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Unit 13: Thermodynamics Page 18
higher temperature object slow Heat transferred from one object to
down and the movement of the another through conduction does
molecules in the lower temperature the same thing. The molecules
object speed up. near the heat source (candle,
stove, etc.) begin moving faster
In our example of the ice and the
(their temperature increases).
lemonade, it would work like this.
The lemonade has a higher As they move faster they crash
temperature than the ice. (The into other molecules around them
molecules are moving faster than which cause them to move faster.
the ice molecules.) As those molecules move faster
they crash into more
The faster moving molecules of the
molecules...etc, etc. Thus the
lemonade would transfer heat to
molecules in the object are all
the ice causing the ice molecules to
moving faster.
move faster (increase
temperature) and eventually Heat has been transferred by
change from solid to liquid. conduction and the temperature of
the object is higher. This
In turn, since the faster moving
experiment may make this clearer.
molecules of the lemonade moves
energy (transfers heat) to the ice,
Radiation
they slow down. This causes the
temperature of your drink to Heat is transferred by radiation
decrease and that is what makes through electromagnetic waves.
your lemonade nice and cold. Heat Remember, when we talked about
can be transferred in three waves and energy in Unit 9? Well,
different ways: conduction, heat can be transferred by
convection and radiation. electromagnetic waves.
Energy is vibrating particles that
Conduction
can move by waves over distances
Let’s start with conduction. Heat is right? Well, if those vibrating
transferred through conduction the particles hit something and cause
same way pool balls are scattered those particles to vibrate (causing
around a table in the opening them to move faster/increasing
break. On a pool table, one ball their temperature) then heat is
crashes into another ball which being transferred by waves.
crashes into another ball speeding
The type of electromagnetic wave
the balls up and moving them
that transfer heat are infra-red (IR)
around the table.
waves. The Sun transfers heat to
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