Thermal Energy and Matter

1
Thermal Energy and Matter

• Heat is the transfer of thermal energy from one
  object to another because of temperature
  differences.

2

• Temperature is a measure of how hot or cold is it
  compared to a reference point.

3
Quick Question

• How are you going to remember the difference
  between heat and temperature?

4

• Temperature is related to the average kinetic
  energy of the particles in an object due to their
  random motions through space.

5
Thermal Energy

• Thermal energy
• is the total potential and kinetic energy of all
  the particles in an object
• It depends on mass, temperature, and phase

6

• Mass
• if two containers have different mass, but the
  same temperature.
• The larger mass object will have more thermal
  energy.

7

• Temperature
• if two containers have the same mass but
  different temperatures, the higher temperature
  mass will have more thermal energy.

8

• Phase
• if two masses have the same mass and temperature
  but one is a gas and the other a liquid, the gas
  will have more thermal energy, due to the motion
  of the molecules

9
Quick Question

• List and describe the 3 things that thermal
  energy depends on.
• How are you going to remember these things?

10
Thermal Contraction and Expansion

• Matter changes its volume with a change in heat.
• Thermal expansion is when the object increases
  its volume due to a temperature increase.
• Gasses expand the most, followed by liquids then
  solids.
• Ex. Thermostats, thermometers and roads.

11
Specific Heat (J/gC)

• Specific Heat is the amount of heat needed to
  raise the temperature of one gram of a material
  by one degree Celsius.

12

• The lower a materials specific heat, the more
  its temperature rises when a given amount of
  energy is absorbed by a mass.
• The beach
• Q mc?T (Heat is in Joules, mass in grams and
  temperature change in Celsius)

13
How do you measure heat changes?

• Calorimeter
• is an instrument used to measure changes in
  thermal energy.
• uses the principle that heat flows from a hotter
  object to a colder object until they both reach
  the same temperature.

14
Energy Transfer

• Conduction
• Heat transfers by direct contact.
• Gas is slower than a solid or liquid.

15

• Thermal conductor
• is a material that conducts thermal energy well.
  (Metals)
• Thermal insulators
• conduct thermal energy poorly. (Air)

16

• R Value
• is a rating how good an insulator is. High
  value good insulator.
• Convection
• Heat transfers through differences in density.
• Gasses and liquids have a decrease in density
  when their temperature increases.

17
Heat Transfer Continued

• Radiation
• is the transfer of energy by waves moving
  through space.
• Matter is not needed.
• Example includes the sun, heat lamps and fire.

18
Quick Question

• List 3 examples of heat transfer
• List 2 examples of insulators
• Why is this important in everyday life?

19
Examples of Heat Transfer
20
Laws of Thermodynamics

• 1st Law
• energy is conserved.
• If energy is added to a system the temperature
  increases so it can be accounted for.

21

• 2nd Law
• thermal energy can flow from colder objects to
  hotter objects only if work is done on the
  system. (Refrigerator)
• 3rd Law
• Absolute Zero can not be reached.

22
Find Everyday examples of

• Heat
• Conduction
• Thermal conductor
• Thermal insulation
• Convection

• Specific Heat
• Thermal energy
• Radiation
• Laws of thermodynam-ics

23
Collage

• Cut and paste
• Label and describe
• Creative
• Present
• Describe and explain how your pictures depict the
  terms

24
Warm-up
25
Read article and complete the notes
26
Heat Engines

• External Combustion Engine
• burns fuel outside the engine to move a piston.
• Steam engine

27

• Internal Combustion Engine
• burns fuel inside the engine to move a piston.
• Car
• Four Stoke Engine

28
Heating Systems

• central heating system
• heats many rooms from one centralized location.
• Most heating systems use convection to distribute
  thermal energy.
• Most common used energy sources are electrical
  energy, natural gas, oil and coal.

29
Hot-Water and Steam

• A boiler heats water that runs through the house
  to heat it, as it cools it returns back to the
  boiler to increase its temperature.

30

• This system is similar to the Hot-Water heating
  system because
• it uses water, but
• system boils the water and the steam rises to
  heat the house and returns as water

31
Modern Types

• Electric Baseboard Heating
• uses electrical energy to heat a room.
• Hot coils heat the air near it by conduction and
  radiation creating convection currents.

32

• Forced Air heating systems
• use fans to circulate warm air through ducts to
  rooms in a building
• It uses convection currents in a room to return
  cold air back to a furnace

33
Cooling Systems

• Heat pump
• is a device that reverses the normal flow of
  thermal energy.
• Refrigerant
• is a fluid that vaporizes and condenses inside
  the tubing in a heat pump.

34

• A refrigerant is a fluid that absorbs heat, it
  vaporizes, or turns into a gas. When the
  refrigerant gives off heat, it condenses, or
  turns back into a liquid.
• Refrigerator
• Air Conditioner

35
Quick Question

• List and describe 2 types of heating systems.

36
Find Out

• What type of heating system is used at your
  house?
• What type of cooling system is used at your house?