Floating and Sinking

The Rule of Floatation

Whether an object floats or sinks depends (mostly) on its density relative to the fluid.

• Float: If Object Density < Fluid Density.
• Sink: If Object Density > Fluid Density.

Examples

1. Wood vs Iron: Wood floats on water ($<1 \text{ g/cm}^3$) while Iron sinks ($>1 \text{ g/cm}^3$).
2. Oil on Water: Oil floats because it is less dense than water.
3. Ice on Water: Ice floats because water expands when it freezes, making ice less dense than liquid water. This is crucial for aquatic life in winter!

The Egg Experiment

• Fresh Water: An egg sinks (Egg is denser than tap water).
• Salt Water: If you dissolve lots of salt, the water becomes denser. Eventually, the Salt Water is denser than the egg, and the egg floats!