Units of Measure
Section 1.4 Metric Volume and Density
Pre-View 1.4
• Volume – the amount of space an object
occupies
• Cubic meter – the amount of volume in a
box that is one meter long, one meter
wide, and one meter high
• Liter – common metric unit used to
measure liquid or gas volume
• Milliliter – the volume equal to one cubic
centimeter (cm3)
Pre-View 1.4
• Water displacement – a method used to
find the volume of an irregularly shaped
object.
• Graduated cylinder – piece of equipment
that can be used to find the volume of an
irregularly shaped object.
• Density – the measure of mass per unit of
volume; calculated by dividing mass by
volume.
Measuring Volume
• Volume is a measurement of three
dimensions and is calculated by
multiplying length, width, and height.
– For example, the volume of one cubic
meter (m3) can be represented by a box
that is one meter long, one meter wide,
and one meter high.
Measuring Volume
• Instead of using cubic units like m3 or cm3,
volume can also be expressed in liters (L).
• One cubic centimeter is equal to one
milliliter (mL).
• Solid volume is usually given in cubic
meters or cubic centimeters, but gas and
liquid volumes are commonly given in
liters or milliliters.
Measuring Volume – Regularly Shaped Objects
• Regularly shaped objects are objects that
are square, rectangular, cylindrical, coneshaped, or spherical.
• By using a ruler to determine one or more
of their dimensions, you can then use a
formula to determine volume
– Example – to determine the volume of a
rectangular object, measure each
dimension. Then multiply the three
dimensions together.
Measuring Volume – Regularly Shaped Objects
For Example:
Using a ruler, John determines his biology
textbook is 25 centimeters wide, 30
centimeters long, and 3 centimeters thick.
What is the volume of the textbook:
25 cm x 30 cm x 3 cm = 2250 cm3
The textbook’s volume is 2,250 cm3
Measuring Volume – Irregularly Shaped
Objects
• Many objects are not perfectly rectangular.
• Water displacement can be used to obtain the
volume of an irregularly shaped object.
– First, a known volume of water is recorded.
– Then the object is submerged in the water,
and a water plus object volume is determined.
– The difference in the first volume and the
second volume is the volume of the object.
Measuring Volume – Irregularly Shaped
Objects
Example
• Dr. Watts, a paleontologist, wants to know the
volume of a fossilized bone.
• She measures exactly 10 mL of water in a
graduated cylinder.
• She then drops the bone into the graduated
cylinder.
• The volume of the water and the bone measures
12.5 mL. What is the volume of the bone?
Measuring Volume – Irregularly Shaped
Objects
Example (continued)
12.5 mL – 10 mL = 2.5 mL
The bone has a volume of 2.5 mL, which is the
same as 2.5 cm3.
SI unit of Volume: cubic meter (m3)
• When to use it…
– Use cubic meters for large volumes.
• Example:
– The water volume in an Olympic
swimming pool is about 2500 m3
SI unit of Volume: liter (l)
• When to use it…
– Use instead of quarts or gallons.
• Example:
– A common size for a large soft drink
container is 2 liters
SI unit of Volume:
cubic centimeter (cm3) or milliliter (ml)
• When to use it…
– Use cubic centimeters or milliliters for
small solid or liquid volumes.
• Example:
– A small cellular phone is about 90 cm3
– A 20 ounce soft drink bottle holds about
590 ml
Measuring Density
• Density is mass per unit of volume and is
a common value measure in science.
– To get an idea of what density is, think
about a marble and a small styrofoam
ball that are the same size and have the
same volume.
– The marble will sink in water, but the
styrofoam ball will float.
Measuring Density
– If they are the same volume, why does
one sink and the other float?
• The answer is density.
• The marble is dense and has more
mass in the same amount of volume
than the styrofoam.
• In general, an object that has a density
greater than the density of water will sink
in water.
Measuring Density
• An object having a density less than the
density of water will float.
• Water has a density of one gram per
milliliter (1 g/mL)
To determine density of an object, you
divide the mass of the object by the
volume of the object. The resulting units
are commonly g/cm3, kg/m3, g/mLor kg/L
Measuring Density
Example
• In the previous example, Dr. Watts found
the volume of a fossilized bone to be 2.5
mL. She determined that the mass of the
bone is 9 grams. What is the density? Will
it float or sink in water?