This is a true story. It happened to me. I was working on a high-school physics project with my two partners - the last project of the year, worth a significant portion of our grade. We had to build a Rube Goldberg-type device that would involve as many different kinds of energy transfers as possible. For example, a mechanical to chemical energy transfer would count as one, and an electrical to heat transfer would count as another. The goal was to get a ping-pong ball to fall into a cup at the end, as close to 1 minute after the start of the machine as possible. The entire device had to fit within a 50cm x 50cm x 100cm box. The group who got the best grade on the project would bring their contraption to the Science Olympiad state meet - it was the Mission: Possible event in Science Olympiad.

Here's what the machine did (at the time), as best as I can remember..

  1. cell phone dials a beeper
  2. beeper vibrates off a ledge
  3. beeper falling pulls a string, which tips over a small cup with acetone in it
  4. acetone spills onto a brick of styrofoam, dissolving it
  5. marble resting on styrofoam block falls down a ramp onto a mousetrap
  6. mousetrap slams shut, closing a circuit
  7. circuit powers a walkie-talkie with its code key button taped down
  8. walkie-talkies transmit across the box
  9. walkie-talkie beeps, making dancing flower dance
  10. dancing flower pulls string attached to mousetrap
  11. mouestrap slams shut, completing circuit
  12. circuit heats nichrome wire, from a toaster
  13. match, wrapped in nichrome wire, flares up
  14. incense, over match, begins burning
  15. string, over incense, burns through, releasing weights
  16. weights fall, pull another string which tilts a lever
  17. marble rolls down lever, down some ramps
  18. marble rolls onto 1/2 paper towel tube, resting on microswitch
  19. microswitch engages fan, blowing out incense and match (ball rolls off tube and turns off fan)
  20. incense smokes, setting off smoke detector
  21. smoke detector is rewired to engage a toy car remote-control
  22. remote-control car's wheels turn forward (never backward, since I glued a CD shard to use the knobby tires as a ratchet)
  23. car wheel acts as pulley, winding up string
  24. string tips up a balloon full of vinegar, attached to bottle w/ baking soda
  25. vinegar/baking soda mix, inflating balloon
  26. balloon inflates to tip lever, which closes a circuit
  27. circuit lights another match (same as before, with toaster wire)
  28. match lights a candle
  29. candle flame heats shrinky-dink
  30. shrinky-dink shrinks, connecting 2 paper clips clipped to it
  31. circuit closes, powering remote doorbell button
  32. doorbell button transmits to doorbell
  33. rewired doorbell powers low-amperage motor
  34. motor turns and connects circuit
  35. circuit engages lightbulb
  36. lightbulb powers solar cell
  37. solar cell turns low-amperage motor, connecting another circuit
  38. circuit ignites a model-rocket igniter
  39. igniter pops a balloon full of salt (in a funnel)
  40. salt falls down through funnel, into a cup of water
  41. water becomes electrolytic, completing a circuit
  42. circuit turns motor, knocking ping-pong ball in cup.

We had tested each series of transfers by themselves, but never the whole machine. During our first integrated test, late after school in the physics lab, everything began as planned. The acetone dissolved the styrofoam, the dancing flower tripped the mousetrap, which lit the match.

Styrofoam dissolved in acetone makes... napalm. And acetone itself releases highly flammable vapors. I had forgotten about these seemingly insignificant details. I'm sure you can guess what happened when the first match lit and there was acetone spilled everywhere.

Fortunately we had the foresight to place a tin underneath the acetone spill to catch most of the spilled liquid. A significant amount sloshed elsewhere. Most of the napalm also dripped into the tin, but some missed.

So our project fairly exploded. FOOM. We had burning napalm dripping everywhere. I immediately began trying to blow the fire out (with quick, high-velocity puffs), and so did one of my group members. The third member of the group calmly began having a seizure.

Luckily it was not well-mixed napalm. I eventually succeeded in extinguishing most of the conflagration outside of the tin. Inside the tin the better-mixed napalm just had to burn itself out. This variety of napalm happened to burn with almost no smoke, which was good, because it didn't set off the smoke detectors. We salvaged everything from our project, even the wires that were burning.

We changed the acetone/styrofoam reaction to water dissolving cotton candy. Much safer. During our class time run, everything worked almost perfectly. We got a 110 on our project, and just about everybody else failed. At the SciO State Meet, we got a visit from Mr. Murphy and everything completely failed to work. But at least it didn't explode.

On our way out of the building, we saw a janitor and asked if he minded us being here so late. He said "Nope, as long as you don't burn down the building."

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