what is density ?

Density is a measurement of how solid something is. Specifically it is the mass per unit volume of a substance. If you have two objects of the exact same size (volume), the more dense object will weigh more than the less dense object. So there are two things contributing to density: 1.The mass of the atoms or molecules that makes up the material. 2.The volume or amount of space the material takes up. If the molecules or atoms are “packed” in more closely, it will be more dense. For example, styrofoam is a low density material. Even a large styrofoam container does not weigh much. The molecules in the styrofoam do not have much mass and there is a lot of space between them. A brick, on the other hand, is much more dense. Even a moderate sized brick can be pretty heavy. This is because the molecules which make up the rock have more mass and are packed more closely together. Density and buoyancy are closely related. A less dense substance will float on a more dense substance. The density of a material varies with temperature and pressure. This variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance (with a few exceptions) decreases its density by increasing its volume. In most materials, heating the bottom of a fluid results in convection of the heat from the bottom to the top, due to the decrease in the density of the heated fluid. This causes it to rise relative to more dense unheated material. The reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density; rather it increases its mass. I think this is too much of info for this class category.Hope it clarifies read less