# Density Notes - Mrs. Pefanis' earth science home Density Notes A I M : H OW I S A N O B J EC T S DE N S I T Y D ET ER M I N ED? Why does this happen? Watch the following video clip then answer the question above: http://youtu.be/aR0b4QRhfU0

What is Density? Which one is more dense, a bowling ball or a soccer ball? Even though they are both approximately the same size and shape, the bowling ball is much more dense. Density

It depends on the mass of particles and how closely packed they are. Formula can be found on the 1st page of the ESRT Density: Mass

Volume Find the Density of the cube Mass = 480 grams 480 g =2

8 cm g/cm3 240 cm3 3 cm 10 cm

Density Triangle Volume Density Facts The Density of a substance remains the same regardless of size, shape, or mass of sample. Example: The density of a piece of aluminum

is 2.7g/cm3. If you cut the AL bar in half, what would be the density of each piece ? 2.7g/cm3 Density Facts Continued In what phase are most natural substances the densest?

Solid Phase (ex. Aluminum, lead, steel) However, there is one exception. Water! In what phase is water the most dense? And how do we know this? Liquid- Ice cubes (solid) float in a glass of water (liquid). Phases of Matter

Changing phases of matter animation Ice floats because it is less dense then the liquid. Only 10 % of Ice

floats above the water, while 90% floats below. One of the main reasons

why the Titanic sunk. Density Facts Continued Warm air rises because it is less dense, and cold air sinks because it is more dense.

Lets see Density in action Two Ways To Change Density 1. Temperature As temperature increases density decreases because molecules move further apart. Indirect Relationship 2. Pressure

As pressure increases density increases because molecules move closer together. Direct Relationship Car getting crushed