1. Chapter 9 Thermal Energy
Heat
Chapter 9 Thermal Energy

2. Kinetic and Potential Energy
Kinetic energy- energy of motion
potential energy – Is the certain amount of energy that Molecules have that is ABLE to be changed to kinetic energy

3. *Thermal Energy
Both the potential energy + the kinetic energy of all the molecules in an object is: Thermal Energy.

4. What is Temperature?
Temperature- is a measure of the average movement of molecules(kinetic energy)
(You know it as “How hot or cold something is”)
Higher temperatures mean faster moving molecules in a substance

5. Temperature Scales Three Common Temperature Scales (units)
Fahrenheit is used mainly in the United States
Celsius is based on water’s freezing and boiling points
Kelvin, uses zero as absolute zero, the lowest temperature an object can have.

6. Converting Temperatures
Convert Fahrenheit to Celsius
C = 5/9 ( Temperature in Fahrenheit - 32)
Convert Celsius to Fahrenheit
F = 9/5 ( Temperature in Celsius) + 32
Convert Celsius to Kelvin
K= Temperature in Celsius + 273
PEMDAS DOES COUNT!!!!!

7. Thermal Expansion
When most substances are heated they expand, The amount they expand depends on the material and temperature
That means the molecules speed up and tend to move farther apart
*This means things that are cooled slow down their particles, which get closer….causing it to contract or shrink

8. Heat Transfer
Chapter 9

9. What is Heat?
Heat- A form of energy (thermal) made by the motion of molecules.
The more movement of molecules the more heat energy
Heat energy has the ability to do work

10. Finishing Heat’s Definition
Heat: is thermal energy that is TRANSFERRED from one object to another when the objects are at different temperatures.
So there must be a difference in temperatures for heat to transfer!

11. DO NOT WRITE Heat & States of Matter
Solids have vibrating particles, not moving freely,
add heat and the solids melt, to liquids
Liquids have less restricted moving particles
Add heat and the liquid evaporates
To the most freely moving particles of a gas
The opposite is true when you remove heat, from gas to liquid to solid
*Thermometers

12. Transferring Heat
Heat ONLY flows from warmer objects to cooler objects
Heat NEVER flows from colder objects to warmer objects
Heat transfer occurs in three ways
Conduction
Radiation
Convection

13. Conduction Conduction- This is the transfer of heat by direct contact…
…This is done by the contact between particles of high kinetic (moving) energy to particles of low kinetic energy
Transfer will continue until all particles have the same kinetic energy and are the same temperature
Occurs more easily in solids and liquids
Example:
Attempting to eat a hot pocket and you burn your mouth

14. Radiation Radiation- Transfer of energy by electromagnetic waves.
This can occur in space or through matter since it does not require particles to transfer the energy
This is how the sun’s energy reaches Earth

15. Convection
Convection- Heat transfer that occurs in moving fluids (liquids and gases), the movement of molecules from one part of a material to another.
Hot liquids & gases rise while cold ones fall. This creates currents that carry the heat energy
Wind is caused by convection

16. Good and Poor Conductors
Conductors: material that easily transfers heat
Poor Heat Conductors
Wood
Plastic
Glass
Gases
Good Heat Conductors
-Most metals

17. Insulation
Insulation: is used to reduce the amount of heat loss by conduction
Poor Conductors are good insulators
Materials that trap air are good insulators

18. DO NOT WRITE Heat Transfer
Used in heating systems of homes and other buildings
Used in Cooling Systems too
Heating
Fireplace-Radiation
Steam Heating-Uses all 3
Hot Water Heating-Uses all 3
Electrical
Solar
Cooling
*Uses evaporation to absorb heat
Air Conditioners
Refrigerators

19. Heating an Object
Specific Heat: This is the amount of heat needed to raise the temperature of 1 kg of a substance by 1 Degree Celsius (depends on the material)
Thermal Equilibrium: This is when there is no heat movement between two things, because both objects have reached an equal amount of thermal energy.

20. Three Laws of Thermodynamics
First Law of Thermodynamics: Aka> The Law of Conservation of Energy. The amount of energy in the universe remains constant.
Second Law of Thermodynamics: Any process will tend to increase the amount of entropy (chaos) in the universe!!!!
Third Law of Thermodynamics: As the temperature approaches absolute zero, the entropy of a system approaches its minimum.