Transfer of Thermal Energy
HEAT ALWAYS FLOWS FROM HOTTER MATERIALS
TO COOLER MATERIALS, NEVER THE OTHER WAY!
*When warmer objects are put together with cooler
ones, the warmer objects lose heat and the cooler
ones gain heat until all the objects are at the same
* EXAMPLE OF HEAT
When you hold your hands around a mug of hot
chocolate, your body gets warmed. This happens
because heat flows from the hot mug into your skin.
Thermal energy is transferred from the cup to your
hands. Your body gains energy, and your
temperature rises as a result. Energy is lost from the
mug, however. It’s temperature decreases.
How does heat move?
Heat can move in three ways:
In conduction thermal energy flows through objects
as their particles vibrate.
It usually occurs in solids and between objects that
Example: Mug of hot chocolate to your hand.
A material through which heat can move easily is
called a conductor.
Iron, silver, aluminum, stainless steel, and copper
are all examples of metals that are good conductors.
A material that heat does not move through easily is
Plastic, wood, rubber, and glass are all good
Many cooking utensils and handles are made out of
plastic, wood, or rubber.
Some cooking pots are made of glass. Food will heat
more slowly than in a metal one, but it will stay hot
Other good insulators are leather and ceramics.
Air is a good insulator.
****It can help slow heat loss from a heated house to
the cold air outside. Fluffy material called insulation
is made up of many air spaces. When put inside
walls of a house, the insulation helps keep the house