Density

Sink or Float???

Definitions

• Measure of amount of matter in a given volume

• Simple definition: how much “stuff” is packed into a space

Float vs. Sink

• Objects LESS dense than liquid FLOAT• Objects MORE dense than liquid SINK

Formula

• Density is a measure of mass & volume• To calculate:

D = Mass/Volume

Or abbreviated

D = M/V

Units for Density

• Combine a unit of Mass, and a unit of Volume• Remember base units– Mass = Grams (g)– Volume = milliliters (mL) or centimeters (cm3)

• Why 2 units for volume?!?!– mL for fluids or irregular shaped objects– Cm3 for regular shaped objects

• So, unit for density is either g/mL or g/cm3

Relation to Earth Science

• Earth’s layers arranged due to density– Atmosphere (least dense)– Crust– Mantle– Core (most dense)

• Minerals & other pure substances (ex/water) can be identified by their unique density

• Ex/ gold = 19.3 g/cm3 ALWAYS!!!!!

Relationship btwn M, V & D

• If Mass decreases and volume stays same, then density decrease.

• If Mass increases and volume stays same, then density increases.

• If Volume increases and mass stays same, then density decreases

• If Volume decreases and mass stays same, then density increases