Imagine a rectangular prism of pure water whose density (r) is 1.0 g/cm3 . The base of this imaginary prism is 1 cm on a side, and the remaining side of the prism is the water depth (a) measured in cm. The mass (m) of that prism of water, expressed in grams, is related to the water depth (a) in the following way: the value of a is the value of m.