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Objectives |
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Essential Question:
In all of human knowledge, outside
of religion, what comes closest to absolute truth? |
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Thermodynamic Systems and Concepts
Note: Here thermodynamic
systems assumes a fixed mass of an ideal gas.
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Explain what is meant by
thermodynamic system. Example: expansion and compression of an ideal gas .
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Describe the concepts
heat, work and internal energy.
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Deduce an expression for
the work involved in a volume change of a gas at constant pressure.
Processes
The 1st Law of
Thermodynamics
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State the
1st law of
thermodynamics.
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Describe the isochoric (isovolumetric),
isobaric, isothermal and adiabatic processes. (The heat transferred, the
work done and internal energy change should be addressed. The ideal gas
equation of state should be applied to all processes except the adiabatic.)
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Draw and annotate
thermodynamic processes and cycles on p-V diagrams.
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Calculate the work done in
a thermodynamic cycle from a p-V diagram. (Hint: It's area under the
curve.)
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Solve problems involving
state changes of a gas.
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Lesson 1
Essential Question:
Key Concept: The 1st
law of Thermodynamics.
Purpose: Show how
the first law in combination with perfect gas laws can be used to
evaluate idealized processes.
Discussion questions:
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In all of science, what principle
comes closest to absolute truth?
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Bob has a solar panel covering 2
square meters. He buys a lens with the same area and uses it to
focus the sun's light on a smaller panel with 0.2 square meters. Will he improve the electrical output from his solar cell
system using the lens. (assume solar cell efficiency remains
constant with temperature.)
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Why is hydrogen not a true energy
source?
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Does a ceiling fan heat or cool a
room?
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Heat
engines and heat pumps
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Outline the concept of the
heat engine and the heat pump.
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Draw and annotate
schematic diagrams of a heat engine and a heat pump.
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Define the term
thermal
efficiency of a heat engine 2 ways, mathematically and in English language.
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Draw and annotate the
Carnot cycle on a p-V diagram.
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State what the Carnot
Cylce represents.
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State Carnot’s theorem.
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State an expression for
the efficiency of a Carnot engine in terms of the temperatures of the two
reservoirs.
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Discuss the possibility of
changing the thermal efficiency by altering the reservoir temperatures.
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Solve problems involving
heat engines and heat pumps.
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Lesson 2 Essential Question:
Could the engine in a car convert 100% of the energy in the gasoline
it burns into usable work?
Key Concept:
Introduce the basics required for evaluating new energy related
inventions.
Discussion questions:
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Would a friction free engine in a car be able to
convert 100% of the energy in gasoline into useful work?
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Will a heat pump work as
well in Minnesota as in Greenville SC?
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Second Law
of Thermodynamics and Entropy
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State that heat can be
completely converted to work in a single process, but that continuous
conversion of heat into work requires a cyclical process and the rejection of
some heat.
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State the Kelvin–Planck
formulation of the
2nd law of thermodynamics.
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It is sufficient for
students to acknowledge the impossibility of constructing a heat engine
operating in a cycle that does not transfer energy to a cold reservoir.
Teachers might like to show that if this were possible then it would imply
that energy can be transferred spontaneously from a cold to a hot reservoir.
This leads to the Clausius statement of the 2nd law.
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Analyze situations in
terms of whether they are consistent with the first and/or second law.
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State that entropy is a
system property that expresses the degree of disorder in the system.
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State the second law in
terms of entropy changes. A statement that the overall entropy of the
universe is increasing will suffice.
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Discuss examples of
natural processes in terms of entropy changes.
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Students should understand
that although local entropy can decrease, any process will increase the total
entropy of the system and surroundings.
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Discuss the idea of energy
degradation in terms of the second law.
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Be as one with the relevant equations
HL thermodynamics
equations in the IB Physics Data Booklet.
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Lesson 3 Essential Question:
Is the universe winding down?
Key Concept: The 2nd
Law of Thermo and entropy
Purpose:
Introduce the basics required for evaluating new energy related
inventions.
Discussion questions:
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Does the 2nd Law of Thermo
preclude the possibility of biological evolution?
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