Half a croissant, on a plate, with a sign in front of it saying '50c'
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Synthetic Mexican Jumping Beans

We have the technology....
  [vote for,

Traditional mexican jumping beans are fun, but not that frisky and do eventually die.

These would have a metal shell with snap-acting 'dimples' that pop out at a certain pressure. Inside, a tiny charge of butane or propane. When held in a hand or placed on a warm surface, the gas pressure increases and the dimples pop out. Upon cooling, the pressure decreases and the dimples snap back to normal position.

afinehowdoyoudo, Mar 12 2014

Jumping discs http://www.grand-il.../Jumping_Discs.html
Have ordered - will probably forget to report. [MaxwellBuchanan, Mar 13 2014]

Copper(I) acetylide http://en.wikipedia...ki/Copper_acetylide
Makes things jump. [8th of 7, Mar 13 2014]


       This is so very clever. I want this to exist very badly.
Custardguts, Mar 12 2014

       According to the Pressure-Temperature-Volume Gas Law, it doesn't matter much what gas you use. Simply make sure the pressure inside the sealed "bean" is such that if the temperature goes up, the pressure increases enough to start snapping the dimples.   

       You should also have the dimples be made such that they snap at different pressures. That way the "bean" can jump multiple times as the temperature goes up and the pressure keeps rising.   

       Finally, you want to mark the bean such that you know which dimple will snap first, so you can set that side down. It snaps, and, by careful advance calculation/design, the bean jumps enough for Dimple #2 to be in position (face-down). It snaps, and the bean jumps enough for Dimple #3 to be in position....
Vernon, Mar 13 2014

       [+] And while you are at it, you might as well make them into intriguing shapes like cockroaches and tree frogs!
xandram, Mar 13 2014

       [21], you have to view such things in context. Remember that this is a product from the pre-video game world.   

       We didn't have enough pixels to go around when we were growing up. If you could find something that had a resolution level of on/off, you were holding state of the art tech.
normzone, Mar 13 2014

       I've seen "jumping discs" - bimetallic concave discs which "flip" when the temperature changes. I'll try to find a link.
MaxwellBuchanan, Mar 13 2014

       //According to the Pressure-Temperature-Volume Gas Law...// But, if you pick a gas with a boiling point somewhere in the right area...
MaxwellBuchanan, Mar 13 2014

       [MaxwellBuchanan], yes, I'm aware that the main text appears to be talking about liquid/gas phase transition at the relevant temperature. Such transitions are outside the way a gas alone behaves under the Gas Law. I was simply pointing out that it wouldn't be necessary to find an appropriate liquid -- note that butane and propane qualify as flammable and toxic. But compressed nitrogen should work just fine, and safely.
Vernon, Mar 13 2014

       I suggest super critical xenon gas. Its critical point is a few degrees below room temperature (or at rm temp in the UK I presume), and around 60 bars of pressure. I learned this when I left a xenon experiment alone overnight; the room temperature accidentally went way over normal rm temp and the container exploded. Need a pretty strong shell, but doable.
sqeaketh the wheel, Mar 13 2014

       Would't it be quicker and simpler to fill the "beans" with copper acetylide ?   


       Also, these beans appear to be quite small. It would be better if the acetylide-filled synthetic beans were slightly larger, perhaps the size of a coconut.
8th of 7, Mar 13 2014

       Well, while we're at it, we might as well throw some nitrogen triiodide into the mix!
afinehowdoyoudo, Mar 14 2014

       The choice of a phase-change (liquid-gas) material instead of a gas or an artificial muscle was meant to maximize the power density when absorbing heat not far above ambient... Not sure if that is correct, though.   

       Also, a charge of liquid working fluid would buffer against tiny leaks. A 'bean' filled with just air at ambient pressure would also work well in this respect, but would need a lot of heat to make it go. I like the idea of coconut-sized units: very manly.   

       I will await reportage of the jumping bimetallic discs with bated, if not held, breath.
afinehowdoyoudo, Mar 14 2014

       I envision these things as dimpled like a steel drum. And they would ring like a steel drum, especially if they caught some decent air on jumping.
bungston, Mar 16 2014

       Love it.
A sphericon-ish shape with a little twist could control orientation after each pop from the weight displacement.

       I can now report on the jumping discs (link).   

       They are discs, and they jump.   

       To elaborate, they are bimetal discs about an inch across, slightly concave (or convex, depending on your perspective). When warmed in the hand and pressed, they click to become convex (or concave, etc). When placed on a flat surface and left to cool for a few moments, they snap back the other way and launch themselves in to the air.
MaxwellBuchanan, Mar 16 2014

       The long winter evenings must simply fly by …
8th of 7, Mar 16 2014

       Self-uncorrecting-recorrecting Gömböcs
4whom, Mar 16 2014

       How large can such a disc be and still jump?
bungston, Mar 16 2014

       //How large can such a disc be and still jump?//   

       That's a good question. I would imagine it could be quite large. At large diameters, the thickness (of each of the two layers comprising the bimetal) would have to be greater.   

       At very large diameters, air resistance (actually the inability of air to rush in under the disc as it tries to jump) will stop the disc from jumping.
MaxwellBuchanan, Mar 16 2014

       It could be perforated to let air thru.
bungston, Mar 16 2014

       It could, but it would be simpler to do this on the moon. Less gravity, too. And a wide temperature range.
MaxwellBuchanan, Mar 16 2014


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