1. Temperature and Heat

2. What is Temperature?
Measurement of the average Kinetic Energy (KE) of the molecules.
Lots of KE=high temperature
Low KE = low temperature
Expansion vs. Contraction
Hot objects expand because of high KE.
Cold objects contract because of low KE.

3. Thermal Energy
The sum of the KE and PE of all the molecules in an object.
Also increases with temperature
If temperature is constant and mass increases so does the thermal energy.

4. Always flows from Hot to Cold no matter what.
Heat Energy
Transfer of energy from the particles of one object to another because of temperature differences.
Always flows from Hot to Cold.
Stops transfer when equilibrium is reached.
Examples
Ice in your hand
Touch a hot pan
Air conditioning on your skin
Always flows from Hot to Cold no matter what.

5. Energy Transfer: Conduction
Transfer energy from direct contact between objects or particles.
Collisions between molecules changing their KE and PE.
Works best when a solid is involved

6. Convection
Transfer of energy by the movement of fluids with different temperatures.
Fluid moves as its density changes.
High temp. = low density
Low temp. = high density
Only works for fluids
Gas
Liquid

7. Radiation Transfer of energy by electromagnetic waves
Light UV
X-ray
Infared
Microwaves
Doesn’t need matter to transfer heat.

9. Conductors vs. Insulators
Material that easily transfers energy
Metal
Dark colors
Insulators
Material that is a poor conductor of energy
Wood
Glass
Plastic
Rubber

10. Did you know?
The avg. amount of solar energy that reaches the U.S. each year is about 600x greater than our annual demands for energy.
Lightning heats air to 25,000°C. 4x the surface of the sun.
Without the sun our average temp. would be –240 °C.
More than 70% of the energy you use at home is for maintaining temperature from refrigerators to a/c.