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Unit 13: Thermodynamics Page 17
relatively easily at room really not what heat is as far as
temperatures. physics goes.
And, believe it or not, solids can Heat, in a way, doesn’t exist.
change to liquids and even gases Nothing has heat. Things can have
and vice versa at temperatures a temperature. They can have a
other than the usual melting, thermal energy but they can’t have
freezing, or boiling points. So heat. Heat is really the transfer
what’s the point of the points? of thermal energy. Or, in other
words, the movement of thermal
At a substance’s boiling, freezing,
energy from one object to another.
etc, points, all of the substance
must change to the next state. The If you put an ice cube in a glass of
condition of the bonds cannot lemonade, the ice cube melts. The
remain the same at that thermal energy from your
temperature. For example, at 100° lemonade moves to the ice cube.
C water must change from a liquid Increasing the temperature of the
to a gas. That is the speed limit of ice cube and decreasing the
liquid water molecules. At 100° C temperature of your lemonade.
the liquid bonds can no longer hold
The movement of thermal energy
on and all the molecules convert to
is called heat. The ice cube
gas.
receives heat from your lemonade.
Your lemonade gives heat to the
Heat Transfer
ice cube.
The heat is on! Now we are going
Heat can only move from an object
to learn what heat is and how it
of higher temperature to an object
moves from place to place. You
of lower temperature. Heat goes
know how they say, “If you can’t
from hot to cold. Coffee cools
stand the heat, get out of the
down and ice water heats up.
kitchen.”?
That’s one of the laws of
Well after this lesson you’ll know thermodynamics.
exactly what it is that you can’t
Do you remember what
stand!
temperature is? Temperature
Heat measures how fast molecules are
moving, right?
Believe it or not, the concept of
Well, when heat transfers (moves)
heat is really a bit tricky. What we
from one object to another, the
call heat in common language, is
movement of the molecules in the
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