The document discusses density and its calculation. Density is defined as mass divided by volume, with units of grams per cubic centimeter (g/cm3). Volume can be measured directly for simple shapes using length x width x height, but for complex shapes it is equal to the volume of water displaced. Archimedes' principle of buoyancy established that the volume of an object is equal to the volume of fluid it displaces. Density can be used to identify whether an object will float or sink in water depending on if its density is less than, greater than, or equal to the density of water, which is 1g/cm3. Density is an intrinsic property that can be used to identify materials.

1. Lorraine – You Are
My…
DENSITY

2. Density is…
 In general – the amount
of stuff in a given
space.
 Think population
density

3. Oklahoma New York

5. Density
 For science… density is equal to the
mass of a thing divided by its volume.
 What are mass & volume again?
 Mass – amount of matter – measured in
grams (g)
 Volume – amount of space something
occupies – measured in cm3 or mL
 ρ=m/v the units for density are g/cm 3
 (or g/mL )

6. Volume
 For the easy objects
 (length)x(width)x(height)
 l x w x h ~ (cm)x (cm)x (cm)=cm3
 What about cylinders and cones?
 What can we do for the not so easy
objects????
 Here is a clue - displacement

7. Back to odd shapes…
 Archimedes?? Do you know him?
 Was in his bath tub one morning – he noticed
that as his body went in to the water – the
water rose out of the way. He realized that
the volume of H2O that rose was equal to the
volume of his body.
 Legend has it that he ran down the streets of
Greece stark naked yelling “Eureka”. –
meaning – OMG I’ve Got It.

8. Eureka…
 The volume of an object is equal to the
volume of H2O it displaces!
 The implications of this discovery were
huge.
 It was later decided that 1g H2O = 1mL
H2O = 1 cm3 H2O
 So - what is the density of water???

9. So…
 If an object has a density <1g/cm3,
what will it do if placed in water?
 If an object has a density >1g/cm3,
what will it do if placed in water?
 If an object has a density =1g/cm3,
what will it do if placed in water?

10. Intrinsic properties
 Intrinsic properties are properties that
can be used to positively identify an
object
 Like fingerprints, dental records or DNA for human
ID
 Density is an intrinsic property – if you
know the density of a metal you can
use that to help ID the metal.