Density is a measure of how tightly-packed material is within an object. It is computed using the formula 

Density = M / V 

where M is the mass of the object (the amount of material in the object, usually measured in grams, gm) and V is the volume of the object (the amount of space it takes up, usually measured in cubic centimeters, cm3). The units of density are thus grams per cubic centimeter, gm/cm3

Most of the objects we will be considering will be spheres (or nearly so), so their volumes can be computed using the formula for the volume of a sphere:

V = (4/3)(pi)R3

where R is the radius of the sphere (in cm) and (pi) is equal to 3.14.

For reference, the density of pure water is 1 gm/cm3 (by definition), of rock around 3 gm/cm3, and of iron around 10 gm/cm3.

Sample Calculations

To see some sample calculations with density, click on the examples below:



Updated 7/7/06
By James E. Heath
Copyright 2006 Austin Community College