[QUOTE=UncleRojelio]
So that’s how they built Stonehenge.
[/QUOTE]
Yes. Now you just have to figure out how the prehistoric structure that built the monument produced liquid nitrogen and insanely strong fabric, without cheating and invoking celestial perambulator or bug-eyed aliens from Zeta Reticuli.
Stranger
[QUOTE=Stranger On A Train]
The work required to pull the rods back together (to “push the ball up”) is, if we neglect friction, the same required to lift the ball…
[/QUOTE]
Really? I thought the ball was actually dropping the whole time, but the contact point with the rods was rising (relative to the earth), giving the the* illusion* of climbing? I guess upon reflection I can see how the rods would act as wedges, though.
[QUOTE=Princhester]
What about an axe? Or some sort of mechanical axe. Gold is soft, like you say.
[/QUOTE]
Insufficient data. I’ve never played with gold in bulk. FedEx me a bar and I’ll let you know!
Seriously, I think you’d run into a scaling problem with a hand axe. Certainly you could chop thin gold rods with an axe, but as the target gets bigger, the impact pressure drops (increasing impact area), and the gold that you’re attempting to displace to either side of the blade has nowhere to go. I think the best you could do against the ball would be to leave some deep gashes.
A monster mechanical axe could work, of course. With enough force, you can push anything hard through anything softer, more-or-less! No idea how big or powerful such a device would have to be, but I think we’re getting into steam hammer territory.
For cutting little chunks off, I think the best bet would be a big angle-grinder. For full-on sectioning, wire spark-erosion would definitely work, or possibly abrasive water jet cutting. I’d be interested to see what could be done with a thermic lance, plasma cutter or linear shaped charges though! A gold ball is unlikely to be available, but big copper objects must exist and need cutting occasionally.
It would be nice if you could chill the ball with liquid nitrogen and then shatter it to bits, but gold doesn’t become brittle on cooling like steel does…
[QUOTE=goodie]
“OK kids, any of your junk not picked up off the floor in 10 minutes is going to get pulverized by my giant gold cleaning ball, Yes!, even the Legos! Mwuhahahahha!!!”
[/QUOTE]
I might in fact kill for a 1m ball of solid Lego, if it was made of assorted bricks and colors. Probably be worth more than Au, anyways…
[QUOTE=Rhythmdvl]
Would the gold deform and slosh through right away?
[/QUOTE]
Gold is only “soft” compared to steels and other alloys that we use as structural components. Pretty much any pure metal is soft - that’s what alloys are all about! But you’ll find it’s plenty hard when the ball runs over your foot, or if you trip and bang your face on it.
If your gold ball maintains at least 10cm[sup]2[/sup] contact area with the rods, it’ll be fine. A couple of square inches. Otherwise, the contact pressure will squidge little grooves onto the ball’s surface. But that’s all. Cover the rods with a half-inch of truck-tire rubber and it’ll stay all pretty… till it drops through and smacks a great big flat spot onto itself on the floor!
[QUOTE=Rhythmdvl]
Would hardened steel rods be strong enough to support it (assuming it didn’t deform first)? How long would the rods have to be to make it to the table?
[/QUOTE]
They both depend on how steep you want to make the incline! And what diameter you make your rods… my WAG is that it’d be difficult to scale up the game in your link to a 1m diameter gold ball, yet keep the same proportions. You might have to live with the rods being disproportionately thick. But with decent alloy steel, or maraging steel if you really want to get fancy, you could probably build something like it.
[QUOTE=astro]
Other than some super conducting magnetic levitation effect (and gold is only very weakly magnetic) I don’t think there is any medium that’s going to “float” a dense ball of gold.
[/QUOTE]
Well, there’s one element that has a melting point lower than that of gold, yet a higher density - Americium. In theory, one could simmer one’s gold ball in a soup of Americium at 1000[sup]o[/sup] C and it would float.
Of course, this would require more Americium than has ever existed on Earth, but I’m assuming money’s no object.
[QUOTE=Darth Nader]
I might in fact kill for a 1m ball of solid Lego, if it was made of assorted bricks and colors. Probably be worth more than Au, anyways…
[/QUOTE]
[QUOTE=Stranger On A Train]
The work required to pull the rods back together (to “push the ball up”) is, if we neglect friction, the same required to lift the ball. The amount of force you have to apply is actually greater because there is some component of force on one rod that is parallel to the ground that you are actually reacting on the other side. In other words, you are actually making more effective work for yourself. With a ball bearing, the reaction force isn’t significant, but for something this size it would be like trying to cut tungsten with fabric scissors. Never mind the required tensile and bending strength these rods would need to have to support this weight to begin with.
Here’s my suggestion for lifting it up. Make yourself a big toroidal bladder of some really super high tensile, non-elastic material. Slip it under the ball (if you can’t even roll the ball then you’ll need to make it in halves or with a split like a toilet seat, then seal the ends back together). Pump a slurry of liquid nitrogen into the bladder and wait for the heat stored in the ball to cause it to evaporate and expand. After it lifts up the now-chilled ball, pump water into the middle of the torus until you fill up the interior volume. (The water is just at standard pressure so it doesn’t have to be especially leak-proof.) As the water freezes, it will expand, lifting the ball off of the torus, which is no deflating as the gas within cools as well. Now build a platform for the torus up to the level of the supporting ice pillar and repeat until you get the appropriate height.
It’s not an especially thermodynamically efficient method owing to the ineffiencies in using liquid nitrogen but LN[sub]2[/sub] is pretty cheap and this method doesn’t require any heavy lifting, super long levers, a massive system of pulley blocks, et cetera. The major trick (besides this beyond exotic material fabric) is simply maintaining appropriate thermodynamic equilibrium so that the nitrogen gas doesn’t contract faster than the ice cools. This is just a matter simple axisymmetric conductive heat transfer since everything is in quasi-static equilibrium.
Stranger
[/QUOTE]
This seems awfully complicated.
If the sphere weighs 22,300 lbs, and the projection of the bottom surface area is 1194 square inches, then you only need a bladder to exert 18 psi to lift it.
[QUOTE=beowulff]
This seems awfully complicated.
If the sphere weighs 22,300 lbs, and the projection of the bottom surface area is 1194 square inches, then you only need a bladder to exert 18 psi to lift it.
[/QUOTE]
What fun is that?
Stranger
[QUOTE=Stranger On A Train]
What fun is that?
Stranger
[/QUOTE]
Who am I to poo-poo the use of liquid Nitrogen? 
[QUOTE=yastobaal]
Something like this?
[/QUOTE]
Thank you from the bottom of my heart for that link.
My 8 year old just watched Indiana Jones for the first time last week, I showed him that video, very neat. I’m afraid things like that give him the idea that being an adult is more fun than it really is, though.
So beautiful!
Should have sent … A poet!
[QUOTE=Bryan Ekers]
Well, there’s one element that has a melting point lower than that of gold, yet a higher density - Americium. In theory, one could simmer one’s gold ball in a soup of Americium at 1000[sup]o[/sup] C and it would float.
[/QUOTE]
What’s the density of liquid Americium?
[QUOTE=Stranger On A Train]
Here’s my suggestion for lifting it up. Make yourself a big toroidal bladder of some really super high tensile, non-elastic material.
[/QUOTE]
I think that “Big Toroidal Bladder” could become the next great SDMB username. Or rock band.
RR