Transferring

Thermal Energy!

Conduction Transfer of thermal energy by direct

contact During collision, kinetic energy of faster

moving particle transferred to slower particle

Slower particle speeds up and faster particle slows down

Eventually temperature is the same everywhere

Heat Conductors Solids are the best conductors of

heat Particles are close together

Solid metals are very good conductors Move electrons easily Why are most cooking pots made of

metal (but the handles are not)?

Convection Transfer of energy in a fluid by

movement of the particles from one place to another

Movement is due to density Density = mass / volume As temperature increases, volume

increases, and density ?

Convection Currents Flow of material up from heated

area to cool area, then sink back down

Convection is very important to Earth’s climate

Atmospheric Circulation

Radiation Transfer of heat by

electromagnetic waves Electromagnetic waves are light Heat is radiated by infrared waves

Electromagnetic spectrum We can

measure wavelength and frequency of a wave

Wavelength: λ Frequency: f For any wave:

V= fλ

Electromagnetic Spectrum

Radiation When a wave strikes matter, some

is: Reflected (bounces off) Transmitted (passes through) Absorbed (taken in)

Controlling Heat Flow Insulators: Materials that do not

let heat move easily Some materials insulate from

convection, some from conduction, some from radiation

Good Insulators

Good Insulators