Density

An important property of any material is its density, defined as its mass per unit volume. A homogeneous material such as ice or iron has the same density throughout. We use (the Greek letter rho) for density. If a mass m of homogeneous material has volume V, the density is

Two objects made of the same material have the same density even though they may have different masses and different volumes. That’s because the ratio of mass to volume is the same for both objects. 

The SI unit of density is the kilogram per cubic meter . The cgs unit, the gram per cubic centimeter is also widely used:

Densities of Some Common Substances