THERMAL ENERGY

TRANSFERSChapter 6 Lessons 1 and 2

THERMAL ENERGY AND TEMPERATURE Thermal Energy

Sum of the kinetic energy and the potential energy of the particles that make up a material

TemperatureAverage kinetic energy of the particles that

make up a material

THERMAL ENERGY AND TEMPERATURE CONTINUED Temperature and thermal energy are not

the same!Similar kinetic energy (ice melting)Different potential energy (distance

between particles)

HEAT Movement of thermal energy from a

warmer object to a cooler object

Heat and thermal energy are not the same.All objects have thermal energy.When you heat an object, thermal energy is

transferred.

HOW IS THERMAL

ENERGY TRANSFERRED?

Radiation, Conduction, Convection

RADIATION The transfer of thermal energy from one

material to another by electromagnetic wavesWarm objects: more radiationCan be transferred through solids, liquids,

and gasesOnly way thermal energy can travel from

Sun to EarthSpace is a vacuum.

RADIATION CONTINUED How does the Sun heat the inside of a

car?

Jumping Penny Demo

CONDUCTION Transfer of thermal energy between

materials by the collision of particles (contact)Continues until all particles in contact are

equal Thermal conductors

A material through which thermal energy flows easily Metals

Thermal insulatorsMaterial through which thermal energy does

not flow easily

CONDUCTION CONTINUED Specific Heat

The amount of thermal energy required to increase the temperature of 1 kg of material by 1C

Thermal conductors have a lower specific heat

Thermal insulators have a higher specific heat

Water has a high specific heat Prevents body from overheating Used to cool machinery Pools, oceans, lakes cool in summer

THERMAL EXPANSION AND CONTRACTION Thermal Expansion

An increase in a material’s volume when its temperature increases Particles speed up and move farther apart

Thermal ContractionA decrease in a material’s volume when its

temperature decreases Particles slow down and move closer together

Most noticeable in gases, less in liquids, and least in solids

THERMAL EXPANSION AND CONTRACTION CONTINUED Sidewalk Gaps

Too much expansion causes cracksControl joints cut for cracks

Hot Air BalloonsThermal Expansion – to riseThermal Contraction – to land

Ovenproof GlassExpands less than ordinary glass

CONVECTION Warm liquid moves from one place to

another, which transfers thermal energy Only occurs in fluids (water, air, magma,

syrup)

DENSITY, THERMAL EXPANSION, THERMAL CONTRACTION Heating water:

Burner transfers thermal energy to the container

Thermal expansion in water in the bottom makes it less dense

Water surface transfers thermal energy to air

Water on surface cools and contractsDense water sinks to the bottomLess dense water risesCycle continues

CONVECTION CURRENTS IN EARTH’S ATMOSPHERE Convection Current: movement of fluids in

a cycle because of convectionCirculates water on Earth, air in a room,

materials in Earth’s interior, Moves matter and thermal energy from inside

the Sun to its surface Move air between the equator and

latitudes 30N and 30S Earth’s climatesSun’s thermal energy is concentrated in this

areaHeat moves from warmer objects to cooler

objects