Thermal Energy

Heat

Thermal Energy

Thermal Energy

• The total energy of all the particles in an object

• Depends on……– temperature of the object– # of particles in the object– the arrangement of the particles in the object

Temperature

• Measure of average kinetic energy of the particles

• F- boiling = 212 - freezing = 32

• C- boiling = 100-freezing = 0

Kelvin- boiling = 373 - freezing =

273Absolute zero = -273 Celsius

Heat

• The transfer of thermal energy is heat.• Moves from a warmer object to a cooler

object

• Specific Heat – the amount of energy required to raise the temperature of 1 kilogram of a material by 1 Kelvin. (in Joules)

Heat

The flow of thermal energy from one object to another.

Heat always flows from warmer to cooler objects.

Ice gets warmer while

hand gets cooler

Cup gets cooler while hand gets

warmer

Specific Heat

• Materials with high Specific Heat can absorb a great deal of energy without a great change in temperature.

• Ex: Water requires 4,180 joules to raise the temperature 1 degree Kelvin.

Specific Heat

Some things heat up or cool down faster than others.

Land heats up and cools down faster than water

Why does water have such a high specific heat?

Water molecules form strong bonds with each other; therefore it takes more heat

energy to break them. Metals have weak bonds and do not need as much energy to

break them.

water metal

Heat Transfers

• Conduction- heat transferred through direct touch

• Convection- heat transferred through the movement of currents in a fluid

• Radiation- heat transferred through electromagnetic waves

Heat Transfers

Conductors and Insulators

• Conductor- transfers thermal energy well• Ex: metals

• Insulators- transfers thermal energy very poorly

• Ex: Wood, paper, plastic, gases in the air

Changes in State of Matter

• Depends on how much thermal energy • Vaporization- matter changes from liquid to a

gas• Evaporation- vaporization at the surface• Boiling- vaporization below the surface• Melting- solid to liquid• Freezing- liquid to solid• Condensation- gas to liquid