1. Calculating Density

2. 1. What is Density? a. What is the same about these objects?

3. 1a. What is the same about these objects? Answer: These soda bottles all have the same volume.

4. 1. What is Density? b. What is different about these objects?

5. 1b. What is different about these objects? Answer: These soda bottles contain different samples of matter (cotton balls, water, iron filings, and air.)

6. 1c. What is Density? Density is the amount of mass (or matter) per volume.

7. 2. Which of the bottles is the MOST DENSE?

8. Answer: The soda bottle full of iron filings is the MOST DENSE.

9. 2. Which of the bottles is the LEAST DENSE? Answer: The soda bottle full of air is the LEAST DENSE.

10. 3. How is DENSITY calculated? We use the formula: Density = mass/Volume

11. 4. The DENSITY formula can be remembered using this trick: Draw a T-Triangle on your paper:

12. 4. The DENSITY formula can be remembered using this trick: Inside the T-Triangle add the three letters from the Density formula. D = m/V Think: but put a D in place of the T. m DV

13. 5. Using the DENSITY T-Triangle Cover the D on the Density T-Triangle. What is left is the formula for Density! D = m/V m DV

14. 5. Using the DENSITY T-Triangle Cover the m on the Density T-Triangle. What is left is the formula for mass! m = DV m DV

15. 5. Using the DENSITY T-Triangle Cover the V on the Density T-Triangle. What is left is the formula for Volume! V = m/D m DV

16. 6. Let’s solve a problem using the DENSITY T-Triangle! Example #1. What is the density of an object with a mass of 50 g and a volume of 100 cm 3 ? What is the formula for Density? m DV

17. 6. Here’s how you solve the problem. Example #1. What is the density of an object with a mass of 50 g and a volume of 100 cm 3 ? FormulaSubstitute Solve (1) D = m/V (2) D = 50 g / 100 cm 3 (3) D = 0.5 g/cm 3

18. 7. Let’s solve another problem using the DENSITY T-Triangle! Example #2. What is the mass of an object with a density of 1.2 g/mL and a volume of 0.3 mL? What is the formula for mass? m DV

19. 7. Here’s how you solve the problem. Example #2. What is the mass of an object with a density of 1.2 g/mL and a volume of 0.3 mL? FormulaSubstitute Solve (1) m = DV (2) m = 1.2 g/mL X 0.3 mL (3) m = 0.36 g Notice: The like terms (mL) were cancelled so only “g” was left for the answer!

20. 8. Let’s solve another problem using the DENSITY T-Triangle! Example #3. What is the volume of an object with a density of 3 g/cm 3 and a mass of 30 g? What is the formula for volume? m DV

21. 8. Here’s how you solve the problem. Example #3. What is the volume of an object with a density of 3 g/cm 3 and a mass of 30 g? FormulaSubstitute Solve (1) V = m/D (2) V = 30 g X 3 g/cm 3 (3) V = 10 cm 3 Notice: The like terms (g) were cancelled so only “cm 3 ” was left for the answer!

22. 9. Important things to remember: a. Water has a density of 1 g/mL b. 1 gram of water has a volume of 1 mL c. 1 g = 1 mL (Water only!) d. cm 3 and mL are the same thing and therefore interchangeable!

23. 10. Solve these problems. Example #4: What is the mass of an object with a density of 5 g/cm3 and a volume of 15 mL? Example #5: What is the density of an object with a mass of 300 g and a volume of 30 mL? Example #6: What is the volume of an object with a mass of 25 g and a density of 5 g/mL?

24. When you are finished… …turn this paper in to your teacher. BONUS #1: How do you know the iron filings bottle has more density? HINT: What part of the Density Formula changes from bottle to bottle?

25. THE END BONUS #2: If the feather and the elephant were the same size, which one would be less dense? Why?