Heat & Heat TechnologyChapter 13

Temperature Measure of the average kinetic energy of the

particles in an object Same average kinetic energy = equal temperature

Thermal expansion Increase in volume of a substance

because of an increase in temperature

Absolute zero The lowest temperature on the Kelvin

scale 0 K (about -273.16°C) Temperature where all molecular motion

stops Not possible to reach it

Converting temperaturesCelsius to Fahrenheit°F = (9/5 x °C) + 32

Fahrenheit to Celsius°C = 5/9 x (°F – 32)

Celsius to KelvinK = °C + 273

Kelvin to Celsius°C = K – 273

Freezing point of water32° F0° C

273 K

Heat The energy transferred between objects

that are at different temperatures

Thermal energy The total kinetic energy of the particles

that make up a substance Measured in joules (J)

Thermal conduction The transfer of thermal energy from one

substance to another through a material or direct contact

Thermal conductors A material through which energy can be

transferred as heat Example: metals

Curling iron Cookie sheet Iron skillet Copper pipe Stove coil

Thermal insulators A material that reduces or prevents the

transfer of heat Examples

Flannel shirt Oven mitt Plastic spatula Fiberglass insulation Ceramic bowl

Convection Transfer of thermal energy by the circulation or

movement of a liquid or a gas Convection causes the repeated rising and

sinking of water during boiling Wind is a result of earth heating by sun

Radiation Transfer of energy by electromagnetic

waves like in visible light or infrared waves

Specific heat Amount of energy needed to change the

temperature of 1 kg of a substance by 1°C

States of matter The physical forms in which a substance

can exist Particles move at different speeds The “state” of a substance depends on

Particle speed (kinetic energy) Attraction between particles (potential

energy) Pressure around particles

3 familiar states of matter Solid Liquid Gas

Change of state A change of a substance from one state

of matter to another Physical change only

Just affects physical properties but NOT the identity of the substance (i.e. water is still water whether it is a solid, liquid, or a gas)

Changes of state

• Freezing: liquid to solid• Melting: solid to liquid• Boiling: liquid to gas• Condensing: gas to liquid

Insulation Material that reduces the transfer of

thermal energy (i.e. less heat passes into or out of)

Used in walls, ceilings, and floors Helps houses stay warm in the winter Helps houses stay cool in the summer

Heat engine Machine that uses heat to do work Fuel combines with oxygen (O2 ) in a

chemical change that releases thermal energy

Thermal pollution Excessive heating of a body of water

caused by human activity Happens with large power plants that

are near bodies of water Harms animals living in water