Part II: Properties of Matter
Chapter 12
Solids
(Just the section on “Density”)
17-Mar-16
Physics 1 (Garcia) SJSU
Demo: Iron and Cork
What is heavier, iron or cork?
Small iron nail
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.
17-Mar-16
Physics 1 (Garcia) SJSU
BIG BAG
OF
CORK
Density
Define density as mass per volume,
( Density ) =
( Mass )
( Volume )
Densities ( in grams per cubic centimeter ):
Gold: 19.3 Mercury: 13.6 Lead: 11.3
Iron: 7.9
Water: 1.0
Cork: 0.2
(See Table 12.1, page 232)
Liquids
17-Mar-16
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…
17-Mar-16
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.
17-Mar-16
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?
17-Mar-16
Physics 1 (Garcia) SJSU
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
Density drops on freezing
17-Mar-16
Physics 1 (Garcia) SJSU