Fall 2014

Mechanics, heat & thermodynamics
August 23, 2014 at USC

Sponsored by USC, SCAAPT, and the Brown Foundation
Also many thanks to our generous materials donors: Educational Innovations (teachersource.com), Arbor Scientific, Xump

Kinematics

  • Stumbling block: “speed = velocity = acceleration = position”
    • Try having students use complete sentences and descriptions.
    • Ex: “It’s going 50” “The velocity of the car is 50 meters per second.”
    • Ex: “It’s going up” “The velocity of the person is increasing“
    • "No 'It'" sign... The word "It" is banned in my classroom
  • Stumbling block: “Which equation do I use?”
    • Try having students learn motion and forces in discrete “models”. Most introductory physics classes can break down their motion and forces unit into “models” such as “constant velocity”, “constant acceleration”, “balanced forces”, “unbalanced forces”.
    • You can also try having students solve “goal-less problems” (http://kellyoshea.wordpress.com/2011/03/05/goal-less-problems/) – problems that don’t ask the students to solve for anything.
      • Ex: “A student stands on her skateboard at the top of a hill, then begins to roll down.” Students are then supposed to write everything they can about the situation (draw a force diagram, “her speed increases, assume no friction”, etc.)
    • The stuff above on PowerPoint
  • Speeding camera Tickets
  • Bill's demos and graphing using a running person (handout given at workshop)
  • James' story about jackalope, used as a context for graphing
    • Have students graph this on a position vs. time graph and/or velocity vs. time graph. All situations are constant velocity.
    • Highlights:
      • Driving at a constant velocity
      • See jackalope, continue traveling the same velocity
      • Jackalope starts running at a greater constant velocity. You follow.
      • Jackalope stops. Staredown.
      • Jackalope runs back to hole. You pursue in reverse, a slower, constant velocity compared to before.
      • Jackalope runs into the hole where you originally spotted it. You stop there.
      • ~Fin~
  • Inertia demonstrations
    • Swinging masses
    • Toilet paper pull

Newton's Laws

Circular Motion

  • Bill's presentation
    • Centripetal vs centrifugal force
  • Frank's circular motion demo
    • I show a clip from the movie "Wanted", in which the characters can cause their bullets to follow a curved horizontal path after fired. "Is this possible?" I segue to the question "Do objects in circular motion follow the Newton's Laws that we learned?" (The video was taken down from YouTube, so I'll try to upload it to Dropbox and post a link here.)
    • Let's try by swinging objects on strings! :oP I use styrofoam balls so nobody gets hurt.
    • Circular motion video clip
      If you open the file using Apple Quicktime, you can pause the video and advance or reverse frame-by-frame using the arrow keys on your keyboard.

Other Featured (and Wasn't-Featured) Stuff

  • physicsvideos.net
    James' collection of physics videos, many created by himself
  • Colliding metal spheres demo kit
    Converting kinetic energy to thermal energy - how can this be explained using the model of temperature increases being defined as faster-moving molecules?
  • Frank's physics video bookmarks
    Every time Frank bookmarks a physics video, it shows up here. You can filter by clicking on the list of tags at the top.

Helpful Links Suggested by Fellow Teachers

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