Heat Transfer
All atoms have ____ energy.
Thermal (heat)
Thermal Energy
Thermal energy is the total kinetic and potential energy of a system due to the motion of its atoms and molecules
When rapidly moving molecules collide with molecules in another object
They will transfer some of their energy, in the form of heat, to the molecules
How is heat transferred in Convection?
Through the circulation of the air
Insulation helps homes do what?
To protect your home from losing heat energy to the outside environment
All objects absorb and emit radiation (energy). (T/F)
True
Energy is never lost (T/F)
True
Light
Visable energy
Thermal resistance is represented by
r
Three ways heat can be transferred:
Radiation, Convection, Conduction
Objects that are good absorbers of radiation are good ____ as well.
Radiators
List all the types of electromagnetic energy according to their wave frequencies, small to large.
Radio, Micro, Infrared, Visible, Ultraviolet, X-Ray, Gamma Ray
The greater the molecular shaking,
the higher the tempurature
Tempurature
The measure of how much the molecules in a substance are vibrating (motion in an object). The amount of thermal energy in an object
The method used to transfer heat is usually the one that is what?
The most efficient
Heat
The motion of the molecules in a substance. The transfer of thermal energy between two objects or systems
Radiation
The movement of Electromagnetic Energy / Radiant Energy. The transfer of energy in electromagnetic waves that can move through a vacuum.
Electromagnetic waves travel how fast?
The speed of light
Thermodynamics
The study of thermal energy
Conduction
The transfer of heat energy through the direct contact of two materials, because of the collisions of adjacent atoms or molecules
Convection
The transfer of heat energy through the movement of the molecules of a fluid, due a circular cycle in which heat rises and transfers the energy.
0 Kelvin
Absolute Zero. There is no molecular movement (-273 degrees Celsius)
Wind Chill
Accounts for how much additional heat you will lose because of convection. Usually a lower temperature than outside
Describe the cycle of convection
As a fluid is heated, its molecules expand, becoming lighter, and it rises. It is then replaced by the cold fluid, which is more dense, and sinks to the bottom. As the hot fluid rises, it will eventually lose its heat (due to it transferring it to something else or by other means) and fall aswell. Meanwhile, the cold fluid will become heated and rise like the first time. It is a continuous circular cycle.
The ______ of a conductor determine how easily heat energy moves back and forth in an object
Atomic Properties
Kelvin
Based on the molecular movement of a substance, and not on water's properties.
Why is air a poor conductor of heat
Because the molecules in gases are much farther apart than the molecules in solids
How does a microwave oven work?
By agitating the water molecules present in most objects to create heat or infrared radiant energy
Convection (Can/Cannot) occur in space
Cannot
Convection can help create ___, which supply water to the earth.
Clouds. It also carries the moisture up high, helping the water cycle
What is the only process that transfers thermal energy in a solid substance?
Conduction
Which method of heat transfer is the least significant method of heating the Earth's atmosphere?
Conduction
The sun is very ____ with its output of heat and radiation
Constant
Heat gained by conduction or radiation is moved about the planet by what?
Convection
June puts her hands over the fire to warm them. What type of heat transfer makes this possible?
Convection
How do good insulators cut down on the amount of energy used to heat a home?
Good insulators allow less heat to escape from inside to the air outside, so you do not have to expend as much energy replenishing the lost heat
Infrared Radiant Energy
Heat
Radiant Energy
Heat energy that is transferred by electromagnetic waves and does not need matter in which to travel
Frequency of Gamma Rays
High
Objects emit radiation when
High energy electrons in a higher atomic level fall down to lower energy levels
Absorption of energy in an object is higher than the emission of energy
Hotter
Energy from the sun reaches the form of
Radiation
Velocity of Propagation of a Wave
300,000 km/s
Convection Cell
A circular pattern of air rising and sinking.
What is thermal energy transferred by?
A difference in temperature between two objects
Conductor
A material that transmits energy; it is capable of gaining and losing thermal energy
Fluid
A substance in which its molecules can flow freely past each other; it does not have a fixed shape
Absorption of energy is less than the emission of energy
Cooler
Conduction occurs at _____ rates in different materials
Different
Heat Source
During conduction, the object that has a higher temperature
Heat Sink
During conduction, the object that has a lower temperature
Heat is radiated in the form of
Electromagnetic Waves
The energy lost in an object is emitted as
Electromagnetic radiation, or light
How is heat transferred during radiation?
Electromagnetically
The sun is the ultimate source of ____ for our planet
Energy
Heat is a form of
Energy (cannot be touched)
When particles of matter come in contact with one another,
Energy is transferred
Three scales of measurement for tempurature
Fahrenheit, Centigrade, Kelvin
Nicolas Leonard Sadi Carnot
Founder of the field of Thermodynamics. Studied how steam is used to power engines, and his work helped with the construction of steam engines. (He was French)
Different waves in the electromagnetic spectrum have different
Frequencies
Electromagnetic Spectrum
Includes all forms of electromagnetic radiation; the types of radiation differ in their frequencies and wavelengths
The amount of heat radiated from an object ____ as the temperature of an object _____.
Increases (for both)
Which types of energy does a fire give off?
Infrared; Visible light
Animals use ____ to keep themselves warmer and trap in body heat
Insulators
Coal (Is/Isn't) a good conductor of heat
Isn't
How do all types of Energy move through space?
It is radiated.
When a fluid is heated,
Its molecules spread out, its molecules move more quickly, its molecules gain great volume, and its molecules collide with each other more frequently (transferring energy)
Heat (thermal energy) is always transferred from an object with more molecular kinetic energy (hotter) to an object with
Less molecular kinetic energy (colder)
Frequency of Radio Waves
Low
All forms of matter are composed of atoms in constant ____.
Motion
The ____ determines how much ___ an object has
Motion; thermal energy
A better conductor of heat will have a
Much more efficient heat transfer
Is air a good conductor of heat
No
Temperature and heat are ___ the same thing
Not
Convection helps with the exchange of ____ necessary for life
Nutrients
Insulator
Poor conductor of thermal energy (or electricity. It resists the flow of heat energy.
What state of matter is the best for the conduction of heat?
Solid
What kind of material can transfer heat by conduction?
Solids, liquids, and gases.
Convection Cell are at work in
Tectonic Plates, Oceans, the Atmosphere, and many others.
Thermal Conductance (Conductivity)
The ability to conduct/allow to pass through thermal energy. Measured in the amount of thermal energy conducted in one hour. The rate at which an object transfers thermal energy
What part of the air is heated by the sun's electromagnetic waves that is radiates?
The air at earth's surface
Why are there more thunderstorms near the equator?
The air is the warmest there (because more sunlight reaches it), and there are many oceans, or other bodies of water
What will happen if a cold object comes into contact with a hotter one?
The hotter object will transfer its heat to the colder one until they are the same temperature
Centigrade
Water Freezes at 0 degrees; boils at 100 degrees
Fahrenheit
Water freezes at 32 degrees; boils at 212 degrees
Heat Transfer is measured in units of what?
Watts
Thermal Equillibrium
When two objects reach a temperature somewhere between the original temperatures (heat source and heat sink)
Can radiation travel through a vacuum?
Yes
Do all solids conduct thermal energy?
Yes, but some better than others
