DensityDensity• DensityDensity is how much mass something

has in a certain volume

100kg

200kg

Which block has more matter in it?

The blue block must have a higher density!

How can one have more matter if they are the same

size?

The yellow block has more more mattermatter contained in the

same volumesame volume as the blue block. Therefore, the yellow matter must be yellow matter must be

more densemore dense.

Which block has higher density?How do you know?

Which block has higher density?

If it is the same type of matter, then it has the same densitysame density

because the matter is equally crowded.

The size of the piece does not

make a difference.

Which block is more dense?

The pink block is smaller, but it still has a higher density, because

the matter is more crowded.

You can use density to predict if You can use density to predict if an object will float or sink.an object will float or sink.

If something is more densemore dense

than the fluid, it will sinksink.

Will the yellow object float or sink?

If something is less denseless dense

than the fluid, it will floatfloat.

Will the brown block float or sink?

The duck isless denseless dense than water

so it floats

The anchor ismore densemore dense than water

so it sinks

How can a balloon float just by filling it with hot air?

video

Inside balloon

Outside balloon

When a fluid gets hot, its density changes!

• The formula for calculating density is:

Density =Mass

Volume

How can you figure out the density of an object?

You need to measure the massmass and the volumevolume.

m

v d

DMV Triangle: Cover the variable that you need to find, the triangle will tell you what math to do to find it.

Remember how to measure mass?Remember how to measure mass?• Mass is a measurement of the amount amount

of matterof matter that something has.

• The SI unit for mass is the gramgram.

• Mass is measured with a balancebalance.

Balance

Remember how to measure volume?Remember how to measure volume?• Volume is the amount of space that amount of space that

something takes upsomething takes upVolume is measured differently for liquids and solids

Volume of LiquidsVolume of Liquids• The SI unit for liquid is literliter• Liquid volume is measured with a graduated graduated cylindercylinder

Rectangular Solids

Length

Hei

ght

Width

1.6cm x 1.3cm x4.1cm = 8.528 cm3

cm cm cmx x = cm3

8.5 cm3

Displacement method

Irregular Solids

65 mL 69 mL

Volume of Hammer? 4 mL or 4 cm3

Because the hammer is solid, we use cm3!

Calculating density is simple!Calculating density is simple!1. Measure the massmass.

2. Measure the volumevolume.

3. DivideDivide.

Mass (grams)

Volume (cm3)Density =

The units that we use for density are grams/cmgrams/cm33

Say “per”

Density ProblemsDensity Problems(Use the DMV triangle!)(Use the DMV triangle!)

1. If 52 grams of matter has a volume of 65 cm3, what is the density of the matter? Will it float or sink in water?

2. If a 32 gram piece of wood has a density of 4 g/cm3, what is the volume?

3. A metal washer has a mass of 27 g/cm3 and a volume of 3 cm3. What is its mass?

4. If an object has a mass of 810 g and a volume of 45 cm3, what is its density? Will it float or sink in water?

5. When you add a rock to 70 mL of water in a graduated cylinder, the water rises to 80 mL. The density of the rock is 4.2 g/cm3. What is the rock's mass?

6. What is the volume of a sample of liquid with a density of 20 g/cm3 and a mass of 25 g?

7. A 540g fish displaces 90 cm3 of water. What is the density of the fish?