Density is a measure of how tightlypacked 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, cm^{3}). The
units of density are thus grams per cubic centimeter,
gm/cm^{3}
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)R^{3}
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/cm^{3} (by definition), of rock around 3
gm/cm^{3}, and of iron around 10
gm/cm^{3}.
Sample Calculations
To see some sample calculations with density, click on
the examples below:
