h a l f b a k e r yFlaky rehab
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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.
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]
[link]
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This is so very clever. I want this to exist very badly. |
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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. |
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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. |
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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.... |
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[+] And while you are at it, you might as well make
them into intriguing shapes like cockroaches and
tree frogs! |
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[21], you have to view such things in context. Remember that this is a product from the pre-video game world. |
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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. |
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I've seen "jumping discs" - bimetallic concave discs
which "flip" when the temperature changes. I'll try
to find a link. |
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//According to the Pressure-Temperature-Volume
Gas Law...// But, if you pick a gas with a boiling
point somewhere in the right area... |
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[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. |
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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. |
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Would't it be quicker and simpler to fill the "beans" with copper
acetylide ? |
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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. |
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Well, while we're at it, we might as well throw some nitrogen triiodide into the mix! |
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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. |
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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. |
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I will await reportage of the jumping bimetallic discs with bated, if not held, breath. |
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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. |
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Love it.
A sphericon-ish shape with a little twist could control orientation after each pop from the weight displacement. |
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I can now report on the jumping discs (link). |
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They are discs, and they jump. |
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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. |
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The long winter evenings must simply fly by
… |
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Self-uncorrecting-recorrecting Gömböcs |
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How large can such a disc be and still jump? |
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//How large can such a disc be and still jump?// |
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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. |
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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. |
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It could be perforated to let air thru. |
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It could, but it would be simpler to do this on the
moon. Less gravity, too. And a wide temperature
range. |
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