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 )
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
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.
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???
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?
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.