Understanding
Density
What is Density?
• The ratio of the mass of a substance to its
volume
M
D=
V
– Volume – amount of space an object takes
up
– Mass – the amount of matter (stuff) in an
object
What is Density?
– Volume – amount of space an object takes up
– Mass – the amount of matter (stuff) in an object
– So density is the amount of stuff in a
certain space….
– The more stuff in a space  the
higher the density
• Which box has more stuff in it?
• Which box has the greatest density?
• Why does this box have the greatest
density?
•BECAUSE IT HAS
MORE STUFF IN IT!!!
Think about it…
• What is the most dense “phase” of matter?
– SOLID….why?
• Has the most “stuff” (matter) in the smallest space
• Huge Balloon versus Golf Ball. Which on
is more dense?
• Golf Ball …. Why?
• Has the most “stuff” (matter) in the smallest space
Heating an object…
Therefore: same “stuff” (matter) in
a bigger space = lower density
Expands- volume
increases = more
space
Matter – Stuff
inside remains the
same
Temperature & Density
volume
density
Temperature & Volume
temperature
temperature
Breaking up …
• If you break an object of uniform composition
in half, what happens to its density?
MASS = 100 g
VOLUME = 10 cm3
DENSITY = 10 g/ cm3
Breaking up …
• If you break an object of uniform composition
in half, what happens to its density?
MASS = 50 g
VOLUME = 5 cm3
DENSITY = 10 g/ cm3
MASS = 50 g
VOLUME = 5 cm3
DENSITY = 10 g/ cm3
WHY – MASS AND VOLUME CHANGE PROPORTIONALLY (EQUALLY)
Breaking up …
• If you break an object of uniform composition
in half, what happens to its density?
MASS = 50 g
VOLUME = 5 cm3
DENSITY = 10 g/ cm3
MASS = 25 g
VOLUME = 2.5 cm3
DENSITY = 10 g/ cm3