Volume, Mass and Density
Volume: the amount of space that an object occupies
Mass: the amount of matter in an object; unlike weight, mass is NOT affected by location
Density: the concentration of matter in an object. Often given as a ratio of mass to volume
Density =
Formula found on
pg. _____ in the
ESRT
Mass
Volume
M
D
V
Volume: the volume of an object is found by multiplying all three dimensions of the object. For
example, the volume of a cube is found by multiplying the length, width and height.
The volume of this cube would be: a x a x a or a3
(Example A)
What is the volume of this cube if all sides are 3cm?
3cm x 3cm x 3cm = 27cm3  DON’T FORGET: cm to the third power!
(Example B)
What is the volume of this one if all sides are 1.5cm?
1.5cm x 1.5cm x 1.5cm = 3.375cm3
Volume units are always given in some distance cubed… (ft3 , m3 , cm3 )
*Volume units are always labeled in some distance cubed… (cm 3, ft3, m3) Most often
in this class we will use cm3.
Mass: How much matter… does it matter??
Mass is the amount of matter in a substance or object. If there are a lot of molecules of matter
OR if the molecules are very large molecules, there will be a high mass.
Instruments to measure density:
Density of a liquid: ____________________________
Density of a solid: ________________________ and ________________________
(Example C)
In the diagram to the left, the
mass of object x=80 grams.
The volume can be determined
by the change in the fluid level.
What is the density of object X?
_______________
Mass = 80 grams
Fluid level changes from 40 to 65 cm3,
so volume = 65-40… which = 25 cm3
Density = 80 g / 25 cm3 = 3.2 g/cm3
Total Mass = 6 g
Total Mass = 24 g
Total Volume = 1 cm3
Total volume = 4 cm3
Density = 6 g/cm3
Density = 6 g/cm3
What is the relationship between size and density??
As size increases or decreases, DENSITY REMAINS THE SAME!
As a rule, things that are MORE dense will sink or fall to the bottom of things that are LESS
dense (think of oil and water). My friend is a comic book freak. He thinks he wants to fly like
superman, but in order to do that, he would have to have a density LESS than air.
What are two things that he could do to decrease his density? THINK ABOUT IT!
(Hint – look at the density equation. Play with some numbers.)
Notice that if you DECREASE the mass of something or INCREASE the volume, the
density will be less…
D=M/V
D = 3g / 6cm3
D = 6g / 6cm3
D = 1g/cm3
D = 0.5
If we DECREASE the mass…
Or if we INCREASE the volume…
g/cm3
D = 6g / 12cm3
D = 0.5
g/cm3
*** If you cut a piece of anything in half, you cut the mass and the volume in half as
well, so a certain material ALWAYS HAS THE SAME DENSITY.
THE DENSITY OF ANY MATERIAL NEVER CHANGES