Final answer:
Density is the mass of a substance divided by its volume and is key in determining an object's buoyancy. It varies between states of matter, with solids and liquids typically being denser than gases.
Step-by-step explanation:
Density is a physical characteristic of matter, defined as the mass per unit volume of a substance. It is represented by the equation ρ = m/V, where ρ (rho) is the density, m is the mass, and V is the volume. Density is crucial for determining whether an object will sink or float in a fluid. Atoms and molecules in solids and liquids are closely packed, resulting in higher densities compared to gases, where they are separated by empty spaces. For example, if the distance between atoms in a solid increases, leading to an increase in volume, the density would decrease significantly, demonstrating the inverse relationship between volume and density.
Density is a physical characteristic of matter.
Atoms and molecules are close together in solids and liquids, while in gases they are separated by empty space.
Thus, a substance made of tiny particles closely packed has a higher density than something filled with air (keeping volume the same for both).