Project 1 — Pen-refill launcher

Last updated at September 16, 2026 by

  • Remove both the ends from a pen so that the refill can slide freely through the barrel. Fix the pen cap to the side of the barrel and attach a rubber band to the clip of the cap. Connect the free end of the rubber band to the refill using a safety pin. Stretch and release the rubber band. The refill shoots out.
  • GIF Watch: pen-refill launcher — more stretch, more distance Animation for the pen-refill launcher project. A short looping GIF, three or four beats, drawn in the flat classroom style of the chapter. Beat 1 — A full person assembles the launcher: pen barrel, cap fixed to the side, rubber band from the clip to the refill with a safety pin. Beat 2 — The person stretches the rubber band a little, releases, and the refill shoots a short distance, labelled elastic potential energy to kinetic energy. Beat 3 — The person stretches it much more and the refill flies much farther, with distance markers comparing the two — more stretch, more distance. Label every arrow and quantity, keep every label inside the frame, and hold the last frame for a moment before the loop starts again.
  • What it shows — the conversion of elastic potential energy into kinetic energy .
  • Repeat with different amounts of stretch and observe how the distance travelled changes.
  • Is there a relationship between the stretch and the distance travelled?
    • Yes — more stretch, more distance .
    • More stretch = more work stored in the band = more potential energy = more kinetic energy given to the refill = it flies farther.
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