Density
Density
Density= Mass
Volume
D=
m
V
Mass
•  Mass: Amount of matter in a substance.
•  Units: Grams (g) Kilograms (kg)
•  Don’t confuse with weight.
Weight: the force with which the earth pulls
on the substance (Gravity).
Volume
•  Volume is the amount of space an object
takes up
•  Units for volume: ml Milliliters L liters
centimeters cubed cm3
Volume of a regular solid
Length (L) x Width (W) xHeight (H)=units3
Calculating volume of irregular
objects
•  Use a graduated cylinder For water
displacement
•  Add water to a predetermined level record.
•  Gently drop in the irregularly shaped
object.
•  Read the graduated cylinder – record.
•  Subtract the first water level from the
second – this is the volume
Question
Which weighs more?
50 kilograms of iron
Or
50 kilograms of feathers
Question
Which has a greater
density?
iron
Or
feathers
Common Units of Density
Density= Mass
(g)
Volume (ml or cm3)
g/mL = g/cm3
1 mL=1 cm3
kg/m3
Densities of Common Substances
Density of Water
•  At 4oC water has its maximum density of
1g/cm3
•  -Ice is less dense than water so it floats on
the top of water
Density of Water and ICE
Density is a constant
•  Density is an intrinsic physical property.
-Never Changes for a substance
-Does not depend on amount of matter
(mass) you have
Will It float
•  If an object is less dense than the fluid it is
in it will sink
•  If object is equally dense it will Suspend
•  If object is more dense it will sink
Note (fluid/Liquid does not have to be water)
Calculating Density
Using the triangle
1.Cover up what you are trying to find
2. If the other letters are next to each other
you multiply them
3. If one is above the other than you divide
the top by the bottom