1. Objective: How is density determined?

2. What is Density?
Which one is more dense, a bowling ball or a soccer ball?
Even though they are both approximately the same size and shape, the bowling ball is much more dense.

3. Density Density is the amount of mass in a given a space
Density = Mass
Volume

4. Visual Hot Air More energy, molecules are moving faster
Molecules are more spread apart
Which sample shows warmer air?

5. Let’s go the party
The two rooms are the same size. 50 people come to one party and 37 people come to the other party. Which one is more dense

6. Let’s put it all together…
DENSITY is the ratio of the mass of a substance to the volume of the substance
UNITS: commonly expressed as grams per cubic centimeter for solids and liquids and grams per liter for gases

7. Find the Density of the Cube
8 cm
Volume= LxWxH=
10x3038= 240 cm3
Mass = 480 grams
3 cm
10 cm

8. Density Problems
Calculate the density of a rock that has a mass of 40 grams and a volume of 5 cm3.
40g/5 cm3 = 8 g/cm3

9. Density Facts
The Density of a substance remains the same regardless of size, shape, or mass of sample!!!
Example: The density of a piece of aluminum is 2.7 g/cm3.
If you cut the Al bar in half, the density of each piece is still 2.7 g/cm3
Even if you roll the aluminum into a sheet the density will still remain the same

10. By simply cutting the bar in half, the density remains the same!!!
Density of Aluminum
D = 2.7 g/cm3
D = 2.7 g/cm3
By simply cutting the bar in half, the density remains the same!!!

11. What will change the density of an object?
Temperature
As the temperature of a substance INCREASES the density DECREASES due to the expansion of the substance
Inverse Relationship
Most substances EXPAND when heated
and CONTRACT when cooled

12. Warm air rises because it is LESS dense
Cold air sinks because it is MORE dense

13. Material DENSER than water will SINK in water
Material LESS DENSE than water will FLOAT
Materials with a density EQUAL TO water may remain at ANY LEVEL
When several objects of different densities float on water, the LEAST DENSE objects float HIGHEST.

14. B A C D Water: 1 g/ml Object D: 2 g/cc Object C: 1 g/cc
Object B: g/cc
Object A: g/cc
Why is object D sinking
Why is object A floating B A C D

15. How do we measure the MASS of an object?

16. How do we measure the VOLUME of a cube?