1. Aim: How can we explain density?

2. What is density?
Density is a comparison of how much matter there is in a certain amount of space.

3. Which one is more dense?
How about this: Which square is more dense?

4. Which one is more dense?
Now which one is more dense?

5. THE EQUATION
D = M V
Mass
Volume
Density =

6. Units for Density
_g_
cm3

7. Let’s try a density problem together
Frank has a paper clip. It has a mass of 9g and a volume of 3cm3. What is its density?
Frank also has an eraser. It has a mass of 3g, and a density of 3 g/cm3. What is its volume?
_9 g_
3 cm3
= 3 g/cm3
_3 g_
3 g/cm3
= 1 cm3

8. Work on these problems with your neighbor.
Jack has a rock. The rock has a mass of 6g and a volume of 3cm3. What is the density of the rock?
Jill has a gel pen. The gel pen has a density of 4 g/cm3 and a volume of 2cm3. What is the mass of the pen?
_6 g_
3 cm3
= 2 g/cm3
4 g/cm3 x 2 cm3
= 8 g

9. Density relationships:
à    Objects that are more dense will sink through objects that are less dense.
à    Objects that are less dense will float on objects that are more dense.
à    Objects with the same density will remain suspended in the liquid.

10. When will an object’s density change?
If you increase the overall volume.
What might cause this?
HEAT
Example:
HOT AIR BALLOON
What will happen to that gas?
RISE

11. If cold:
Matter: gets closer
Volume: decreases
Density : increases

12. Matter: gets farther apart Volume: increases Density : decreases
If warm:
Matter: gets farther apart
Volume: increases
Density : decreases

13. Density of Water Water has a density of 1 g/cm3.
What happens when water freezes?

14. Remember….
A smaller or larger piece of the same substance will have the same density!

15. 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?