Thermal Energy and Heat

Temperature

The measure of how HOT or COLD and object is.

Temperature

Related to the AVERAGE KINETIC ENERGY of the particles of an object.

How temperature changes

As an object heats up, its particles move faster. As a result the average kinetic energy

increases and ……. The temperature increases.

Kinetic energyTemperature

Sand in the cup demo

Thermal Energy

The total energy of all of the atoms and molecules in a substance.

Thermal Energy

Depends on:MASSTEMPERATURE

Demo: nuts and bolts in water

Which has more thermal energy…

…A cup of coffee or a pot of coffee?

Which has more thermal energy…

…A cup of coffee or a pot of coffee?

THE POT OF COFFEE

WHY???

Which has more thermal energy…

…A cup of coffee or a pot of coffee?

THE POT OF COFFEE

WHY???It has more MASS.

Which has more thermal energy…..

A cup of hot tea or a cup of iced tea?

Which has more thermal energy…..

A cup of hot tea or a cup of iced tea?

The cup of HOT tea.WHY?

Which has more thermal energy…..

A cup of hot tea or a cup of iced tea?

The cup of HOT tea.WHY?

It is at a higher TEMPERATURE.

HEAT

The transfer of thermal energy from one object to another because of a temperature difference.

Thermal energy ALWAYS flows from WARMER to COLDER.

3 Ways heat is transferred

ConductionConvectionRadiation

CONDUCTION

The transfer of thermal energy in materials that are touching.

Occurs as particles collide

Conduction

Involves no overall transfer of matter Takes place more easily in solids than in

liquids or gases.

Conduction

Conductors

Objects that conduct thermal energy well.

Insulators

Poor conductors of heat Examples:

Insulators

Insulators

Why do tile floors feel colder than wooden floors?

Why does your tongue stick to a pole on a freezing cold day?

Convection

The transfer of thermal energy by the movement of FLUIDS with different temperatures.

Convection Current

When you heat up a liquid or gas the molecules move faster, and spread out and become less dense.

Since it is less dense it rises. After it rises, it is away from the heat source

and cools. Once it is cool, it sinks.

Convection Current

Convection Currents

Convection currents

Home heating and convection currents

Radiation

The transfer of thermal energy by electromagnetic waves traveling through space.

Radiation

Does NOT involve the movement of particles. Is the only form of transfer of thermal energy

that can occur in space.

Radiation

Shiny objects reflect electromagnetic energy

Dull, dark objects absorb electromagnetic energy

Absorbed electromagnetic energy is converted into thermal energy.

Radiation

Radiation