Volume
Everything takes up space. Volume
is the amount of space that an object occupies.
Liquids
occupy the shape of the container that they are in. This can be thought of as
occurring because of the atoms or molecules moving faster and being farther
apart than they are in the solid. Liquids and solids do not compress a great
deal, but gases do. Gas molecules
occupy the shape of any closed container that they occupy. Gas molecules move
faster and are farther apart than liquids and solids.
To compute the volume of any rectangular solid (ÒPrismÓ in
the image above.), simply multiply its length (h) by its width (a) by its depth
(b) [V =abh].
If an iron bar is
10. centimeters (cm) long, 4 cm wide, and 2 cm thick, its
volume then is 80 cm3 (10. cm x 4 cm x 2 cm = 80 cm3). The green cube has a side equal to two centimeters; what is
the volume of the cubic solid?
Unfortunately most solid
objects have irregular shapes. In such cases it is convenient to measure volume by the object's displacement of water. (Note: It must be completely submerged, not floatingÉ and
free of air to be accurate.) To do so, first accurately measure a volume of
water in a graduated cylinder, which is one
of many different types of containers used to measure the volume of liquids.
Then carefully place the solid object
in the cylinder. The water rises, indicating that the combined volume of
the water and the solid is greater than the volume of the water alone. The increase in volume represents the
actual volume of the irregular solid
object. For example:
An irregularly shaped piece of green jade was
found near the Great Wall of China. To determine
its volume by water displacement, a graduated cylinder was filled with 50.0 mL of water. The
jade was then added and its volume was determined to be 10.5 mL or 10.5 cm3 as seen in the image. (Generally 1 ml equals 1 cm3.)
The volume of an object will vary with temperature and pressure.
