DENSITYDENSITY

WHAT IS DENSITY?WHAT IS DENSITY?

Density is defined as the mass per unit Density is defined as the mass per unit volume.volume.

In other words, its how much matter is In other words, its how much matter is stuffed into a certain amount of space.stuffed into a certain amount of space.

For example, take a golf ball and a ping For example, take a golf ball and a ping pong ball. They are both about the same pong ball. They are both about the same size. Which means that they take up the size. Which means that they take up the same amount of space or have the same same amount of space or have the same volume. However, the golf ball has more volume. However, the golf ball has more stuff in it, therefore, it is more dense than stuff in it, therefore, it is more dense than the ping pong ball.the ping pong ball.

The FormulaThe Formula

The formula for calculating density is The formula for calculating density is D=m/VD=m/V

The “D” stands for Density (of course).The “D” stands for Density (of course). The “m” stands for mass which is measured The “m” stands for mass which is measured

in grams (g).in grams (g). The “V” stands for volume which is The “V” stands for volume which is

measured in cubic centimeters (cmmeasured in cubic centimeters (cm33) or ) or milliliters (mL).milliliters (mL).

The “/” means divided by.The “/” means divided by. Therefore, Density equals mass divided by Therefore, Density equals mass divided by

volume and its volume and its units are g/cmunits are g/cm33..

Check it Out!Check it Out!

On the front table, you see a plastic bin On the front table, you see a plastic bin filled with water.filled with water.

Water has a density of 1 g/cmWater has a density of 1 g/cm33.. For something to float in water, it has For something to float in water, it has

to have a density less than that of to have a density less than that of water.water.

When something sinks in water, it has a When something sinks in water, it has a density that is greater than water.density that is greater than water.

On your paper, predict whether the On your paper, predict whether the objects will sink or float.objects will sink or float.

PredictPredict

Now, let’s CHECK IT OUT!Now, let’s CHECK IT OUT!

NOW….NOW….

Will COKE or DIET COKE float in Will COKE or DIET COKE float in water? water?

In the Venn Diagram on your paper, In the Venn Diagram on your paper, list the similarities and differences list the similarities and differences between Coke and Diet Coke.between Coke and Diet Coke.

VS

DifferentMain ideas Similar Different

COKE

DIET COKE

•Shape

•Size

•Color

•Weight

•Ingredients

•Other

•are made by the same company •have the same shape •made of aluminum •are sealed shut •have the same amount of liquid - 12 fl oz •contain water •contain carbon dioxide •both have caffeine

•Red can•Regular (not diet)

•Contains sugar

•Contains nutra sweet

•Silver can•Diet soda

So….So….

Will COKE or DIET COKE float in Will COKE or DIET COKE float in water? water?

Let’s check it out.Let’s check it out. The Coke sank and the Diet Coke The Coke sank and the Diet Coke

floated. floated. WHY?WHY?

Because….Because….

Coke contains about 39g of sugar.Coke contains about 39g of sugar. Diet Coke contains about 0.1g of Diet Coke contains about 0.1g of

aspertame (NutraSweet).aspertame (NutraSweet). Therefore, Coke is more dense than Therefore, Coke is more dense than

Diet Coke and more dense than Diet Coke and more dense than water, so it sinks and Diet Coke water, so it sinks and Diet Coke doesn’t.doesn’t.

Practice Calculating Practice Calculating DensityDensity

Using the formula for density, Using the formula for density, D=m/V, calculate the density of an D=m/V, calculate the density of an object that has a mass of 35 g and a object that has a mass of 35 g and a volume of 7 cmvolume of 7 cm33..

Will this object float in water or Will this object float in water or sink?sink?

The EndThe End

Turn your papers in as you leave.Turn your papers in as you leave. Make sure that your name is on your Make sure that your name is on your

paper.paper. Have a nice day!Have a nice day!

Leigh Miller, Pillans MSLeigh Miller, Pillans MS