2.22 Density

2.22 Density

G7 Science

Density Defined

Density is how tightly or loosely packed the particles of matter are.

Density Sinks Stuff

Water has its own level of density. Any type of matter that has a density greater than water will sink. Size doesn't matter. The apple in this video has a larger mass and volume than the penny, yet the penny sinks and the apple floats.

Multiple Choice

Which type of matter is most dense?

Multiple Select

Examine the photo of the apple particles and the penny particles. Why does the penny sink and the apple float? Select the two correct answers.

• The apple's particles are closer together than the water particles.

• The penny's particles are closer together than the water particles.

• The apple's particles are more spread out than the water particles.

• The water particles are closer together than the penny's particles.

Density Tower!

If you put different types of matter in a glass, they will organize themselves from most dense at the bottom to least dense at the top. Denser things are heavier than non dense things.

Real Life Density Tower

This scientist pours liquids into a glass in order of their densities, starting with the most dense. Then they drop some objects into the glass to see where they settle. Some of the objects are less dense than some of the liquids, but are more dense than others. Notice how they rest in the middle of the glass!

Multiple Choice

In this tower, which object is the least dense?

Multiple Select

Why does the cherry tomato end up in the middle? Choose the two correct answers.

• It is more dense than the liquids above it.

• It is less dense than the liquids above it.

• It is more dense than the liquids below it.

• Is is less dense than the liquids below it.

Multiple Choice

Why do the liquids form different layers?

• They have different densities.  
• They have different masses.  
• They have different volumes.  
• They are different temperatures.  

Multiple Choice

Helium balloons rise on Earth because:

• helium is less dense than air

• helium is more dense than air

• helium is cooler than air

• helium is warmer than air

Calculating Density

Density, mass, and volume are all related. If you know two of the three answers, you can always use math to figure out the third.

Density Formula

mass ÷ volume = density

Multiple Choice

Beon has a game controller that has a mass of 25.0 g and a volume of 29.4 cm³ What is the density of his controller? (see Beon's shirt in the pic for help).

• 49.4 g/cm³

• .85 g/cm³

• 1.176 g/cm³

• 50 g/cm³

Multiple Choice

Saniyah has a balloon animal with a volume of 100 cm³ and a mass of 4g. What is its density?

• 104 g/cm³

• .12 g/cm³

• 96 g/cm³

• 0.04 g/cm³

Physical Properties

We use intensive properties to help us identify matter because they stay the same no matter what. Density is an intensive property because it stays the same no matter what. Mass and volume are not helpful in identifying matter because they can change depending on the circumstance.

Multiple Select

Check all the properties below that help us identify matter (properties that don't change no matter what).

• Boiling point

• Malleability

• Mass

• Density

• Volume

Multiple Choice

The people in this video are changing the mass and volume of the plates, but not their density. And yes, this is a real thing!

... cuz y not?

Density of Water

The density of water is generally 1 g/cm³. Anything less dense than that will float. Anything more dense than that will sink. Anything that floats has the property of buoyancy.

Density & Buoyancy

Buoyancy is the ability to float. Things with lots of mass and volume (like cruise ships) float while pennies sink. Why? because a penny is actually denser than a cruise ship. Cruise ships are mostly hollow. Very dense things sink.

Multiple Select

Dry sponge will float or sink in water?

• Sink

• Float

Multiple Select

Spoon will sink or float in water?

• Sink

• Float

Multiple Choice

Rubber band will float or sink in water?

• Float

• Sink

Multiple Select

Dry socks will float or sink in water?

• Float

• Sink

Multiple Select

Keys will float or sink in water?

• Float

• Sink

Multiple Choice

The items you just identified as things that sink in water sink because their particles are farther apart than the particles of water.

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