DensityMaking sure we KNOW

what density is and how the density of air affects air

pressure.

What is the formula for density?

density = mass / volume

density = mass ÷ volume

density equals mass divided by volume

= ________per________

density (how crowded something is)

how much mass (stuff)

how much volume (space you fit it into)

Which is more dense? Why?

The box on the right is more dense, because there is more

mass (more molecules) crammed into the same

volume.

Which is more dense? Why?

The box on the left is more dense, because the same amount of mass (9 molecules of air) is crammed into a

smaller volume.

http://www.freeprintablecoloringpages.net/samples/Landscapes/Mountains_And_Palm_Tree.png

Density changes with altitude

More

Less

Air pressure decreases

when altitude

increases

http://www.goplayoutdoors.com/Member/arizonahotairballoonrides/images/three_hot_air_balloons_floating_hg_clr_26790.gif

Heat up the air inside a balloon and…The molecules gain energy. They move around more. They take up more space, so the volume increases.

Because the volume increases, density ________ decreases

Lower density means the balloon will RISE.

3 ways to increase the density of air inside a balloon

2. Squeeze the balloon so that it has less volume.

1. Cool the air so that the molecules have less energy, move less,

and therefore take up less volume.

3. Add more molecules so it has more mass.