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DENSITY VS BUOYANCY

Let's find out if the density of water makes a change in buoyancy.

We can put an egg in a glass of plain water. What does it do? Now watch, and see what happens when we fill another glass with water, and add 1 or 2 tablespoons of salt. Stir it, so it dissolves. Put an egg into this mixture, and see what happens.

Now, let's decide why the egg floats better in the salt water. The water is made more dense by the addition of salt. There isn't as much difference between the density of the salt water and the egg as there is between the plain water and the egg. I once read that when people goe swimming in the Great Salt Lake in Utah, they don't have to work very hard to stay afloat. I guess it is the same with the egg.

Let's increase the density of the water in a different way. We can very carefully open and empty two tea bags, being careful to keep the string on the bags, then fill them with salt. We'll put warm water into a beaker, and drop a few peanuts into it.

Of course, the peanuts have to have their shells, or it won't work. We have to remember, also, that as with almost every- thing that grows, there are little differences, and all peanuts are not alike. Some will have bigger nuts inside their shells. Probably the shells with bigger nuts will sink.

Hang the two tea bags on opposite sides of the container and watch what happens. Let's put some black paper behind the beaker so we can see better.

Is it getting stormy in there? It looks like a cloud forming at the bottom of the beaker. That probably means that the salt is dissolving. Chemists like to say it is "going into
solution." We already know that salt dissolved in water makes the water more dense, so the part of the water that has the cloud in it is more dense than the clearer water.

How do the peanuts like it? Are they having a good time? It's hard to tell--they don't have much to say. It looks as though the denser water has more buoyancy, and is pushing up on the peanuts.

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