2. What is density? Density is a comparison of how much matter there is in a certain amount of space or volume. Density is a physical property of all materials and all phases of matter (solid, liquid, gas, plasma). Density is determined by how closely packed particles are in a specific volume.

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

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

5. Density Density is the mass per unit volume of an object. Density is used to identify and classify substances (gold Vs pyrite, salt water Vs fresh water, steel Vs. aluminum, solid Vs. liquid) I love Density

6. I Love Density Density =

7. Density formula Density = Massm Volumev Units g/ml, g/cm 3, g/cc Remember 1 ml = 1 cm 3 = 1 cc ALWAYS REMEMBER UNITS

8. Group Practice Frank has a paper clip. It has a mass of 9g and a volume of 3cm 3. What is its density? Frank also has an eraser. It has a mass of 3g, and a volume of 1cm 3. What is its density?

9. Independent Practice Al’Licia has a watch. It has a mass of 4g and a volume of 2cm 3. What is the density of the watch? Mia has a wallet. It has a mass of 15g and a volume of 5cm 3. What is the density of the wallet?

10. Density Practice problems What is the density of a 42 g rectangular solid with sides that measure 2 cm, 3 cm and 1.5 cm? What is the density of a 24 g rock that has a volume of 8 ml?

11. Liquid Layers If you pour together liquids that don’t mix and have different densities, they will form liquid layers. The liquid with the highest density will be on the bottom. The liquid with the lowest density will be on the top.

12. Liquid Layers Check out this picture from your book. Which layer has the highest density? Which layer has the lowest density? Imagine that the liquids have the following densities:  10g/cm 3.3g/cm 3.  6g/cm 3.5g/cm 3. Which number would go with which layer?

13. Liquid Layers – Try on your own! Imagine that the liquids on the right have the following densities:  15g/cm 3 10g/cm 3  3g/cm 3 9g/cm 3  7g/cm 3 12g/cm 3 Match the colors to the correct densities. 3g/cm 3 7g/cm 3 9g/cm 3 10g/cm 3 12g/cm 3 15g/cm 3

14. Float or Sink The density of water is 1 g/ml Anything with a density less than one will float in water. If there are numbers to the left of the decimal it will sink!

15. So why do ships float ? The density of steel is 7.8 g/cm 3 The density of waters 1 g/cm 3 Think of a steel ship as a can that is empty and watertight. The majority of its space is taken up by nothing more than air which has a specific gravity of about 0.00129. So if a make a ship that is like a can, empty inside and watertight it floats. Its volume sufficient that it causes its specific gravity to remain below 1.0 even after adding the weight of its contents. The steel ship will remain afloat as long as its density remains below that of water. The problem is that if water is allowed to enter the ship it would sink. Ships made of steel have to be sealed so water can not get in and increase its density. Steel can float only because of the way it is shaped, the space it takes up, and the seal that keeps its watertight. The ability of steel to float is the ability of people to shape metal and solve problems by examining outcomes.

16. Review What is the formula for density? What happens if you pour together liquids that have different densities? Will the liquid on the top have the highest or lowest density? Will the liquid on the bottom have the highest or lowest density?

17. Super Scientist Questions 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? 75 ml of a liquid has a mass of 50 g. Find its density. Will this liquid sink or float in water? Explain. An object of mass 55.4 g is dropped in 40 ml of water. The water level rises to 46 ml. What is the density of the object?