Why float in salt water

The salt concentration in the Dead Sea is parts per thousand, by contrast, ocean water is 35 parts per thousand. The high salinity means that swimmers float easily and a popular tourist activity is to recline effortlessly on top of the water while reading a newspaper or magazine. All you need is a peeled hard-boiled egg, a jar of warm water and salt.

Place the egg in the jar of water. It will sink to the bottom. Take the egg back out and stir in as much salt as will dissolve in the water. Try to place the egg in the jar again and this time, the salt has increased the density of the water enough to float the egg.

Based in Wenatchee, Wash. She has written peer-reviewed articles in the "Journal of Wildlife Management," policy documents,and educational materials. The Dead Sea is not really a sea at all, but rather a salt lake , bordered by Jordan and Israel. This high concentration of salt makes the water very dense. Life cannot survive in that concentration of salt—hence the name.

The human body, by comparison, is not as dense as the salt water. Therefore, humans float in the Dead Sea! This concept explains why floats sit on top of fresh water. Filled mostly with air, a water float is not dense enough to sink into fresh water. Our bodies become buoyant. The fresh and saltwater mix and a salinity is reached. The ocean is continuously in motion. A large part of this motion is driven by water with different temperatures and different concentrations of dissolved salts in different areas of the ocean.

In this article, we will discuss how these differences in ocean water can create ocean currents. We also tell you how to perform a simple experiment that can easily be done at home, to illustrate the formation of ocean currents. Although we are often taught to think of oceans like the Atlantic Ocean or the Pacific Ocean as separate from one another, in reality all ocean basins are connected together, forming one enormous ocean [ 1 ].

In this enormous ocean, which extends all around the world, water moves out of one basin and into another. On its journey around the globe, the water transports heat and salt from the tropics to the earth's poles, nutrients from the ocean's depths to the surface, and fresh water entering at the coast from rivers or melting glaciers out into the sea.

Even though the ocean is constantly in motion and there are lots of factors that affect how the ocean water moves, there is one natural phenomenon that has been contributing to ocean water movement for thousands of years: one large ocean current that connects all ocean basins, as well as the ocean surface and the deep ocean.

This current is sometimes called the global conveyor belt, for the way it circulates water all around the globe Figure 1. If water could be tracked on its journey on the global conveyor belt, following the red path as warm water nears the surface, then cools and sinks to follow the blue path until it comes back to the surface again, we would find that it takes the water around 1, years to complete its travel all the way around the world.

An obvious first guess as to what might cause this motion in the ocean is the wind. Wind blows over the ocean's surface, causing both waves and movement of water in a downwind direction. And indeed, parts of the global conveyor belt are driven by the wind [ 3 ].

Wind systems, like the trade winds for example, consist of strong winds that constantly act on large surface areas of the ocean, supplying large amounts of energy and putting huge volumes of water into motion. However, another part of the motion of ocean water in the global conveyor belt is caused by something much less obvious: density differences in the water. Density is a measure how heavy a certain amount of a substance is.

The definition of density is thus mass per unit volume. The ability of something, like the egg, to float in water or some other liquid is known as buoyancy. But just how much salt is needed to make an egg float?

In this science activity you'll figure that out by making solutions with varying concentrations of salt in them.

Observations and results Did the egg float in cup 1 and 2, but not in cups 3, 4 or 5? You likely saw that the egg floated best in cup 1, floated a little less in cup 2 but part of it was above the surface and did not float in the other cups.

Cup 1 had the undiluted salty solution that you originally prepared, which was one half cup of salt in two and one half cups water total. The concentrations of the salt solutions in cups 2 to 4 were halved as you increased in cup number; for example, the concentration of the salt in cup 2 was half that of cup 1, and the concentration of the salt in cup 3 was half again of cup 2.

Cup 5 had plain tap water. The egg should have sunk in cups 3, 4 and 5 because the density of the egg was higher than the density of the solutions or plain tap water in those cups.

Cups 1 and 2 had more salt in them than the other cups with cup 1 having the most salt , which means these solutions were denser. The egg should have floated with part of it above the water surface in these two cups because the solutions were denser than the egg.