1. Warm up
Find the volume of the hemisphere to the nearest whole number.
d = 20yd

2. Warm up #2

3. DENSITY
Density is defined as mass per unit volume. It is a measure of how tightly packed and how heavy the molecules are in an object. Density is the amount of matter within a certain volume.
Density is the amount of matter within a certain volume.

4. Proof that water and ice have different densities

5. To find the density 1- Find the mass of the object
2- Find the volume of the object
3- Divide Density = Mass
Volume

6. Practice #1
A suburban city has a population of 58,000 people. It has an area of 22 mi2. What is the population density in terms of people per square mile?
About 4
About 188
About 2,636
About 37,931

7. Practice #2
Mariana's swimming pool holds 22,000 gallons of water. If there are approximately 7.5 gallons per cubic foot, what size swimming pool, in terms of cubic feet, does Mariana have? Round your answer to the nearest cubic foot.
3 ft.3
2,933 ft.3
34,091 ft.3
165,000 ft.3

8. Practice #3 2.3 acres 10 acres 43.56 acres 2, 500 acres
Joe counts 250 peach trees on 25% of the land he owns. He determined that there are 10 trees for every 1,000 square feet of land. About how many acres of land does Joe own?
2.3 acres
10 acres
43.56 acres
2, 500 acres

9. Practice #4 Cone Cylinder Prism Sphere
The silo in the diagram best resembles what geometric solid?
Cone
Cylinder
Prism
Sphere

10. Cross Sections of Three-Dimensional Figures

11. Look at the example on the next page to help your understanding.
3-Dimensional figures can be cut by planes. When you cut a 3-D figure by a plane, the result is a 2-D figure.
The cross-sections of 3-D figures are 2 dimensional figures you are familiar with.
Look at the example on the next page to help your understanding.

12. A horizontal cross-section of a cone is a circle.
Can you describe a vertical cross-section of a cone?

13. A vertical cross-section of a cone is a triangle.

14. A water tower is built in the shape of a cylinder.
How does the horizontal cross-section compare to the vertical cross-section?

15. Geogebra Models
Cone
Cylinder

16. The horizontal cross-section is a circle.
The vertical cross-section is a rectangle

17. Which figure has the same horizontal and vertical cross-sections?1.
Which figure has the same horizontal and vertical cross-sections? A C B D
Answer: C

18. Which figure does not have a triangle as one of its cross-sections?2.
Which figure does not have a triangle as one of its cross-sections? A C B D
Answer: C

19. Which is the vertical cross-section of the figure shown?3.
Which is the vertical cross-section of the figure shown? A
Triangle B
Circle C
Square
Answer: C D
Trapezoid

20. Which is the vertical cross-section of the figure shown?4.
Which is the vertical cross-section of the figure shown? A
Triangle B
Circle C
Square
Answer: A D
Trapezoid

21. Which is the cross-section of the figure shown?5.
Which is the cross-section of the figure shown?
Answer: A

22. Which is the cross-section of the figure shown?6.
Which is the cross-section of the figure shown?
Answer: A