HEAT / THERMAL ENERGY
Dec 31, 2015
HEAT / THERMAL ENERGY
Phase Changes
-Melting, Freezing, Evaporation, Boiling, Condensation, Sublimation
Temperature:
absolute zero: the temperature at which molecular motion stops.
the measure of the average kinetic energy of the particles in an object
http://www.brainpop.com/science/energy/temperature/
Heat
the energy transferred between objects that are at different temperatures
Heat is always transferred from the object that has the higher temperature to the object that has the lower temperature
http://www.brainpop.com/science/energy/heat/
When matter is heated, the molecules react by…..
-Speeding up
-Spreading out
Thermal: heat Expand: to get bigger
When matter is cooled, the molecules react by…..
-Slowing down
-Contracting
This is known as thermal expansion-The increase in volume (size) due to added heat.
Conduction
Transfer of heat / energy through direct contact
-Occurs best in solids
Conductors Insulators
Metal Objects
Water
Wood
Glass
Cotton
Rubber
Air
Convection
Transfer of heat / energy through liquids and gases
-Involves circular currents based on density of cooler / warmer matter
Radiation
Transfer of heat / energy through open space
-Radiate: To Give Off
Light Energy radiated from the sun
Only about half the energy from the sun reaches Earth. The other half is either reflected away or is absorbed by other factors
The Greenhouse Effect
Warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth
OZONE
Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere).
Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation.
Pollution is depleting it – upsetting the natural balance of “good” ozone at the stratospheric level of the atmosphere
Brainpop greenhouse effect