1. Pretest - Chapter 16
1. What kind of energy is released when bonds are broken?
2. True or false: Thermal energy is the total potential and kinetic energy of the microscopic particles in an object.
3. What is a thermal insulator?
4. What are three types of heat transfer?
5. In what direction does heat flow?

2. 16.1 Thermal Energy and Matter
1. What is Temperature?
A measure of how hot or cold something is
Measured in Celsius, Fahrenheit, Kelvin

3. Related to the average kinetic energy
Related to the average kinetic energy (1/2mv2) of particles in an object (solid, liquid or gas), NOT the kinetic energy of the whole object
Card game

4. Depends on mass and temperature
2. What is Thermal Energy?
The total potential and kinetic energy of all the particles in an object
Depends on mass and temperature
Temp & Therm

5. Heat flows from hot to cold objects
3. What is Heat?
Transfer of thermal energy from one object to another due to a temperature difference
Heat flows from hot to cold objects
“when a group of fast-moving (warmer) molecules is placed next to a group of slow-moving (cooler) molecules, random collisions will cause the slower molecules to speed up and the faster ones to slow down, thus transferring energy from the warmer group to the cooler group”
4. Work and heat
Work creates heat through friction
Thermal paper

6. 5. What is Thermal Expansion?
As temperature increases, particles of matter move faster and further apart (more energy)
Thermal energy can do mechanical work
Some substances expand more than others
Thermometers use alcohol or mercury which expand a lot and expand consistently
Ball & loop, bimetallic wand, egg

7. Thermostats use bimetallic strips and “measure” the
Thermostats use bimetallic strips and “measure” the bend due to unequal expansion
As temperature decreases, particles of matter move slower and get closer together
Explain demos

8. Ex. Plastic vs. metal buckle on seat belt
6. What is Specific Heat?
The amount of heat needed to raise the temperature of one gram of material one degree Celsius
Objects with a low specific heat change in temperature MORE EASILY when given a certain amount of energy
Ex. Plastic vs. metal buckle on seat belt
Q = m x c x ∆T Q = thermal energy (J)
First 3 problems

9. 7. How do you measure heat changes?
Use a calorimeter
Thermal energy released by a test sample is equal to the thermal energy gained by surroundings.
Q(lost) = Q(gained)
Use surroundings whose specific heat is known (I.e. water)
msample x csample x ∆Tsample = mwater x cwater x ∆Twater
Next 2 problems, specific heat lab

10. 16.2 Heat and Thermodynamics
wand, balloon, ice, tea bag
16.2 Heat and Thermodynamics
1. How is thermal energy transferred?
A. Conduction
Transfer of thermal energy through collisions
Slow in gases because there are fewer collisions
Thermal conductor = a material that conducts thermal energy well (ex. Metals)
Thermal insulator = a material that doesn’t conduct thermal energy well (ex. air, wood)
Newton’s cradle, explain demos

11. When fluids heat, they expand, become less dense, and rise
B. Convection
Transfer of thermal energy when particles of a fluid (gas or liquid)move from one place to another
When fluids heat, they expand, become less dense, and rise
Convection currents are important in many natural cycles - ocean, weather, Earth’s interior
Explain demo

12. C. Radiation
Transfer of energy by waves moving through space, NO PARTICLES needed
The shorter the wavelength, the more energy
The radiation comes from vibrating electrons in every atom
All objects radiate energy

13. Radiation can be:
A. Absorbed: increasing the internal energy of the object (black vs. white color)
B. Reflected: bouncing off an object (shiny vs. dull)
C. Scattered: deflecting in all directions
D. Transmitted: going through an object (transparent vs. opaque)

14. Heat Transfer Activity, Greenhouse, Radiometer Challenge

15. 2. What is thermodynamics?
The study of conversions between thermal energy and other forms
A. First law of thermodynamics
Energy is conserved
B. Second law of thermodynamics
Disorder (entropy) naturally increases
Work must be done to make things orderly
Thermal energy flows naturally from hot to cold
Heat engine = any device that converts heat into work

16. Efficiency of an engine is less than 100%
Thermal energy that is not converted to work is called “waste heat”
C. Third law of thermodynamics
Absolute zero cannot be reached

17. 16.3 Using Heat

18. 1. What are two kinds of heat engines?
16.3 Using Heat
1. What are two kinds of heat engines?
A. External combustion engine
An engine that burns fuel outside the engine (ex. steam engine)
Hot steam enters the cylinder and pushes the piston down
Heat is converted to work
Some “waste” energy is lost due to friction, etc. The less waste energy, the more efficient the engine.

19. Basic steam engine components (locomotive… choo choo train)

20. B. Internal combustion engine
B. Internal combustion engine
An engine in which the fuel burns inside the engine (ex. Car)
Air and gas enters
Piston compresses
Spark plug ignites
Exhaust leaves

21. Turbine engine (internal combustion)
How a turbine works

22. Jet engine

23. Steam Power Plant

24. Steam Power Plant Use this to guide students. Solutions on next slides.

25. Steam Power Plant

26. Nuclear Reactor basics

27. 2. What are various heating systems?
Central heating heats many rooms from one central location
Use electricity, natural gas, oil, or coal
Vary in how the heat gets to the rooms
Use convection to distribute heat in the rooms
A. Hot-water heating
A boiler heats water
A pump carries the water to radiators
Radiators transfer heat to air by conduction and radiation
Hot air sets up a convection current in the room

28. B. Steam heating
Similar to hot water except steam is used
C. Electric baseboard heating
A coil of wire carries electricity
The heat of the coil heats air by conduction and radiation
Convection circulates the air through the room

29. D. Forced-air heating
Furnace burns oil or gas
Air is heated through conduction and radiation
Fans circulate warm air through ducts
Convection circulates air in each room

30. 3. How do cooling systems work?
Heat pumps reverse normal flow of thermal energy by using a refrigerant
Animation of a Heat PumpThe Heat Pump
A refrigerant absorbs heat and vaporizes (liquid to gas) then condenses (gas to liquid) and releases the heat elsewhere. Refrigerant are CONTAINED inside piping.

31. A. Refrigerator
A motor moves refrigerant through tubing inside refrigerator
The refrigerant removes heat from inside and vaporizes
The refrigerant moves to the coils outside the refrigerator
A pump pressurizes the refrigerant and forces it to condense, giving off the heat to the room

32. How A refrigerator works

33. B. Air Conditioner
Tubing with liquid refrigerant absorbs heat from the air in the room and vaporizes
The cool air is forced through the house
The vaporized refrigerant is pumped outside
A compressor forces the refrigerant to condense giving off heat to the outside