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GOALS
Explain molecular
motion as it relates to
thermal energy
changes in terms of
conduction,
convection, and
radiation.
Intro Clip
Differentiate
between
conduction,
convection, and
radiation.
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Temperature and Heat
• Temperature is the
measurement of the avg.
KE of the molecules in a
material.
• Heat is the transfer of
KE from one material to
another.
Clip
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THERMAL ENERGY TRANSFER
CONDUCTION CONVECTION RADIATION
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Conduction
•The transfer of thermal
energy in solids.
•Materials must be in
direct contact with each
other!
• Ex: Heating of the
bottom of a pot on stove.
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Convection
•clip
• Transfer of thermal energy
in liquids and gases.
• The matter
actually
moves from
one place
to another.
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Radiation
•Transfer of
thermal
energy by
electromagnetic waves (we’ll
discuses these more later)
• Transferring energy through
space...NO MATTER IS
REQUIRED!
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Clip
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Specific Heat
• Adding Energy to a material
Causes the
• Temperature to go up.
• Taking energy away from a
substance causes the temp. to
• Go down!
• Have you ever noticed that on a hot
summer day the pool is cooler than
the hot cement?
• OR maybe that the ocean is cooler
than the hot sand?
• Why? The sun has been beating
down on both of them for the same
amount of time...........
• It takes more thermal energy to
raise the temperature of water
that it does the cement!
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Water absorbs a lot of
heat energy before its
temperature changes
while sand needs little
heat energy before its
temperature increases.
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Specific Heat
• The amount of energy required
to raise the temperature of a
material (substance).
• It takes different amts of
energy to make the same temp
change in different substances.
• We call the amt required:
Specific Heat!
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Specific Heat of water
• The Cp is high because H2O
mols. form strong bonds
w/each other.
• It takes a lot of energy to
break the bonds so that the
the molecules can then start
to move around faster
(HEAT UP).
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Example:
Specific Heat of Water
• Cp = 4,184 Joules of energy
to raise the temperature
of 1kg 1°C.
Why Cp?
• video clip
Cp Stands for “Heat Capacity”
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Calculating Specific Heat
The Greek letter Δ means “change in”
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EXAMPLE : p162
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Mass = 45kg
Q = 203,000J
Δt = 40°-28°
Δt = 12°
Cp = ?
Q =m x Cp x Δt
Q/(m x Δt) = Cp
Cp = 376 J/(kg °C)
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Calorimeter
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Conduction can BEST be described as the transfer of
energy
A
B
C
D
by
by
by
by
traveling through space as waves
the movement of fluids
the expansion of gases
contact between particles
A copper ornament
has a mass of
0.0693 kg and
changes from a
temperature of
20.0°C to 27.4ºC.
How much heat
energy did it gain?
A 200 J
B 460 J
C 540 J
D 740 J
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