Physics 7A DL 7 Overview DL 7
Brief Overview
The first Activity reviewing the FNTs from the previous DL provides you a chance to make sure you
comfortable working with both forms of the energy conservation equations (sum of changes and energy
totals) as well as graphing energy changes as a function of the position variable in the potential energy.
The second and third Activities introduce new concepts and ideas: the very important relationship between
force and potential energy and the physical model of two masses connected by a spring that describes
interactions between neutral atoms or molecules.
Activities
Activity 2.9 Follow-up of FNTs
Purpose:
• To make sure you are able to apply the Energy-Interaction Model to various mechanical and
combined mechanical and thermal systems.
• Confident in graphing energies as a function of the position variable in the PE.
• Confident is constructing scientific explanations based on the Energy-Interaction Model.
Learning Outcomes:
• FNT 1: Ability to accurately use the energy-interaction model to obtain numerical predictions for
more complicated mass-spring situations.
• FNT 2: Ability to reason with the Energy-Interaction Model with combined mechanical and
thermal systems.
• FNT 3: Ability to accurately graph energies as a function of the position variable. Develop better
understanding of the graphical representation of energy relationships: 𝐸𝑡𝑜𝑡𝑎𝑙 = ∑ 𝐸 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡.
• Ability to use the “total energy stays constant” approach in mechanical systems.
• Ability to develop solid, logical explanations based on the “givens” in the physical situation and
the relationships of the Energy-Interaction Model.
Activity 2.10 The Connection between Force and Potential Energy
Purpose:
To introduce the relationship of force to potential energy.
Learning Outcomes:
• Achieve understanding of the connection between the force acting on a mass and the shape of
the gravitational potential energy vs. position curve for that mass.
• Ability to predict the force acting on a mass from knowledge of the spring-mass potential
energy curve vs. position curve for that mass.
• Develop a general relationship for the direction and magnitude of force and potential energy,
𝑑(𝑃𝐸)
mathematically written as 𝐹𝑥 = − .
𝑑𝑥
•
Activity 2.11 A New Physical Situation: Two Masses connected by a Spring
Purpose:
• Describe the interaction between two neutral atoms or molecules.
• Create a potential energy for the pairwise atomic interaction (known as the Lennard-Jones
potential) starting with a simple model of two particles attached by a spring.
Learning Outcomes:
• Be familiar with the general shape of the Lennard-Jones potential (𝑃𝐸𝐿𝐽 ).
• Ability to describe (direction and relative magnitude) the force acting between two masses
subject to a LJ potential energy.
Unit 2: Applying Models to Mechanical Phenomena DL 7
, Physics 7A Activity 2.9 DL 7
Follow-up of FNTs
FNT 1 (all groups):
Put your response for this FNT on the board. Make sure to outline both methods as described in parts b)
and c).
Whole Class Discussion
Groups 1, 2, and 3 discuss and respond to FNT 2 as directed below.
Groups 3, 4, and 6 discuss and respond to FNT 3 as directed below.
FNT 2:
1) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part a)
of this FNT.
2) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part b)
of this FNT.
FNT 3:
1) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part a)
of this FNT. How is your diagram different for part b) of this FNT?
2) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part c)
of this FNT. Could you have used different interval to answer the same question? Briefly show/explain
on the board.
Whole Class Discussion
FNT 4 (all groups):
1) Copy the figure and chart provided on your board. Knowing that the slope is frictionless, draw the E th
curve for the 1st part of the process. Now explain how you determine the total energy and plot Etotal.
2) Which energies change on the slope? Which energies change on the horizontal plane? Plot all
remaining energy curves for the whole processes.
Whole Class Discussion
Unit 2: Applying Models to Mechanical Phenomena DL 7
Brief Overview
The first Activity reviewing the FNTs from the previous DL provides you a chance to make sure you
comfortable working with both forms of the energy conservation equations (sum of changes and energy
totals) as well as graphing energy changes as a function of the position variable in the potential energy.
The second and third Activities introduce new concepts and ideas: the very important relationship between
force and potential energy and the physical model of two masses connected by a spring that describes
interactions between neutral atoms or molecules.
Activities
Activity 2.9 Follow-up of FNTs
Purpose:
• To make sure you are able to apply the Energy-Interaction Model to various mechanical and
combined mechanical and thermal systems.
• Confident in graphing energies as a function of the position variable in the PE.
• Confident is constructing scientific explanations based on the Energy-Interaction Model.
Learning Outcomes:
• FNT 1: Ability to accurately use the energy-interaction model to obtain numerical predictions for
more complicated mass-spring situations.
• FNT 2: Ability to reason with the Energy-Interaction Model with combined mechanical and
thermal systems.
• FNT 3: Ability to accurately graph energies as a function of the position variable. Develop better
understanding of the graphical representation of energy relationships: 𝐸𝑡𝑜𝑡𝑎𝑙 = ∑ 𝐸 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡.
• Ability to use the “total energy stays constant” approach in mechanical systems.
• Ability to develop solid, logical explanations based on the “givens” in the physical situation and
the relationships of the Energy-Interaction Model.
Activity 2.10 The Connection between Force and Potential Energy
Purpose:
To introduce the relationship of force to potential energy.
Learning Outcomes:
• Achieve understanding of the connection between the force acting on a mass and the shape of
the gravitational potential energy vs. position curve for that mass.
• Ability to predict the force acting on a mass from knowledge of the spring-mass potential
energy curve vs. position curve for that mass.
• Develop a general relationship for the direction and magnitude of force and potential energy,
𝑑(𝑃𝐸)
mathematically written as 𝐹𝑥 = − .
𝑑𝑥
•
Activity 2.11 A New Physical Situation: Two Masses connected by a Spring
Purpose:
• Describe the interaction between two neutral atoms or molecules.
• Create a potential energy for the pairwise atomic interaction (known as the Lennard-Jones
potential) starting with a simple model of two particles attached by a spring.
Learning Outcomes:
• Be familiar with the general shape of the Lennard-Jones potential (𝑃𝐸𝐿𝐽 ).
• Ability to describe (direction and relative magnitude) the force acting between two masses
subject to a LJ potential energy.
Unit 2: Applying Models to Mechanical Phenomena DL 7
, Physics 7A Activity 2.9 DL 7
Follow-up of FNTs
FNT 1 (all groups):
Put your response for this FNT on the board. Make sure to outline both methods as described in parts b)
and c).
Whole Class Discussion
Groups 1, 2, and 3 discuss and respond to FNT 2 as directed below.
Groups 3, 4, and 6 discuss and respond to FNT 3 as directed below.
FNT 2:
1) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part a)
of this FNT.
2) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part b)
of this FNT.
FNT 3:
1) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part a)
of this FNT. How is your diagram different for part b) of this FNT?
2) Construct a complete Energy-Interaction diagram with accompanying equations as directed in part c)
of this FNT. Could you have used different interval to answer the same question? Briefly show/explain
on the board.
Whole Class Discussion
FNT 4 (all groups):
1) Copy the figure and chart provided on your board. Knowing that the slope is frictionless, draw the E th
curve for the 1st part of the process. Now explain how you determine the total energy and plot Etotal.
2) Which energies change on the slope? Which energies change on the horizontal plane? Plot all
remaining energy curves for the whole processes.
Whole Class Discussion
Unit 2: Applying Models to Mechanical Phenomena DL 7
