1.) Fill the cup about halfway with alcohol.
2.) Add several drops of olive oil to the alcohol. They will form distinct little spheres and sink to the bottom.
3.) Add water drop by drop until the balls of olive oil rise and become suspended in the middle of the water-alcohol solution.
The olive oil initially sinks because it is denser than the alcohol. However, it is less dense than water. By adding water to the alcohol, the density of the alcohol-water solution is gradually increased, until it becomes equal to that of the olive oil. At this point, the olive oil will neither sink nor float, but will become suspended in a state of neutral buoyancy. The density of the olive oil is now equal to that of the surrounding solution. Fish, submarines, and the Goodyear blimp can all experience neutral Buoyancy if their density is equal to that of their surroundings.
The olive oil is interesting to observe because it forms many tiny little spheres when it it added to the water. The oil does not mix with water due to oil’s non polar nature. Water molecules are polar, meaning they contain both a positive and negative end. A non-polar substance, such as oil, is completely neutral, so it does not readily mix with a polar substance. This property of the oil makes it easy to observe wet neutral buoyancy has been achieved.