1. Density

2. Density compares the mass of an object to its volume
What is density?
Density compares the mass of an object to its volume

3. Which one is more dense? Demonstration: People in a square
How about this: Which square is more dense?
How do you know?

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

5. What is density? Density = mass OR. volume Units for density: g cm3
Why are these the units for density?
ALWAYS REMEMBER UNITS!

6. a formula To find volume, use… water displacement 1. V = p r2 h
V = l w h 2.
water displacement
V = ?
Vfinal
Vinit
Vobject = Vfinal – Vinit

7. Equation of a Straight Line
y = mx + b
Slope
Y intercept

8. Slope of a Straight Line
The Slope of a straight line shows how steep a straight line is.
Calculate: Divide the change in height by the change in horizontal distance
Slope = Change in Y
Change in X

9. Examples:
Mass (g)
Slope = 3 g = 1 g
3mL mL
density
Volume (mL)
Slope = density = 4 g = 2 g
2mL mL
Mass (g)
Volume (mL)

10. Solving problems in science using the GUESS strategy
Given
Unknown
Equation
Substitute
Solve

11. 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 density of 3g/cm3, and a volume of 2cm3. What is its mass? G U E S
m= 9 g
V= 3 cm3 D
D= M V
D = 9g
3 cm3
3 g
cm3 G U E S
d= 3 g/cm3
V= 2 cm3 M
D= M V
3 = m 2
6 g

12. Liquid Layers – Try with your neighbor
Which liquid has the highest density?
Which liquid has the lowest density?
Which liquid has the middle density?

13. Liquid Layers Check out this picture.
Which layer has the highest density? How do you know?
Which layer has the lowest density?
Imagine that the liquids on the right have the following densities:
15g/cm g/cm3
3g/cm g/cm3
7g/cm g/cm3
Match the colors to the correct densities.
3g/cm3
7g/cm3
9g/cm3
10g/cm3
12g/cm3
15g/cm3