Discovering Density Density Density describes how much space an object or substance takes up Density represents how thick or closely packed together an object of substance is Density can vary depending on temperature and pressure Density is the mass of an object or substance divided by its volume Mass Mass is the amount of matter taken up by an object Although mass is often referred to as weight and weighed in kilograms, they are not the same thing An object’s weight will vary according to gravity; its mass will not change Volume Volume describes the amount of space taken up by an object or substance Liquid Density Liquids are made up of tiny particles The density of a liquid depends on how tightly packed together these particles are Different liquids have different liquid densities Water has a density of 997 kg/m³ Some liquids have a higher density than water These liquids will sink below the water, leaving the water to float above Other liquids have a lower density than water These liquids will float above the water