Density - Davis School District thinking about density ... Density = Mass Volume . To find density:...

Density

Go through the powerpoint and take notes on

the back of your Density Webquest.

Which do you think would have the

greater volume and mass?

Why?

1 kg of feathers

1 kg of rock

What the heck is density?

Density is a measure of the “compactness”

of particles

Density is how much matter is crammed

into a certain space.

Density is NOT the same as weight.

Here’s an analogy

Have you ever gone on vacation and been

sucked into buying all of those tacky souvenirs?

And then you pack to go home and your

suitcase will barely hold it all?!

Your suitcase has just become more dense than

when you left home – it has

more stuff crammed into the

same space.

Give me some examples – I don’t get it.

Batteries feel dense because they have a lot of

metal packed tightly inside.

A wooden block is about the same size (volume)

as a 9 volt battery, but it feels much lighter

because there are not as many particles inside.

I’m

more

dense

than

You!

Give me some examples – I don’t get it.

Chocolate feels dense because it has a lot of

sugar packed tightly inside.

A marshmallow that is about the same size

(volume) as the chocolate feels much lighter

because there are not as many particles inside.

Some of the particles are even air bubbles!

I’m

more

dense

than

You!

Give me some examples – I don’t get it.

Give me some examples – I don’t get it.

In MATH language…

Density is the amount of mass an object has compared to its volume

or

Density = mass volume

For Math Phobics….

A way to determine relative density it to

do the old floater / sinker test.

Water has a density of 1 g/mL.

If something floats in water, it has a

density less than 1 g/mL.

If something sinks in water, it has a

density of greater than 1 g/mL.

Do all rocks sink?

Does all wood float?

See? You already…

LOVE

density!

I love it so much…

Sometimes I even draw a heart and shoot

an arrow through it when I am

daydreaming about density.

Back to the formula…

If you squint your eyes, this sorta looks

like an

m v

Back to the formula…

Your mind is now forever corrupted – you

won’t be able to see a cupid’s heart

without thinking about density

Now, let’s put the formula to use…

The m stands for mass.

What is mass?

Mass is the amount of particles

(matter) in something.

Here on earth, that kinda means how much it weighs, since

the location is all the same.

Now let’s put the formula to use

To find the mass, use a triple beam

balance.

Or a digital scale

Now let’s put the formula to use…

What is the measurement reading on this triple beam

balance?

100 + 60 + 3.7 grams = 163.7 grams

Now let’s put the formula to use,

The V stands for volume.

What is volume?

Volume is the amount of space

that something takes up.

Now let’s put the formula to use…

To find the volume of a cubic shape, use a

centimeter ruler.

Notice that there are no markings for ½ or

¼ etc. Each little line is 0.1 centimeters.

Now let’s put the formula to use…

To find the volume of something irregular

(doesn’t have a perfect cubic shape) use

the water displacement method with a

graduated cylinder

or an overflow can.

Now let’s put the formula to use,

1- Put some water in the graduated

cylinder and make a note of how much is

in there.

2- Drop in the thing you want to measure.

3- Make a note of the new water level

reading.

4- Find the CHANGE in water level by

subtracting.

Now let’s put the formula to use…

What is the measurement reading on this

graduated cylinder?

Read from the bottom of the meniscus (the

curved bubble thing)

52 milliliters or 52 ml

Volume UNITS……

1 cubic centimeter =

1 cm3 = 1 cc =1 mL

Now let’s put the formula to use…

Calculate the density of water.

(Remember to find the mass of the

container first.)

To find the density

1 - Find the mass of the object

2- Find the volume of the object

3- Divide them

Density =

482.63 g 200 mL ≈ 2.4 g / mL

m v =

Units for density g/cm3 or g/ml

Formula: M = mass V= volume D = density

M = D x V V = M / D D = M / V

To find density:

Ex. If the mass of an object is 35 grams and it takes up 7 cm3 of space, calculate the density.

1) Find the mass of the object

2) Find the volume of the object

3) Divide : Density = Mass

Volume

To find density:

Set up your density problems like this:

Given: Mass = 35 grams Formula: D =

Volume = 7 cm3

Unknown: Density (g/ cm3) Solution: D = 35 g 7 cm3

D = 5 g/cm3

Ex. If the mass of an object is 35 grams and it takes up 7 cm3 of space, calculate the density.

1) Find the mass of the object

2) Find the volume of the object

3) Divide : Density = Mass

Volume

M V

LIQUID LAYERS

Liquid Layers

If you pour together liquids that don’t mix

and have different densities, they will form

liquid layers.

The liquid with the highest density will be

on the bottom.

The liquid with the lowest density will be

on the top.

Steve

Spangler

7 layer

density

38

Which diagram correctly represents the liquid layers

in the cylinder? Karo (K) syrup (1.4 g/mL), vegetable

(V) oil (0.91 g/mL,) water (W) (1.0 g/mL)

1 2 3

K

K

W

W

W

V

K

Learning Check

V

V

39

1)

Vegetable oil 0.91 g/mL

Water 1.0 g/mL

Karo syrup 1.4 g/mL

K

W

Solution

V

Liquid Layers

Check out this picture from your

book. Which layer has the

highest density?

Which layer has the lowest

density?

Imagine that the liquids have the

following densities:

10g/cm3 3g/cm3

6g/cm3 5g/cm3

Which number would go with

which layer?

Liquid Layers

Check out this picture from your

book. Which layer has the

highest density?

Which layer has the lowest

density?

Imagine that the liquids have the

following densities:

10g/cm3 3g/cm3

6g/cm3 5g/cm3

Which number would go with

which layer?

3g/cm3

5g/cm3

6g/cm3

10g/cm3

Liquid Layers

Which liquid has the

highest density?

Which liquid has the

lowest density?

Which liquid has the

middle density?

Liquid Layer

Which liquid has the

highest density?

Golden syrup

Which liquid has the

lowest density?

oil

Which liquid has the

middle density?

water

Liquid Layers – Try on your own!

Imagine that the

liquids on the right

have the following

densities:

15g/cm3 10g/cm3

3g/cm3 9g/cm3

7g/cm3 12g/cm3

Match the colors to

the correct densities.

3g/cm3

7g/cm3

9g/cm3

10g/cm3

12g/cm3

15g/cm3

45

Sink or Float

• Ice floats in

water because

the density of ice

is less than the

density of water.

• Aluminum sinks

because its

density is

greater than the

density of water. Copyright © 2005 by Pearson Education, Inc.

Publishing as Benjamin Cummings

Liquids: Corn syrup is most dense, the water, then oil is least dense.

The Nut sinks to the bottom. It is the most dense material in the cup.

The grape is more dense than water and oil, but less dense than corn syrup.

The lego is more dense than oil, but less dense than water.

The styrafoam is the least dense material in the cup.

Video: ZOOM - Making Eggs Float

Science will save the galaxy!

Don’t be dense!