level is carefully noted. The ballast is then taken out and dropped into the water. Predict what will happen to the water level in the bath.

This experiment is probably not going to be video taped in the forseeable future. However, this is a really easy experiment to try at home. First try and predict what will happen to the water level when the ballast is removed from the boat and placed in the water. Then try the experiment. To get a clear result, you will need a boat which can carry a lot of ballast. Also try and use a water container whose diameter is not much larger than the length of the boat.