BAKERSFIELD, Calif. (KERO) — In this edition of Science Sunday, we’re going to do a simple experiment that demonstrates buoyancy, or whether something floats. Buoyancy is driven by density. Specifically, if something is less dense than the fluid it’s placed in, it floats! If it’s denser, it sinks.
Items needed:- One glass of water
- One raw egg
- One spoon
Step One: Fill a glass with water, and place an egg into the water. You’ll see the egg sink to the bottom.
Step Two: Add a spoonful of salt into the water, and stir gently until it dissolves (don’t crack the egg!). You likely won’t see much change in this step.
Step Three: Continue to add spoonfuls of salt and continue to stir until the salt dissolves. Once you’ve added enough salt to the water, the egg will float up to the top!
How it works: As we said before, objects float when they are less dense than the fluid surrounding them.
The formula for density is: Mass is the amount of matter, or stuff, in an object. Volume is the amount of space that stuff takes up. When we add salt to the water, we’re adding more stuff, so the mass increases. However, the salt is dissolved in the water, so the volume changes very little. That means the density of the water goes up when we add salt. As we add more and more salt the water becomes more and more dense, and eventually becomes denser than the egg. When that happens, the egg floats!