What Is the Egg Flotation Hypothesis?

The egg flotation hypothesis is the prediction made by a student before investigating the buoyancy of an egg. The egg flotation experiment is a common project for young students, designed to educate them about the principles of buoyancy and water density. Typically, the student is presented with the question “will an egg float in water?” or “will an egg float in salt water?” before performing the experiment.

When placed in a glass of fresh water, an egg quickly sinks to the bottom. However, if salt is gradually added to the water, the egg eventually begins to float. This is because salt water has a higher density than freshwater does. Because the saltwater is denser that the egg is, the egg floats on top of it. If the salt was removed from the water or the solution was diluted by adding more fresh water, the egg would sink back down to the bottom.

This characteristic difference in the buoyancy of fresh water and salt water has important implications for boat designs; ships designed for freshwater use must be more buoyant than those that are designed for use in salt water. Engineers must also take buoyancy and solution density into account when designing objects that must float in fluids other than water.