Have you ever tried floating on your back in the ocean, a lake, a pool, or even in your bathtub? You may have noticed that when you take a deep breath you float up a few inches, and when you breath out, you sink down. What makes something sink or float? Why would seaweed float on the top of the water, lobsters sink to the bottom, and jellyfish float somewhere in between? Conduct your own Sink or Float Experiment with some of the materials in and around your house to see what you can discover.
Neutral buoyancy occurs when an object’s density is the same as the density of the water (or other liquid). Many bony fishes have an organ called a swim bladder, which is filled with gas, that helps them to remain buoyant so they don’t sink to the bottom of the ocean. SCUBA divers are also trained in order to maintain neutral buoyancy using breathing and measuring devices. To learn more about neutral buoyancy, visit Sciencing’s Types of Buoyancy page.
Time for a challenge! Can you create an object that is neutrally buoyant using things you can find around your house? Try out our Neutral Buoyancy Challenge, and let us know what you find! Send a picture of your neutrally buoyant object to email@example.com and we will post it on our social media.