Thermal Energy
Physical Science
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Thermal Energy Objectives
1.
2.
3.
4.
Define temperature.
Explain how thermal energy depends on temperature.
Explain how thermal energy and heat are related.
Compare and contrast the transfer of energy by
conduction, convection, and radiation.
5. Compare and contrast thermal conductors and
insulators.
6. Explain how insulators are used to control the transfer
of thermal energy.
7. Understand the uses of thermal energy.
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Thermal Energy - Intro
1. What does the word thermal mean?
2. What are some words that contain thermal?
3. What is heat?
4. What are some things you do to make yourself
warmer or cooler?
5. Why do you think thermal energy in important?
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Thermal Energy - Demo
1. Write a paragraph describing which beaker do you
think the food coloring will spread the fastest.
Why?
2. Write a paragraph describing the results of the
demo. Infer why the food coloring spread through
the water in the two beakers at faster rates.
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Temperature and Heat – 6.1
A. temperature- related to the average kinetic energy of
an objects’ atoms or molecules
~as the temperature increases, the average speed of
the particles increase
~the SI unit is the kelvin, K
B. thermal energy (Q)- sum of the kinetic and potential
energy of all the atoms in an object.
1. Thermal energy increases as temperature increases
2. At constant temperature, thermal energy increases
if mass increases.
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Temperature and Heat
C. Thermal energy that flows from something at a
higher temperature to something at a lower temperature is
called heat
~ measured in Joules
Discussion
How do temperature and heat differ?
Answer
Heat is thermal energy that flows from a
warm object to a cool object.
Temperature is related to the kinetic
energy of atoms in an object.
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Write the question and the answer. Be sure to write the
heading.
Temperature and Heat- Review Questions
1. Explain how energy moves when you touch a block of
ice with your hand.
2. Describe how the thermal energy of an object changes
when the object’s temperature changes.
3. When heat flows between two objects, does the
temperature increase of one object always equal the
temperature of the other object? Explain.
4. Explain whether the following statement is true: for any
two objects, the one with the higher temperature always
has more thermal energy.
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Write the question and the answer. Be sure to write the
heading.
Temperature and Heat-Answers
1. Explain how energy moves when you touch a block of
ice with your hand.
TE transfers as particles in your hand strike particles of ice,
cooling off your hand and increasing the TE of the ice.
2.
Describe how the thermal energy of an object changes
when the object’s temperature changes.
Temp is avg KE of particles, as KE changes, TE changes
(decrease thermal energy = decrease in temperature)
3. When heat flows between two objects, does the
temperature increase of one object always equal the
temperature of the other object? Explain.
No. Not all thermal energy may have been transferred.
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Write the question and the answer. Be sure to write the
heading.
Temperature and Heat-Answers
4. Explain whether the following statement is true: for any
two objects, the one with the higher temperature always
has more thermal energy.
False. TE depends on the amount of material and the PE
of the particles of the objects.
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Transferring Thermal Energy
A. Conduction-transfer of thermal energy through matter
by direct contact of particles.
1. Kinetic energy is transferred as particles collide
2. Solids, particularly metals, are good heat
conductors.
~Faster moving
particles (greater KE)
transfer thermal
energy as they collide
with slower moving
(lower KE) particles
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Transferring Thermal Energy
B. The transfer of energy by the motion of heated
particles in a fluid is called convection.
1. Convection currents transfer heat from warmer to
cooler parts of a fluid.
2. Convection currents create rain forests and
deserts over different regions of the earth
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Transferring Thermal Energy
C. Radiation-energy transfer by electromagnetic waves
1. Some radiation is absorbed and
some is reflected when it strikes a
material
2. Heat transfer by radiation is
faster in a gas than in a liquid or
solid
~These waves can travel through
space.
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Transferring Thermal Energy
D. Most living things control the flow of heat by using
special features such as fur, blubber, or scales.
E. Insulator-material that does not let heat flow through
it easily.
1. Gases such as air usually make better insulators than
liquids or solids
~Since the gas molecules are so far apart, it is more
difficult for heat to be transferred
2. A vacuum layer in a thermos is a good insulator
because it contains almost no matter to allow
conduction or convection to occur.
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~Other good insulators-wood, some plastics, fiberglass
Transferring Thermal Energy
Discussion
What state of matter generally makes a good heat
conductor? Heat insulator?
Answer
Heat insulator-gases.
Heat conductor-solids, especially metals
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Write the question and the answer. Be sure to write the
heading.
Transferring Thermal Energy- Review Questions
1. Explain why materials that are good conductors of heat
are poor insulators.
2. Explain why the air temperature near the ceiling of a
room tends to be warmer than near the floor.
3. Predict whether plastic foam, which contains pockets of
air, would be a good conductor or a good insulator.
4. Describe how a convection current works.
5. Describe all the types of thermal energy transfer you
might experience when you go to the beach on a hot
summer day.
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Write the question and the answer. Be sure to write the
heading.
Transferring Thermal Energy- Review Answers
1. Explain why materials that are good conductors of heat
are poor insulators.
Heat passes easily through good conductors. They
increase the rate at which heat is transferred. A good
insulator decreases the rate at which heat is transferred.
2.
Explain why the air temperature near the ceiling of a
room tends to be warmer than near the floor.
Warm air rises because the faster moving particles
are farther apart making the air dense than the cool
air.
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Write the question and the answer. Be sure to write the
heading.
Transferring Thermal Energy- Review Answers
3. Predict whether plastic foam, which contains pockets of
air, would be a good conductor or a good insulator.
It would be a good insulator because the air pockets do not
easily transfer heat.
4. Describe how a convection current works.
Convection occurs when more energetic particles
move from one place to another. Convection currents
transfer heat from warmer to cooler parts of the fluid.
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Write the question and the answer. Be sure to write the
heading.
Transferring Thermal Energy- Review Answers
5.
Describe all the types of thermal energy transfer you
might experience when you go to the beach on a hot
summer day.
Conduction from hot sand/concrete, convection while in the
water, radiation from the sun
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Using Heat
A. Heating systems-warm homes and buildings.
1. forced-air system-fuel heats air, which is blown
through ducts and vents; cool air is returned to the
furnace to be reheated
2. radiator system-hot water or steam in a radiator
transfers thermal energy to the air
3. electric heating system-electrically heated coils in
ceilings or floors heats air by conduction
B. Solar energy -energy from the sun
1. passive solar heating does not use mechanical devices
to move heat
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2. Active solar heating systems use solar collectors to
absorb radiant energy, which is circulated through the
building.
C. Heat engine-an engine that converts thermal energy
into mechanical energy
1. An internal combustion engine burns fuel inside
the engine in chambers or cylinders.
2. Internal combustion engines convert only about 26%
of the fuel’s chemical energy into mechanical energy.
D. Heat mover-device that removes thermal energy from
one location and transfers it to another location at a
different temperature.
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1. A refrigerator contains a coolant that absorbs heat
from the inside of the refrigerator and releases it on
the outside as heat.
2. Air conditioners cool warm air.
3. Heat pumps can both cool and warm air.
4. The human body stays cool by evaporation and
sweat.
Discussion
What are the three types of heating systems?
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Using Heat Review Questions
1. How does the thermal energy of a closed system change
with time?
2. Compare and contrast an active solar heating system with
a radiator system.
3. How does an internal combustion engine work?
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Using Heat Review Questions-Answers
1. How does the thermal energy of a closed system change
with time?
-no heat flows across the boundary so the thermal energy
stays constant
2. Compare and contrast an active solar heating system with
a radiator system.
-both use hot water and radiators; in a radiator, fuel is
used to heat the water and in a solar heating system, the
sun’s rays (radiant energy) are used to heat the water
3. How does an internal combustion engine work?
-takes fuel into the combustion chamber and burns it to
convert chemical energy to mechanical energy
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