2
Temperature
Temperature is a measure of how hot or cold an object is
Ice Water
Boiling Water
Body Temp
Room Temp
Absolute Zero
F = 9/5 C + 32
0o C
100o C
37o C
20o C
-273o
C
32o F
212o F
99o F
68o F
-459o F
K = C + 273
273o K
373o K
310o K
293o K
0o K
Pressure and Temperature
Pressure Gage
Constant Air Volume
Pressure Increases
Pressure Decreases
0o C
100o C
Ice Water
Boiling Water
Absolute Zero
100o C
0o C
Boiling Water
Ice Water
Temperature (o C)
-273o C
0o K
Absolute Zero
373o K
273o K
Quantity of Heat
Quantity of Heat = Mass x Specific Heat x Temperature Change
Q = m c ΔT
1 calorie is the amount of heat energy necessary to
raise 1 gram of water 1 celsius degree.
Specific Heat (Capacity) is the amount of heat energy
necessary to raise 1 gram of a substance 1 celsius degree.
1 calorie = 4.18 joules
1 Calorie = 1,000 calories = 4,180 joules
Calorimetry
Hot Object
Cold Object
Heat Flow
Heat Loss = Heat Gain
mH cHΔTH = mC cCΔTC
mH = mass of hot object
cH = specific heat of hot object
ΔTH = temperature change of hot object
mC = mass of cold object
cC = specific heat of cold object
ΔTC = temperature change of cold object
Sample Problem 1
500 g of metal at 90.0o C is placed
in 200 g of water at 10.0o C.
The specific heat capacity of the
metal is .30 cal/goC. What is the
final equilibrium temperature of
the water and metal?
mH = 500 g
TH = 90.0oC
CH = .30
cal/goC
mC = 200 g
TC = 10.0oC
CC = 1.0
cal/goC
TE = ?
Hot Object
Cold Object
Heat Flow
Heat Loss = Heat Gain
mH cHΔTH = mC cCΔTC
500(.30)(90- TE) = 200(1.0)(TE - 10)
150 (90- TE) = 200 (TE - 10)
13500- 150TE = 200 TE - 2000
350TE = 15,500
TE = 44.3 oC
Sample Problem 2
800 g of metal at 100.0o C is placed
in 200 g of water at 10.0o C. The
final equilibrium temperature of
the water plus metal is 40.0oC.
What is the specific heat capacity
of the metal ?
mH = 800 g
TH = 100.0oC
mC = 200 g
TC = 10.0oC
TE = 40.0oC
CC = 1.00 cal/goC
CH = __ cal/goC
Hot Metal
Cold
Water
Heat Loss = Heat Gain
mH cHΔTH = mC cCΔTC
800 (CH)(100- 40) = 200(1.0)(40 - 10)
48,000 (CH) = 6,000
CH = .125 cal/goC
Thermal
Expansion
Linear Expansion
Lo
ΔL
ΔL = is proportional to ΔT
ΔL = is proportional to Lo
ΔL = depends on the type of material
Volume Expansion
ΔV = is proportional to ΔT
ΔV = is proportional to Vo
ΔV = depends on the type of material
Linear Expansion
The following materials are
listed in alphabetical order.
Arrange them in order of
their rate of linear expansion
per oC from lowest to highest.
Aluminum
Brass
Copper
Glass
Steel
1.
2.
3.
4.
5.
Aluminum 2.4 cm per km
Brass
2.0 cm per km
Copper
1.7 cm per km
Steel
1.2 cm per km
Glass 0.4-0.9 cm per km
Expansion of Water
Conductivity
TH
TC
H
L
H is the heat flow between hot (TH) and cold ( TC) objects
H increases as (TH – TC) increases
H decreases as L increases
H = depends on the type of material
Top 7 Conductors of Heat
The following metals are listed
in alphabetical order. Arrange
them in order of conductivity
from best to worst.
Aluminum
Brass
Copper
Lead
Mercury
Silver
Steel
1.
2.
3.
4.
5.
6.
7.
Silver
Copper
Aluminum
Brass
Steel
Lead
Mercury
406
385
205
109
50
35
8
Top 10 Heat Insulators
The following insulators are listed in
alphabetical order. Arrange them in
order of insulation from best to worst.
Air
Brick
Concrete
Cork
Felt
Fiberglass
Glass
Rock Wool
Styrofoam
Wood
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Styrofoam
Air
Cork
Felt
Fiberglass
Rock Wool
Wood
Brick
Concrete
Glass
.01
.024
.04
.04
.04
.04
.12
.6
.8
.9
Sea Breezes and Convection Currents
Day
During the day, the land is hotter
and the air rises above the land
and is replaced by the cooler air
from above the water.
Night
During the night, the land cools faster
and the air rises above the warmer
water and is replaced by the cooler
air from above the land.
Convection Currents and the Earth
Radiation
•
A good radiator of heat is a good absorber of heat.
•
Dark colored objects radiate and absorb heat better
than light colored objects.
•
The rate of heat radiation increases with temperature.
•
The rate of heat radiation or absorption is proportional
to the surface area of the object radiating or absorbing.
Scaling and Heat Radiation
S = 1 cm
A= 6 cm2
A/V = 6
V= 1 cm3
S = 2 cm
A = 24 cm2
A/V = 3
V= 8 cm3
S= 10 cm
A = 600 cm2
V= 1000 cm3
A/V = .6
Change of State
2
Steam
Ice
Water
Heat
Heat
80 calories added to 1 g of ice at 0oC will convert the
ice to 1gram of water at 0oC.
540 calories added to 1 g of water at 100oC will convert
the water to 1gram of steam at 100oC.
3
Degrees Celsius
Change of Phase
140
120
100
80
60
40
20
0
-20 0
-40
Water to Steam
Ice to
Water
Ice
Steam
Series1
Water
20
40
60
time
80
100
The Human Body -Thermodynamic System
External Work
Food
Heat Out
Heat In
Internal Work
Energy Change = (Food +Heat In) – (External Work + Heat Out + Internal Work)
Thermodynamics and Weight Loss
External Work
Food
Heat Out
Heat In
Internal Work
Energy Change = Food + Heat In – External Work - Heat Out - Internal Work
If Energy Change = 0, then you maintain your body weight.
If Energy Change > 0, then you gain weight.
If Energy Change < 0, then you lose weight.
If 1 once fat is equivalent to approximately 300 Calories of energy, we can
calculate weight loss on a daily or monthly basis based on ΔU value.