Density Review

DENSITY

vs.

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Mass- a measurement that tells us how much matter is in an object or substance

Mass is often determined using a scale. But, scales measure weight- which is the force of gravity acting on an object.

• grams (g)
• kilograms (kg)
• metric tons (t)

Some Units of Mass

0 g

140

10

130

20

120

30

110

40

100

50

90

60

70

80

On the moon, my weight is 1/6 of my weight on Earth. But, my mass is 60 grams everywhere in the universe.

This scale does not accurately show the lime's mass on the moon because it is not callibrated for the moon's gravity!

This scale is marked (callibrated) to tell us the mass (in grams) of the object on Earth, based on its weight.

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Volume- how much space an object or substance takes up

• milliliters (ml)
• liters (L)
• cubic centimeters (cm³)

Some Units of Volume

Note: 1 milliliter (ml) is equal to the volume of 1 cubic centimeter (cm³).

The volume of the water is 30.0 milliliter. The volume of the water + the grape is 38.0 milliliters. The volume of the grape must be 8.0 ml.

38.0 ml

30.0 ml

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Density- the amount of matter in a given amount of space

Density =

Mass

Volume

To find the density of an object, divide its mass by its volume.

The rock is much more dense than the marshmallow!

Mass = 7.2 grams

Volume = 30.0 cm

Density = 0.24 g/cm

Some Units of Density

The units of density are a mass unit (such as kg) over a volume unit (such as L).

• grams per cubic centimeter (g/cm³)

• grams per milliliter (g/ml)
• kilograms per cubic meter (kg/m³)

• kilograms per liter (kg/L)

Mass = 90.0 grams

Volume = 30.0 cm

Density = 3.00 g/cm

CONTINUE

What floats?

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(Least Dense)

(Most Dense)

An object or substance will sink in substances it is more dense than and float in substances it is less dense than.

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Concept Review

Mass

Volume

Density

Mass = 7.2 grams

Mass = 90.0 grams

What Floats?

Volume = 30.0 cm

Volume = 30.0 cm

Which takes up more space?

The Marshmallow

The marshmallow and rock take up the same amount of space.

The Rock

Correct! Both the marshmallow and the rock have a volume of 30.0 cm . Therefore, they take up the same amount of space.

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Concept Review

Mass

Volume

Density

What Floats?

Mass = 7.2 grams

Mass = 90.0 grams

Volume = 30.0 cm

Volume = 30.0 cm

Which is made up of more matter?

The Marshmallow

The marshmallow and rock are made up of the same amount of matter.

The Rock

Back

Yes! The rock has a mass of 90.0 grams. Therefore it is made up of 90.0 grams of matter, much more than the marshmallow's 7.2 grams of matter.

Concept Review

Mass

Volume

Density

What Floats?

Mass = 7.2 grams

Mass = 90.0 grams

Volume = 30.0 cm

Volume = 30.0 cm

Density is the amount of matter in a given volume.

Which object is more dense, the marshmallow or the rock?

The Marshmallow

The marshmallow and rock are the same density.

The Rock

Back

You are right! The rock is much more dense than the marshmallow. Each cubic centimeter of the rock containsmore matter than each cubic centimeter of the marshmallow.

Concept Review

Mass

Volume

Density

What Floats?

Mass = 90.0 grams

Mass = 7.2 grams

Volume = 30.0 cm

Volume = 30.0 cm

Density = ?

What is the density of the marshmallow?

Hint: To determine the density of any object or substance, divide its mass by its volume.

4.2 g/cm

1.0 g/cm

0.24 g/cm

Help

Back

Yes! When we divide the mass of the marshmallow (7.2 grams) by its volume (30.0 cm ), we get that the density is 0.24 grams/cm .

Concept Review

Mass

Volume

Density

What Floats?

Mass = 7.2 grams

Mass = 90.0 grams

Volume = 30.0 cm

Volume = 30.0 cm

Density = 0.24 g/cm

Density = ?

What is the density of the rock?

Hint: To determine the density of any object or substance, divide its mass by its volume.

4.20 g/cm

3.00 g/cm

1.00 g/cm

Yes! When we divide the mass of the rock (90.0 grams) by its volume (30.0 cm ), we get that the density is 3.00 grams/cm .

Back

Concept Review

Mass

Volume

Density

What Floats?

Mass = 7.2 grams

Mass = 90.0 grams

Volume = 30.0 cm

Volume = 30.0 cm

Density = 0.24 g/cm

Density = 3.00 g/cm

Which would sink when it lands in a pond?

Note: Water has a density of 1.0 g/cm

Neither

Both

The Marshmallow

The Rock

Back

That's right! The stone sinks in water because it more dense than water. The marshmallow floats in water because it is less dense than the water.

Concept Review

Mass

Density of water = 1.0 g/cm

Density of the marshmallow = 0.24 g/cm

Density of the rock = 3.00 g/cm

Volume

Density

What Floats?

Great Work on completing this interactive. Come back to this review any time!