Chapter 2 self study

Question 1

What is energy ?

Answer 1

the ability or capacity to do work on some form of matter

Question 2

What is potential energy?

Answer 2

is the stored energy in a mass that has the potential to do work

PE = mgh where
m → mass
g → gravity (9.8 m/sec2)
h → height above ground

Think of a lake behind a dam.(Gravitational PE)

The burning of fossil fuels (coal, petroleum)
The consumption of food(Chemical PE)

Question 3

What is Kinetic Energy?

Answer 3

KE = ½mv2
m → mass
v → velocity

Kinetic energy is the energy of motion

Any moving object possesses kinetic energy
The faster an object moves, the greater the kinetic energy

If same speed, the object with greatest mass would have more kinetic energy

Heat energy → molecular motion

Radiant energy → that received from the sun

Question 4

First Law of Thermodynamics

Answer 4

This is the law of conservation of energy.

The total amount of energy in the universe remains constant.

Energy cannot be created nor can it be destroyed.

Question 5

What is temperature a measure of ?

Answer 5

The temperature is a measure of a substance’s average kinetic energy

or

temperature is a measure of the average speed of the atoms and molecules (molecular motion).

Warm air → molecules farther apart/volume
Less dense
Cold air → molecules closer together/volume
More dense

Question 6

What are the 3 transfers of heat ?

Answer 6

Conduction, convection and radiation

Question 7

What is heat?

Answer 7

Heat is energy in the process of being transferred from one object to another because of the temperature difference between the two objects (warm → cold).

Question 8

After heat is transferred where is it stored?

Answer 8

Internal energy

Question 9

What is the absolute zero temperature?

Answer 9

-273C(-459F)

Question 10

Specific Heat

Answer 10

The heat capacity of a substance per unit mass.

Scientifically, specific heat is the amount of heat (energy) needed to raise the temperature of 1 gram of substance 1˚C.

Question 11

Latent Heat

Answer 11

Latent heat is the heat energy required to change a substance from one state (phase) to another.
water vapor ↔ liquid water
liquid water↔ ice
water vapor ↔ ice

Question 12

Freezing (Latent Heat Number)

Answer 12

+80cal/gr

+ heat energy added to the environment

Question 13

Evaporation

Answer 13

is a cooling process

Energy is lost when faster moving molecules escape, this brings down the average molecular motion of the water droplet

The water droplets will cool along with the surrounding air

Question 14

Condensation

Answer 14

is a warming process

The lost energy (hidden) is released when the water vapor condenses back to a liquid

This released energy will warm the air around the newly formed water droplets

Question 15

Conduction

Answer 15

The transfer of heat from molecule to molecule within a substance.

Heat flows from warmer to colder regions

Generally, the greater the temperature difference, the more rapid the heat transfer

Metals are good heat conductors because their molecules are structurally bonded together.
Air is an extremely poor conductor of heat

Question 16

What provides a tremendous amount of energy for storms such as hurricanes, mid-latitude cyclones and thunderstorms?

Answer 16

Latent Heat

Question 17

Convection

Answer 17

Convection → The transfer of heat by the mass movement of a fluid (water & air)

Water & air can move freely allowing currents to set up within them
Convection happens naturally in the atmosphere

Vertical motion is “convection”

Horizontal motion is “advection”

Question 18

Thermal

Answer 18

is a rising bubble of air that carries

heat energy upward by convection

Question 19

Radiation (Radiant Energy)

Answer 19

Energy received from the sun and all things whose temperature is above absolute zero.

Radiation travels in the form of waves that release energy when they are absorbed by an object.

Because these waves have magnetic and electrical properties, they are called “electromagnetic waves”
Longer waves carry less energy than shorter waves

Question 20

Electromagnetic Waves

Answer 20

They do not need molecules to propagate (can travel through a vacuum → space)

In a vacuum they travel at a constant speed (the speed of light → ≈186,000 miles/sec

Question 21

Wavelength (λ)

Answer 21

The distance measured along a wave from one crest to another.

Question 22

Micrometer (μm)

Answer 22

Equal to one-millionth of a meter (m) or 10-6m

Question 23

Stefan – Boltzmann Law

Answer 23

As the temp of an object increases, more total radiation is emitted each second.

E = σT4

E → max rate of radiation emitted by each m2 of surface area in Watts (W)

σ → (sigma) Stefan – Boltzmann constant 5.67×10-8 W/m2K4

T → objects surface temperature in Kelvin

Question 24

The Balancing Act

Absorption, Emission & Equilibrium

Answer 24

All objects not only radiate (emit) energy but they absorb it as well.

Objects that emit more energy than they absorb get colder

Objects that absorb more energy than they emit get warmer

Objects that emit and absorb energy at equal rates hold a constant temperature (Radiative Equilibrium)

Question 25

Absorption Characteristics

Answer 25

The rate at which something radiates and absorbs energy depends strongly on its surface characteristics:

Color
Texture
Moisture content
Temperature

Question 26

Atmospheric Absorption

Answer 26

Solar radiation (shortwaves) passes rather freely through earth’s atmosphere, but the earth’s re-emitted

infrared radiation(longwaves) energy either fits through a narrow window or is absorbed by greenhouse gases and re-radiated toward earth.

Question 27

Atmospheric Window

Answer 27

Between 8 and 11μm neither water vapor nor CO2 readily absorb these wavelengths in the Infrared Radiation (longwave) scale. Because this energy passes upward through the atmosphere and out into space, this wavelength range is known as the “atmospheric window”.