If you have a homogenous substance, such as water, the mass of an amount
of the substance is proportional to its volume. The ratio of mass to
volume is then a constant, called the **density**. The density of an
object is therefore found by dividing the mass by the volume. In other
words,

In this assignment we will calculate the densities of various objects. Because our volume measuring devices use metric measurements, measure mass in grams.

**Problem 1**. Weigh 300 ml of water and use your measurement
to calculate the density of water. Weigh two other volumes of water and
repeat the calculation of the density of water.

**Problem 2**. Find the weight and volume of two rocks.
Calculate the density of each rock. Describe how you measured the
volume of the rocks.

**Problem 3**. Calculate the density of one of the following items: a
marble, a penny, or a nickel. Before you do this, think about how you
can measure the mass in a way that gives you as accurate a
measurement as possible with the tools you have. Describe how you
measured the volume of the object you used.

**Problem 4**. If you had a cubic meter of your first rock,
approximately what would be the mass of this amount of
rock? To find this, you can use the formula defining density to find
mass, since ** mass = density × volume**. You will also have to do
some unit conversions.