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Thermal Physics
The Kinetic Theory of
Matter
The zeroth law of thermodynamics gives us a
macroscopic
(large scale) definition of the concept of the temperature of
a body. The kinetic theory of matter can be used to give a
microscopic
definition of temperature.
The basic ideas of the kinetic
theory are
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i) |
all matter consists
of particles (atoms or molecules) in motion |
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ii) |
as the temperature
increases, the average speed of the movement increases. |
According to this theory, the temperature
of a body is a measure of the
average kinetic energy
of it particles.
This theory can also be used to explain the differences
between the different
states (or phases) of matter.
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Solids |
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The particles
vibrate around
fixed positions.
They are close together and so attract each other
strongly. This is why solids maintain their shape. |
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Liquids |
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The particles are
still relatively close together but now have
enough energy to
"change places" with each other.
This is why liquids can
flow. |
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Gases |
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Average distance between particles
typically
10 times greater
than in solids and liquids. The particles now move
freely at random,
occupying all the space available to them.
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Links to:
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The
Open Door Web Site