Topic V:

I.

A. The Earth receives energy from the sun in the form of Electromagnetic Radiation.

• Energy that travels in the form of electromagnetic waves at LIGHT SPEED!

• Electromagnetic energy comes in many forms that are listed in the

Electromagnetic Spectrum

Where can you go to see the spectrum?

Example: Wave Diagram

B. Electromagnetic radiation from the Sun does several things when it hits our planet1. It can be reflected: bounces off2. It can be refracted: gets “bent” or “scattered”3. It can be absorbed: taken into the material4. It can be transmitted: allowed to pass through

Good absorbers are good emitters!

(of radiation)

Rule:

C. Different materials reflect/refract/absorb energy at different rates• Depends on:

Texture

Rough Texture = More Absorption = More Release

Color

Darker Color = More Absorption

= More Release Shiny Color = More Reflection

= Less Release

A. Radiative Balance: Earth emits the same amount of energy it receives• A dynamic equilibrium

Constantly changes but balances out!• High energy forms of radiation are transformed to lower energy forms such as infrared (sensible heat)

II.

Does Earth emit high energy radiation?(visible light or ultraviolet)

NO!!

B. Methods of Energy Transfer1. Conduction: molecules collide

with each other and vibrate• most efficient in solids• energy moves from warm to cold

2. Convection: movement of fluids (gas or liquid) that transfers energy

• warmer = less dense rises

• cooler = more dense sinks

• energy moves from warm to cold

• Diagram:

3. Radiation: PROCESS where energy travels in the form of electromagnetic waves• radiation can cause radiation!

(it transforms into another type)

Journal #31 1/6Decide whether the following show Conduction, Convection, or Radiation…

The handle of a pan is hot A warm object heats another without

contact Beach sand gets hot during the day Cold air flows in when a window is opened The upstairs floor is warmest Sunlight makes pavement warm up There is a breeze at the beach

A. Energy changes types frequently

Visible Light can become _____________.

III.

?Infrared Energy

B. Potential vs. Kinetic Energy1. Potential Energy:

• The energy an object could have(needs to be released)

based on position or state of an object

2. Kinetic Energy:

• More speed and mass = more kinetic energy

energy of movement

3. Energy can be changed back and forth from kinetic to potential, but the Total Energy stays the same Potential + Kinetic = SAME (always)

Shortest Day of the Year Sunrise: 7:22amSunset:

4:25pm (least hours of insolation)

9 Hours 3 Minutes of Daylight Beginning of Winter Season North Pole tilted away from Sun Areas within Arctic Circle

receive 24 hours of darkness Sun Directly overhead

at Tropic of Capricorn (23.5° South)

IV.

A. Energy increases molecular movement• >molecular movement >kinetic energy• leads to friction and heat of substance!

B. Joules: unit of thermal energy

C. Temperature: the measure of kinetic energy of molecules!

• Units: °C °F K

• What type of relationship is illustrated between these variables?

As the Kinetic Energy of Molecules increases, the temperature increases Type of relationship:direct

• Converting temperatures the “easy way”

• Converting from Celsius toKelvin:

Use a chart or Google!

D. Specific Heat: the resistance that a material has to the absorption and release of heat

1. Also: the exact amount of energy required to raise the temperature of 1 gram of any material by 1oC

2. High Specific Heat requires LOTS of energy to

warm up takes time to warm up & cool

down

What substance has the highest specific heat?

WATER !!

3. How can we find specific heats of different materials?

• Look it up:

4. Equation:

5. Units:

TmCQ Q = Thermal Energy

C = Specific Heat Capacity

m = Mass

ΔT = Change in Temperature

4. Units for Specific Heat: Joules per gram times degrees

Celsius (J/g •°C)

all other materials have LOWER specific heats than liquid water!

5. Since land heats up and cools off much faster than water, the Earth is heated unevenly

Land has a LOWER specific heat than water

Different materials absorb and re-release energy from the Sun at different rates - leads to uneven heating!

Which materials are absorbing more energy and which materials are reflecting more energy?

Journal #32 1/7Solve the equation for the following:

Mass Specific Heat Change in Temperature

How much thermal energy is required to raise 100 grams of water (C=4.18 J/g°C) by 25°C?

How much thermal energy is RELEASED if the same amount of water drops by 25°C?

TmCQ

(Changes in the state of matter!)A. Melting or Liquification:

• energy is gained by the material

V.

(Low)

matter changes from solid to liquid

B. Evaporation or Vaporization: matter changes from liquid to gas (vapor)

• energy is gained by the material

• Boiling Point: when a material evaporates or vaporizes at the highest rate

• evaporation occurs faster at higher temperatures

(Med)Vaporize!

C. Sublimation: solid turns directly to gas (vapor), skipping the liquid phase

Dry Ice

• energy is gained by the material• takes LOTS of energy to initiate sublimation (energy to melt + energy to vaporize)

(High)

D. Condensation: matter changes from a gas (vapor) to a liquid

• energy is lost by the material• when water condenses, it is called dew, mist, fog, or clouds

(Med)

E. Solidification or Freezing: matter changes from liquid to solid

• energy is lost from the material• Crystallization: arrangement of solid molecules in a definite pattern

(Low)

• Lithification: solidification of molten rock (magma or lava)

F. Deposition: gas or vapor turns directly into a solid, skipping the liquid phase in between

• energy is lost by the material• occurs when there is lots of vapor and a large temperature difference between two materials

(High)

Certain Mornings…Deposition is everywhere!!!

• Close Up

G. Latent Heat: energy released or absorbed during a phase change

1. Latent Heat of Fusion: (Lf)

2. Latent Heat of Vaporization: (Lv)

3. Latent Heat of Condensation: (Lc)

Energy gained during melting

Energy lost during freezing

Energy gained during evaporation

Energy lost during condensation

4. Latent Heats for Water:

H. Ideal Phase Change Graph for H2O

• Recall our discussion on radiation!!What objects are going to affect the frost because they emit radiation?

What about trees?

Trees radiate infrared energy! This prevents frost!

The Sun adds energy to the water and the frost melts (Lf) and evaporates (Lv)!

Journal #33 1/8

Which of the following requires more energy… Bringing a 200 g sample of granite from

50°C to 100°C or Bringing a 200 g sample of lead from

50°C to 100°C (SHOW TWO CALCULATIONS)

VI. Laws of Thermodynamics

A. First Law: Conservation of Internal Energy1. Internal Energy (U) in an ideal

system is CONSTANT

2. The internal energy of a system is equal to HEAT added or removed

minus any work done because of the system

3. Equation:

U = Internal EnergyQ = Heat Added or RemovedW= Work done on/by system

Example: 1st Law of Thermodynamics

The space shuttle launches and the rockets add 1 x 106 Joules of heat energy. 7.5 x 104 Joules are used to move the space shuttle upward the first 1 meter. What is the internal energy of the shuttle?

If the shuttle keeps moving and 3.75 x 106 J are used to move the shuttle, how much heat is added by the rockets?

B. Second Law: toward equilibrium1. Entropy: measure of randomness or disorder of the molecules in a system

2. The universe ALWAYS “wants” to move toward equilibrium (more entropy)

thermal energy tries to evenlymove into the system

3. Heat Energy moves from highto low! Never reversed unless

work is done!

4. Energy of a system will always decrease due to entropy and the loss is from work/ heat given to the environment

A car cannot be repaired from a crash without WORK!

Example: 2nd Law of Thermodynamics

A metal bar connects two cups of water with different temperatures. Cup A is at 90°C and Cup B is at 20°C. After a long period of time, what will the temperatures of each

cup be assuming there is no energy loss to the

environment?

Journal #33 1/10 What phase change is

occurring between points B and C?

How many Joules does each gram of water gain or lose between points D and E?

What is the name of the process occurring if heat is being taken away between points D and E?

What is happening to the water between points A and B?

How many Joules are gained by 5 grams of water between points C and D?