Post on 21-Jan-2016
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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