Density Lesson

Density is a measure of the mass of a material in a given volume.

Recall... what is mass? If you do not remember, forge ahead and review!

What is Density?

Multiple Choice

What is mass?

• How much something weighs.

• The amount of matter an object has.

• The force of gravity pulling down on you.

• A large number of objects crowded together.

Mass is defined as the amount of matter an object has. It is not affected by gravity, and doesn't change based on location.

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Mass differs from weight because weight is affected by gravity.​ Weight is the force of gravity pulling down on you.

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Mass is measured in kilograms.​

​Fun fact! You will weigh less on the moon than you do on Earth! But you will weigh more on Jupiter!

​Mass

All matter takes up space. The amount of space an object takes up is called its volume.

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Volume can be measured in cubic meters (m³), cubic centimeters (cm3), liters, and milliliters (mL​).

​What is volume?

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Rectangular objects - calculate volume by using the formula:​

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Volume = Length x Width x Height.​

​Volume is measured in different ways depending on what shape the object has.

Let's practice using this formula on the next slide.

Multiple Choice

Calculate the volume of a block that is 5 m long, 6 m wide, and 2 m high.

• 10 m³

• 30 m²

• 60 m³

• 120 m³

One way would be to put the object in liquid that is inside a graduated cylinder. The liquid in the cylinder will rise the same amount as the volume of the object.

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Subtract the final liquid volume reading from the starting volume reading to find the volume of the object.​

Science tool definition: A graduated cylinder is a tall narrow cylinder with markings used to measure volume of liquids!

​So, then, how do you measure the volume of an irregular shaped object?

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To calculate the density, use the following formula:

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Density = mass / volume​

(mass divided by volume)​

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​Scientists use density to measure matter because each material has a specific density.

Let's practice calculating density!

Multiple Choice

Calculate the density of a rock with the mass of 108 grams and a volume of 12 cm³.

• 9 g/cm³

• 0.11111 cm³/g

• I have no idea!

• 19 g/cm³

The different densities of objects determines if it will sink or float in water.

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Higher density than water will SINK!

Lower density than water will FLOAT!

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The density of water is defined as 1 gram / milliliter³​

​What makes objects sink or float?

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Now let's practice what you have learned.

Students will practice what they learned on the next few slides.

Multiple Choice

Which measure of matter depends on the force of gravity pulling on the object?

• density

• mass

• gravity

• weight

Multiple Choice

If water has a density of 1 g/cm³, what would an object with a density of 1.5 g/cm³ do in water?

• sink

• float

• I don't know

Multiple Choice

What scientific device would be used to measure the volume of an irregular object?

• beaker

• scale

• graduated cylinder

• triple beam balance

Multiple Choice

What is the density of a material that has a volume of 20 cm³ and a mass of 380 grams?

• 0.053 cm³/g

• 19 g/cm³

• 9.5 g/cm³

• 190 g/cm³