CK-12-Physics - Intermediate

http://www.ck12.org Chapter 12. Fluid Mechanics

FIGURE 12.1

Density and Specific Gravity

Measured in these grams per cubic centimeter, density is the same asspecific gravity, defined as the ratio of the
object’s density to the density of water. The density of water (at 4. 0 ◦C) is

ρwater=

1 .00 g

cm^3

=

1000 .0 kg

m^3

So, the specific gravity of water is 1.00, and the specific gravity of aluminum is 2.7. There are no units for specific
gravity, because it is defined as the ratio of one density to another.

Illustrative Example 1

a. A United States 25-cent coin (a quarter) is composed of copper sandwiched between two coatings of nickel,
Figure12.2.

The copper in a quarter occupies a volume of 5.84 cm^3 and has a mass of 5.198 g. What is the density of copper?

Answer:

ρcopper=

m

V

=

5 .198 g

0 .584 cm^3

= 8 .90g/cm^3

.

b. What is the specific gravity of copper?

Answer: