Think about the last time you had a root beer float. That
sweet, creamy ice cream floating in ice cold root beer always satisfies.
Have you ever wondered why ice cream that is frozen solid can float in
a liquid? It might be difficult to see when they are not mixed, but the
ice cream has air trapped inside, so it is actually less dense than the
root beer. In the last unit you
learned that density is a measure of how closely the particles of matter
are packed together. Density affects more than just dessert treats, though.
Our entire Earth is structured around the densities of the materials
which make it up. One property of density is that it determines the way
materials in a mixture are sorted. This property of matter results in
the layering and structure of Earth's atmosphere, water, crust, and interior.
Scientists use models to describe the structure of Earth. Let’s
find out how!