Density

Density is a measurement that compares the amount, ratio, of matter an object has to its volume. An object with a lot of matter in a certain amount of volume has high density. An object with a little matter in the same amount of volume has a low density.

Temperature has an effect on density. When the temperature of a substance increases,the density decreases. When the temperature of a substance of a substance decreases, the density increases. Many substances follow this rule, but there are exceptions. Water is one such exception. Fresh water is the only liquid with a density of 1.

The most common SI units for density are g/cm³ and kg/m³. When the numerator is much larger than the denominator, that means the substance has a higher density. When the denominator is much larger than the numerator, the substance has a lower density.

A formula to find out density is:

$density = mass / volume$

Sometimes scientists use the idea of density to talk about other properties instead of mass. They're trying to describe how much of a property can be found in a specific piece of what they are looking at. For example, population density is how many people live within the same amount of space. The population density in the city is higher than the country side because there are more people living closer to each other in the city. In computers, storage density is how much data can fit on disks in relation to their physical size. A blu-ray disc has a higher storage density than a DVD which has a higher storage density a CD, even though they all have almost exactly the same volume.