Episode 20: Exploding Jawbreaker, Static Cannon, Deadly Playing Cards
- A jawbreak can explode after heated in a microwave: confirmed
- Static discharge off of a PVC pipe can kill: mythbusted
- An ordinary playing card can kill you with a powerful throw: mythbusted
This is not a mythbusting as it actually happened, but don't know exactly why. A jawbreaker exploded in a kid's hand after he heated it in a microwave. Same thing happened to another kid, severly burning her face.
The theory was that it was due to temperature differential, which was supported with some microwave testing on a jawbreaker cut in half. They were able to see that one of the inner layers was more heat sensitive and melted before the others, becoming very hot in the process.
Tried multiple combinations of cooling and heating and eventually got a jawbreaker to explode when they crushed it with the mechanical jaw (a steel-toothed contraption built by Tory). They weren't taking proper precautions so Christine got hit in the face and burned and Adam got hit in the arm (both were fine).
The microwave heating was the leading theory, given that it matches the actual events and was reproducible, but they wanted to test other theories. The first was the chemical reaction theory -- caustic soda or lye somehow contaminating the candy during the manufacture process. They mixed separate samples of caustic soda + jawbreaker ingredients and lye + jawbreaker ingredients.
- Added water to caustic soda and lye samples, but nothing really happened.
- Dry caustic soda + jawbreaker mix exploded in the microwave. The lye + jawbreaker mix got hot but did not explode before the lye did.
- Dry caustic soda + jawbreaker mix being warmed in a toaster oven was enough to make it explode as well.
The final theory was checking to see if the plastic bag containing the jawbreaker had any effect. They left a jawbreaker + packaging in toaster oven to simulate leaving under the sun for several hours and then put it into the mechanical jaw, but it wouldn't explode. When the dissected it, the jawbreaker was molten on the inside.
Myth: construction worker one the job and finds and 8" PVC pipe that's beat up a little. He wants to reuse it, so he starts cleaning it with a sandblaster. The pipe builds up charge, becoming a static cannon that unloads its charge on him and kills him.
voltmeter to measure charge on pipe and ammeter on Adam's copper hand contraption to measure amperage of static discharge.
No static charge on pipe whatsoever in initial testing.
They decided to make a Van de Graff generator out of PVC pipe as well as a lyden jar to see if either of those would produce interesting results. They built up several hundred thousand volts or charge with the Van de Graff generator (no element of sandblasting involved), but as evidence by their playing around with it and sparking each other, it wasn't enough to do real damage.
The lyden jar + PVC pipe combination did even less. The subjected it to the sandblasting, but the most they got was a 20mA discharge.
One potential explanation was that the sand blasting may have helped dissipated the charge via dust in the air. Regardless, static discharge doesn't seem like much of a killer.
Playing cards as weapons (Killer Deck)
Myth: an ordinary playing card can kill you with a powerful throw.
Adam is really good at throwing cards (been doing it since he was 10), so this was a personal mission for him.
Ricky Jay: card throwing expert, author of Cards as Weapons, a book describing the use of the playing card as a weapon. He can throw cards up to 90mph (Adam can only throw 25mph).
Adam wants to build a machine that can throw a card. He and Jamie face off in their competing designs, and as always, Jamie's simple design (modelled on a baseball pitching machine) wins out. Adam tried to replicate arm mechanics with a spring loaded mechanism and fake fingertips, that he admits was "over elegant." In Jamie's words, "Adam actually had a pretty clever idea. It doesn't work, but it was pretty clever."
Jamie's design was pretty awesome. It flung cards through two spinning wheels at 70mph. I want one. One of the spinning wheels did break apart due to the 30,000 rpm speed. I still want one.
The rebuilt throwing machine (with metal wheel) flung cards at 150mph. I'm not sure if I want the card throwing machine or the penny gun more (the penny gun seems more portable).
They tested on ballistics gel to measure how it might actually penetrate human flesh.
Ballistics gel experiment: * 1/4" with Adam throwing. * 1/2" with 150mph card throwing machine * 7" with pellet gun * 20" with heavy crossbow bolt
After it was pretty clear that even the super gun wouldn't do much damage, Jamie offered to be the target for once. It drew a little bit of blood, but not much more.