1. Density cont.

2. Homework

3. Objectives Explain density. Use the density formula to solve for missing values.

4. Density How does a Lava Lamp work? What does density have to do with floating?

5. Density What could be the possible uses of knowing something’s density?

6. Density Mass is the amount of matter that something has. It is not the same thing as weight. Volume is the amount of space that something takes up. Simulation

7. Density Same mass? Same volume? Same density?

8. Density Same mass? Volume? Density?

9. Density Same mass? Volume? Density?

10. Density Density = Mass / Volume Why is the unit g/mL (or g/cm 3, etc.) Physical or chemical property? Why would this happen? http://www.youtube.com/watch?v=aR0b4QRh fU0 http://www.youtube.com/watch?v=aR0b4QRh fU0

11. Density One packet of Nutrasweet sweetens a drink as much as 3 packets of sugar. A can of either type of coke has a volume of 355 mL. Both types of Coke have 355 g of non- sweetener materials. Diet Coke has.1 g of Nutrasweet. Coke has 39 g of sugar. Explain the result.

12. Buoyancy Archimedes Principle: Any object, wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object. So whether something sinks or floats depends on how much water it displaces, and since the amount of water it displaces is based upon its density, density influences sinking and floating.

13. Buoyancy 1 ft 3 (28.3 L) of fresh water has a mass of approximately 28.30 kg. Let’s say you put an object with a volume of 1 ft 3 into water, and this object has a mass of 28.58 kg. What force is the water pushing up with? What force is the object pushing down with? So does it sink or float?

14. Buoyancy 1 ft 3 (28.3 L) of fresh water has a mass of approximately 28.30 kg. Let’s say you put an object with a volume of 1 ft 3 into water, and this object has a mass of 28.58 kg. What force is the water pushing up with? What force is the object pushing down with? So does it sink or float? Now say you put that object in salt water, 1 ft 3 of which has a mass of 29.03 kg. What force is the water pushing up with? What force is the object pushing down with? So does it sink or float?

15. Density Story of Archimedes: Around 250 B.C., the Greek mathematician Archimedes was given the task of determining whether a crown that had been fashioned for the King of Syracuse was really made of pure gold. He wrestled with the problem as he relaxed into a bathing pool, and when he saw water spill over the edge of the pool upon submerging himself, arrived at his answer.

16. Density Story of Archimedes: Around 250 B.C., the Greek mathematician Archimedes was given the task of determining whether a crown that had been fashioned for the King of Syracuse was really made of pure gold. He wrestled with the problem as he relaxed into a bathing pool, and when he saw water spill over the edge of the pool upon submerging himself, arrived at his answer. An equal mass of silver occupies more space than gold, therefore, a mixed silver and gold crown would displace more water than a pure gold crown. How could you use water, gold, and silver to figure out if the crown is pure gold?

17. Density Story of Archimedes: Around 250 B.C., the Greek mathematician Archimedes was given the task of determining whether a crown that had been fashioned for the King of Syracuse was really made of pure gold. He wrestled with the problem as he relaxed into a bathing pool, and when he saw water spill over the edge of the pool upon submerging himself, arrived at his answer. An equal mass of silver occupies more space than gold, therefore, a mixed silver and gold crown would displace more water than a pure gold crown. He placed the test crown in one tub of water and a hunk of pure gold with the exact same mass in another. More water was displaced by the test crown; the king had been defrauded by the craftsman.

18. Summary What is density? How can you use the density formula to solve for missing values? (Tomorrow: we continue our long-standing thread of examining physical and chemical properties by finally zooming in on why different things have different properties…)

19. Density Practice Work time