The Dead Sea Vs. Fresh Water

Daniel Maldonado Sanchez

Throughout my life, I always wondered why I floated much better in the beach than the pool. Since I always was fascinated with documentaries on bodies of water such as the Dead Sea and the Great Salt Lake, I decided that something in these bodies had something unique that allowed great buoyancy. Because of my interest in this question, I turned to the concept of buoyancy. Buoyancy is nothing other than “the tendency of a body to float or to rise when submerged in a fluid.” But in order for this to happen, the fluid has to exert an upward force on the body in order to maintain the body above the surface of the body. 

From common sense, I knew that the salt had something to do with this phenomenon, but that was all I knew before I understood that physics principles apply in order for this to take place. The principle that significantly applies to this is Archimedes’ Principle, which states “if the weight of the water displaced is less than the weight of the object, the object will sink, otherwise the object will float, with the weight of the water displaced equal to the weight of the object.” So if the displaced water weighs less than an object that is trying to float, then it will sink. But if the displaced water is equal to the object trying to float, then the object will indeed float. This cleared many doubts in my mind, because when I spread my body as uniformly as possible, I tended to float evenly, compared to when I stood up in the water.

The salt that I knew that had something to do with this absolutely did, as “the Dead Sea has a density of 1.24 kg/L, making swimming difficult, but providing a relaxing floating experience.” And because “the density of fresh water is 1.0kg/L and that of a human body is of 950g/L, therefore an individual can float with ease over the water.” If we put the numbers into perspective, then one can conclude that if one has the capacity to float with not much trouble in fresh water of 1kg/L, then it will be way easier to float on denser saltier water of 1.24kg/L.  I finally understood that the beach water was denser than the pool water from which I swam regularly, as a result of all the salts and minerals the beach has in its recipe.

Floating is summed up in a couple of concepts and principles; density, buoyancy, and the principle formed by Archimedes himself. Understanding these concepts and principles, will guide one into realizing that floating has many interesting physics principles applied, if one tries to question why one is floating in the first place. Once one floats, the upward pressure on the body on the water is equal to the weight of the fluid displaced by the object. Displace the weight of an object and the object floats, making the person enjoy his or her time in the body of water when trying to perform this motion.

References:

"Archimedes' Principle." Physics. Web. 28 Apr. 2011. .

"Buoyancy - Definition and More from the Free Merriam-Webster Dictionary." Dictionary and Thesaurus - Merriam-Webster Online. Web. 28 Apr. 2011. .

"Dead Sea." Wikipedia, the Free Encyclopedia. Web. 28 Apr. 2011. .

Hernandez, Antonio J. "LA FLOTACIÓN." Enseñanza / Metodología. I-natacion.com. Web. 28 Apr. 2011. .