PS3.B (C) - Objects in Contact - FINAL (CLF 1/28/2014)

Module: Objects in Contact

DCI: PS3.B (C) When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object.

PE: MS-PS3-2 Develop a model to describe that when the arrangement of objects interacting at a distance changes, different amounts of potential energy are stored in the system.

 [Clarification Statement: Emphasis is on relative amounts of potential energy, not on calculations of potential energy. Examples of objects within systems interacting at varying distances could include: the Earth and either a roller coaster cart at varying positions on a hill or objects at varying heights on shelves, changing the direction/orientation of a magnet, and a balloon with static electrical charge being brought closer to a classmate’s hair. Examples of models could include representations, diagrams, pictures, and written descriptions of systems.] [Assessment Boundary: Assessment is limited to two objects and electric, magnetic, and gravitational interactions.]

The ideas in this standard are: 

- any time two objects interact, one exerts a force on another and energy can be transferred to or from the object. 

When they talk about developing a model, this can be a conceptualization of the fact that potential energy changes as distance between objects changes. (Gravitational potential energy increases as objects get higher away from the Earth's surface, or the example of a charged balloon moving closer to someone's hair...) These examples help us to see that what they want students to know is that the potential energy between two objects changes as the distance between them changes. 

We have a batch similar to this in high school that focuses on stored potential energy in electromagnetic interactions.  This batch will be slightly watered down from that batch, and will focus on a variety of interactions (electric, magnetic, and gravitational). 

Possible Question Starters: 

"Two metal spheres, each carrying an electric charge, are moving closer together  in a closed system.  How does moving the spheres closer together affect the system?" 

correct answer -  the potential energy in the system will increase 

incorrect answer - the spheres will change direction 

"Which of the graphs correctly shows the relationship between an object's height and its gravitational potential energy?"