1. Heat and Temperature

2. What is Heat?? Heat = Thermal Energy!!
Thermal Energy = the total energy of all of the particles in a material or object.
Throughout the ages people have invented a variety of devices to help create and capture heat for use.

3. Topic 1: Using Energy from Heat
What are some ways that we use heat?
Cook food
Warm buildings
Dry clothes
What are some ways Thermal Energy has been used throughout history?

4. Devices to generate, transfer, control or remove heat
Heat = Thermal energy
Can you think of any examples of devices that generate, transfer, control or remove heat?

5. Topic 2: Measuring Temperature
Thermometer: Mechanical or electrical device for measuring temperature. Early thermometer was invented by Galileo.
Scale: A series of equally measured sections that are marked and numbered for use in measurement.

6. Celsius Scale
Celsius Scale: Most commonly used in Canada. Unit of temperature is called a degree. Based on the boiling and freezing points of water.
Boiling Point: The temperature at which water boils. 100o C at sea level.
Freezing Point: The temperature at which water freezes. 0o C at sea level.

7. Another Scale… Kelvin is another way of measuring temperature.
Scientists use Kelvin to explain the behaviour of gases.
“Absolute Zero” is measured in Kelvin – which is the coldest possible temperature
0 Kelvin = -273 ºC

8. Bimetallic Strip Made of two different metals joined together
When the strip is heated one metal expands more than the other
Thus the strip coils more tightly
Movement of the strip can operate a switch that can control furnaces…commonly used in thermostats in homes

9. Your Brain…(extra) Your brain has its own temperature sensor.
It monitors your own internal temperature. If the temperature outside changes, the sensor signals your brain to release chemicals that will help your body adjust to normal temperature (37°C)

10. Continued
Recording Thermometer: A bimetallic strip connected to a writing device and paper which records temperature fluctuations over time.
Infrared Thermogram: Records infrared radiation, (heat sensor) as different colors according to their temperature.

11. Topic 3: Particle Model of Matter, Temperature and Thermal Energy
Reminder: matter is anything that takes up space
Three most important ideas of the model:
All substances are made of particles too small to see
The particles are always in motion
The particles have space between them

12. When motion of particles increases – so does the temperature
When motion of particles decreases – so does the temperature
Temperature indicates the average speed of particle motion in a substance

13. Energy
Energy is the ability to do work – in other words to cause change
In order for something to change, there must be a transfer of energy from one thing to another
Ex. Charged batteries run your iPod, dead batteries would not

14. First Law of Thermodynamics
Says there are two ways to increase temperature:
Increase the thermal energy in the system
Do work to that system
Example: pushing a couch

15. Second Law of Thermodynamics
Thermal energy spontaneously spreads from regions of high concentration to areas of low concentration.
Basically heat moves to cold places.

16. Entropy The the measure of randomness in a system.
A lot of energy goes into a system, but very little energy comes out, it is transferred chaotically.
Example: building a house of cards

17. What Energy is…and is not
Energy is not a substance.
It cannot be weighed
It does not take up space
Energy describes a condition
Law of Conservation of Energy: Energy cannot be created or destroyed. It can only be transformed from one type to another or passed from one object to another

18. Temperature vs. Thermal Energy
Temperature = A measure of the average energy of the particles in a material.
Thermal Energy = The total energy of all the particles in a material.
What is the difference??

19. Topic 4: Expansion and Contraction
Contract: Decrease in volume
Expand: Increase in volume
Temperature changes cause things to expand and contract
Heated – usually causes expansion
Cooled – usually causes contraction
Usually more drastic in gases, then liquids then solids

20. Specific Heat Capacity
Amount of thermal energy that warms or cools one gram of a material by one degree Celsius.

21. Sample Specific Heat Capacity Table

22. Solids Solids have definite shape and volume
Cannot be compressed into smaller objects
When solids are heated – they expand
When solids are cooled – they contract

23. Liquids Liquids have definite volume but no shape
Cannot be compressed (meaning if I have 1 litre of coke, I cannot make it fit into a pop can)
When liquids are heated – they expand
When liquids are cooled – they contract

24. Gases Have no definite shape or size Can be compressed
When heated, gases – expand
When cooled, gases - contract

25. Changes of State

26. Definitions: Define, in your notes, each of the following: Melt Freeze
Evaporate
Condense
Sublimation

27. Continued
Evaporative Cooling: A process in which the faster moving particles on the surface of a liquid evaporate and escape into the air, the slower ones are left behind creating a lower average kinetic energy (cooling it)
Particles are more or less organized when they are hot or cold????

28. Phase Changing
During a change from solid to liquid or liquid to gas the average temperature does not change even though heat is being added, the name for the heat that is added is latent heat.

29. Radiant Energy
All forms of radiant energy share several characteristics:
- They behave like waves
- They can be absorbed and reflected by objects
- They travel across empty space at the same high speed of 300,000 km/s

30. Topic 7: Sources of Thermal Energy
Energy appears in many forms
Potential Energy: Stored energy
E.g. elastic pulled back and ready to be shot.
Kinetic Energy: Energy of motion
Examples??

31. Chemical Energy
Stored chemical energy is released in the form of thermal energy when it is burned.

32. Electrical Energy Electricity
Example: hydro-electric dams – falling water is changed to electrical energy

33. Geothermal Energy
Energy that we get from the Earth’s interior

34. Solar Energy
Energy from the sun

35. Passive Solar Heating
Uses materials in the structure to absorb, store, and release solar energy.
Example: a wall of windows

36. Active Solar Energy
Uses mechanical devices to distribute stored thermal energy
Example: fans
Solar Collectors – use stored water or air on the roof, heats it, and then pumps it through the building

37. Wind Energy
Moving air
Is a result of solar energy – as the sun heats the air, the warmer air rises and cools off. Cooler air falls, creating a convection current – this forms wind

38. Fossil Fuels
Chemicals made from plants and animals that died and decomposed millions of years ago and have preserved deep underground.

39. Energy Converters Energy can be converted into another form.
For example a candle can convert chemical energy into heat and light energy.
Candles are energy converters (devices which convert or change energy from one form to another.)
Other examples????