2

TemperatureTemperatureTemperature is a measure of how hot or cold an object is

Ice Water 0o C 32o F 273o K

Boiling Water 100o C 212o F 373o K

Room Temp 20o C 68o F 293o KBody Temp 37o C 99o F 310o K

Absolute Zero -273o C -459o F 0o K

F = 9/5 C + 32 K = C + 273

Pressure and TemperaturePressure and Temperature

Boiling WaterIce Water

Pressure Gage

Constant Air Volume

0o C

Pressure Decreases

Pressure Increases

Absolute ZeroAbsolute Zero

Ice Water 273o K

Boiling Water 373o K

Absolute Zero

0o K

Temperature (o C)

0o C

-273o C

Quantity of HeatQuantity of HeatQuantity of Heat = Mass x Specific Heat x Temperature Change

Q = m c ΔT1 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 Loss = Heat Gain

mH cHΔTH = mC cCΔTC

Heat Flow

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

mH = 500 g

TH = 90.0oC

CH = .30 cal/goC

mC = 200 g

TC = 10.0oC

CC = 1.0 cal/goC

TE = ?

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

Hot Object Cold Object

Heat Flow

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?

Sample Problem 2

mH = 800 g

TH = 100.0oC

mC = 200 g

TC = 10.0oC

TE = 40.0oC

CC = 1.00 cal/goC

CH = __ cal/goC

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

Cold WaterHot Metal

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 ?

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

1. Aluminum 2.4 cm per km

2. Brass 2.0 cm per km

3. Copper 1.7 cm per km

4. Steel 1.2 cm per km

5. Glass 0.4-0.9 cm per km

The following materials are listed in alphabetical order. Arrange them in order of their rate of linear expansion per oC from lowest to highest.

AluminumBrassCopperGlassSteel

Expansion of Water

Conductivity

TH TCH

L

H increases as (TH – TC) increases

H = depends on the type of material

H decreases as L increases

H is the heat flow between hot (TH) and cold ( TC) objects

Top 7 Conductors of Heat1. Silver 406

2. Copper 385

3. Aluminum 205

4. Brass 109

5. Steel 50

6. Lead 35

7. Mercury 8

Aluminum Brass Copper Lead Mercury SilverSteel

The following metals are listed in alphabetical order. Arrange them in order of conductivity from best to worst.

Top 10 Heat Insulators 1. Styrofoam .012. Air .0243. Cork .044. Felt .045. Fiberglass .046. Rock Wool .047. Wood .128. Brick .69. Concrete .810. Glass .9

Air BrickConcrete Cork Felt FiberglassGlassRock WoolStyrofoamWood

The following insulators are listed in alphabetical order. Arrange them in order of insulation from best to worst.

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.

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.

Night

Convection Currents and the Earth

RadiationRadiation

• 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

S= 10 cm

S = 2 cmV= 8 cm3

A = 24 cm2

V= 1 cm3

A= 6 cm2

V= 1000 cm3

A = 600 cm2

A/V = 6

A/V = .6

A/V = 3

2

Ice WaterSteam

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.

Change of State

3

Change of Phase

-40

-20

0

20

40

60

80

100

120

140

0 20 40 60 80 100

time

Deg

rees

Cel

sius

Series1

Water to Steam

Ice to Water

Water

Ice

Steam

The Human Body -Thermodynamic System

External Work

Internal Work

Food

Heat OutHeat In

Energy Change = (Food +Heat In) – (External Work + Heat Out + Internal Work)

Thermodynamics and Weight Loss

External Work

Internal Work

Food

Heat OutHeat In

Energy Change = Food + Heat In – External Work - Heat Out - Internal Work

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.

If Energy Change = 0, then you maintain your body weight.