Mass: Mass is the amount of matter in an object. It is measured in kilograms (kg). The mass of an object does not change when it is compressed. This is because the number of atoms in the object does not change when it is compressed.
Volume: Volume is the amount of space that an object occupies. It is measured in cubic meters (m^3). When you compress a piece of Styrofoam, its volume decreases. This is because the molecules of Styrofoam are forced closer together when it is compressed.
Density: Density is the mass of an object per unit volume. It is measured in kilograms per cubic meter (kg/m^3). When you compress a piece of Styrofoam, its density increases. This is because the mass of the Styrofoam remains the same, but its volume decreases.
