Author: krecine1

Cups used for demo. Two sets of cups taped in different ways.
krecine1

Stable Rollers (Train Wheel Stability)

Two sets of cups are shown taped together. One set of cups is taped with the bottoms touching, so the part you drink from is on the outside for each cup. The other set of cups is taped with the tops touching, so the bottoms are on the outside.
  • Cups taped together in two different orientation can be used to discuss stability and why train wheels are shaped the way they are.
  • Although the set with the bottoms taped together is stable on a surface when stationary, it isn’t stable when rolling down an optical rail. The reason has to do with the effective size of the circle in contact with the rail on each side of the taped cups.
  • The set with tops taped together is stable when rolling and has a similar shape to train wheels, showing how train wheels are constructed for stability.
  • Original idea and deeper explanation available through this video
  • Cups located in L02, section B-4. Use an optical rail from L35.
Image shows metal tins for this demo in their location.
krecine1

Infrared Activity of CO2

Image shows tin containers for this demo in their location.
  • Demonstrate the greenhouse effect, as outlined here: https://aapt.scitation.org/doi/10.1119/1.5095383
  • Set everything up as shown in the link above; use a white trifold background. Be careful of reflections off of the plastic wrap in the direction of the camera.
  • Empty at least half of a CO2 canister into one of the tins and close quickly with plastic wrap and rubber bands.
  • Heat for approximately 4 minutes; may want to wait before doing this to allow the CO2 canister to come to room temperature (will be cold after filling).
  • Remove heat lamps and watch the results through the IR camera – should see that the CO2 canister cools at a slower rate.
  • Located in L01, section B-6
  • Full setup material list:
    • 2 lab jacks
    • 2 tin canisters (peanut containers)
    • 4 rubber bands (two per container)
    • Plastic wrap
    • IR camera on tripod
    • Extension cords
    • White trifold
    • 2 ring stands
    • 2 light bulbs (suggest 125 W)
    • CO2 canister for bike tire inflation

krecine1

Hand Crank Van de Graaff Generator

  • Located in L01, section A2
  • Van de Graaff generator that works by hand crank, so students can see the mechanism that charges the dome.
  • Turning the crank moves the belt, which has charges stripped as it moves and thus develops a net charge. Charges spread out on the dome as a result of its proximity to the charged belt.
  • Use the wand to demonstrate arcing and to ground the dome.