70 likes | 199 Views
Part II: Properties of Matter. Chapter 12 Solids. (Just the section on “Density”). Small iron nail. BIG BAG OF CORK. Demo : Iron and Cork. What is heavier, iron or cork? Depends on how much you have. A big bag of cork can weigh more than a small iron nail.
E N D
Part II: Properties of Matter Chapter 12Solids (Just the section on “Density”) Physics 1 (Garcia) SJSU
Small iron nail BIG BAG OF CORK Demo: Iron and Cork What is heavier, iron or cork? Depends on how much you have. A big bag of cork can weigh more than a small iron nail. Think of iron as being heavier because it is heavier for the same volume. Physics 1 (Garcia) SJSU
Density Define density as mass per volume, ( Density ) = Densities ( in grams per cubic centimeter ): Gold: 19.3 Mercury: 13.6 Lead: 11.3 Iron: 7.9 Water: 1.0 Cork: 0.2 ( Mass ) ( Volume ) (See Table 12.1, page 232) Liquids Physics 1 (Garcia) SJSU
Demo: Gold Brick Compute density of gold brick. Dimensions: (20.5 cm)x(10 cm)x(5 cm) Volume: 1025 cubic centimeters (= 1.025 liters) Mass: 11,600 grams (about 26 pounds) Density = (11,600) / (1025) = 11.3 g/cm3 Check with table that this is density of… Physics 1 (Garcia) SJSU
Demo: Fool’s Gold Use displacement to find irregular volumes. Pyrite (called Fool’s Gold) is an iron ore (FeS2). Pyrite sample has: Mass: 61 g Volume: 12 cm3 Density =( 61 ) / ( 12 ) = 5.1 g/cm3 About a quarter the density of real gold. Physics 1 (Garcia) SJSU
Check Yourself Water expands when it freezes into ice. Which has more volume, kilogram of ice or kg of water? Which has more mass, a kg of ice or a kg of water? Which has a higher density, water or ice (or the same)? Which has more mass, a liter of ice or a liter of water? Physics 1 (Garcia) SJSU
Density drops on freezing Density of Water One liter of water (1000 cm3) has a mass of one kilogram (1000 grams) so density of water is 1.0 g/cm3. Density of water varies slightly with temperature, becoming less dense as temperature rises. Warm water rises and cold water sinks. Density of ice = 0.92 g/cm3 Physics 1 (Garcia) SJSU