Finding Density All objects have mass. Mass is the amount of material in an object, usually measured by its
weight. Earlier in this unit, you studied the volume of objects. When you combine these two
concepts, you get a useful measurement called density. The density of an object is its mass
per unit of volume. Imagine two objects in which the larger one actually weighs less than the
smaller one. This difference in weight is attributed to density.
Consider a candle that has a volume of 96 cubic inches and a weight of 44.16 ounces. What
is the density of the candle? The density is defined as its mass per unit volume, so simply
divide the mass of the candle by its volume:
44.16 ounces
volume
96 cubic inches = 0.46 ounces/cubic inch.
In this case, you are finding the average density of the candle. In most cases, you will be
finding the average density of objects because most objects do not have a uniform density.
For instance, the portion of the candle where the wick is might have a different density than
the rest of the candle.
Now that you know about density, let's work on some applications.
Harold is a woodworker and is interested in finding the density of two different types of
wood. He bought a pine log that has a 5-inch radius and is 30 inches long. The weight of the
log is approximately 42.63 pounds. He also has an oak board that is 5.5 inches wide, 1.5
inches thick and 3 feet long. The board weighs approximately 8.05 pounds.
density = mass
What is the density of the pine log