Density describes how much mass is contained in a given volume. It is useful for identifying materials, checking measurements, and converting between related quantities.
The formula
Density equals mass divided by volume. Rearranging gives mass = density times volume and volume = mass divided by density. The units must be compatible before dividing.
Keep units consistent
A mass in grams and volume in cubic centimeters produces grams per cubic centimeter. If the volume is in liters or the mass in kilograms, convert first or clearly retain the combined unit.
Interpret the result
A higher density means more mass in the same volume. Temperature, pressure, porosity, impurities, and measurement error can make an observed value differ from a reference value.
A worked example
Worked example: a 200-gram sample occupying 50 cubic centimeters has a density of 4 g/cm3. If the same mass occupies more volume, its density is lower.
Record temperature and pressure when comparing with a reference table. Porosity, trapped air, and an uneven volume measurement can change the observed value.
Use a displacement method for an irregular solid when its dimensions are hard to measure. Avoid bubbles and read the scale at eye level because small volume errors can noticeably change density.
Report the unit with the number because 4 g/cm3 and 4 kg/m3 differ by a large factor despite looking similar.
Density calculations are simple, but unit consistency and real material conditions determine whether the answer is useful.
COMMON QUESTIONS
Frequently asked questions
Can density be negative?
For ordinary physical mass and volume, no. A negative result usually indicates an input or sign error.
Does density change with temperature?
Often yes, because volume can change. State the conditions when precision matters.