Density EQ: Why do some objects float and other objects sink?

Density

EQ: Why do some objects float and other

objects sink?

What is density?

.

Density is a comparison of how much matter there is in a certain amount of space.

Each substance has a specific density.

Density can be used to identify a substance

Substance Density (at 20°C

Wood 0.70 g/cm3

Corn oil 0.92 g/cm3

Water 1.00 g/cm3

Rubber 1.34 g/cm3

Copper 8.80 g/cm3

Which one is more dense?

Demonstration: People in a square

How about this: Which square is more dense?

Which one is more dense?

Now which one is more dense?

What is density?

ALWAYS REMEMBER

UNITS!

Let’s try a density problem together

Frank has a paper clip. It has a mass of 9 g and a volume of 3 cm3. What is its density?9 g ÷ 3 cm3 = 3 g/cm3

Frank also has an eraser. It has a mass of 3 g, and a volume of 1 cm3. What is its density?3 g ÷ 1 cm3 = 3 g/cm3

Work on these problems with your neighbor.

Jack has a rock. The rock has a mass of 6 g and a volume of 3 cm3. What is the density of the rock?

Jill has a gel pen. The gel pen has a mass of 8 g and a volume of 2 cm3. What is the density of the rock?

Now, try these on your own.

Alicia has a watch. It has a mass of 4 g and a volume of 2 cm3. What is the density of the watch?

Mia has a wallet. It has a mass of 15 g and a volume of 5 cm3. What is the density of the wallet?

What if you already know density?

Use the density triangle, or DMV, to solve for the missing part.

D = M÷V

V = M÷D

M = D×V

Liquid Layers – Try with your neighbor

Which liquid has the highest density?

Which liquid has the lowest density?

Which liquid has the middle density?

Liquid Layers – Try on your own!

Imagine that the liquids on the right have the following densities:15 g/ml 10 g/ml3 g/ml 9 g/ml7 g/ml 12 g/ml

Match the colors to the correct densities.

3 g/ml

7 g/ml

9 g/ml

10 g/ml

12 g/ml

15 g/ml

Super Scientist Question of the Day

Jake has a book, a ruler, and a balance. How can Jake find the density of the

book with the tools he has?