Lava Lamp Centrifuge
neil.fraser.name
neil.fraser.name
"The centrifuge is a genuinely terrifying device. The lights dim when it is switched on. A strong wind is produced as the centrifuge induces a cyclone in the room. The smell of boiling insulation emanates from the overloaded 25 amp cables. If not perfectly adjusted and lubricated, it will shred the teeth off solid brass gears in under a second. Runs were conducted from the relative safety of the next room while peeking through a crack in the door."
Read the rest to learn if a lava lamp will work on Jupiter or during a space shuttle launch (2.3 or 3 Gs).
Thats the (Tesla) spirit!
Back when I was in high school I did a bit of biology research one summer. My lab's ultracentrifuge had a lid which was solid 3/8 to 1/2 inch steel plate. Working the lever to slide it to the side was a good reminder to ask the question "Are you sure you've properly balanced these (nitrocellulose) test tubes?"
There are some problems in this video that have since been corrected, but check it out: http://www.youtube.com/watch?v=mK2vpqXk8Jc
It's not an entirely new concept (cf. http://www.staber.com/), but our approach to the door and very ingenious and novel.
The energy stored in this goes by the radius squared. But the centripetal force on the object at the end goes by the radius.
So a smaller faster one is less dangerous, and also requires a less powerful motor (or the motor you have can give you a higher force).
Although the bearings are probably a bit harder to handle when it's faster, the whole thing will weigh less.
On the con side, a smaller one will have a larger difference in force between the top and bottom of the lava lamp, making your experiment less accurate.
The velocity of the shrapnel tracks the energy stored in the device. Meaning a larger radius has faster shrapnel.
Note: velocity as used in my earlier message is circular velocity, (AKA RPM), not linear velocity.
For visualization: the ice-skater who spins slowly & pulls arms in. By spinning faster, no energy is lost, as can be seen by extending the arms. However, a slower-rotating device can more easily be predicted and avoided / hand-stopped if needed.
Which would you rather try to stop, with your bare hands, assuming identical energy? A 1-inch pipe spinning at 10,000 RPM, or a large tire spinning at 10?
Remember that with the larger slower RPM one, the radius is higher so the linear velocity is high too, even if the RPMs are slow.
Now picture it going several times faster in terms of RPM, and tell me when it'd be safe to stick your arm in its path.
Lets scale it up. Picture the earth. Near the equator, the linear velocity is almost 1000mph. Scale it down to the size of the centrifuge in the video, while keeping linear velocity the same. I can easily point out when half of the earth is facing the sun. Could you point out when the centrifuge is pointing north?
But I am more concerned with what happens if you do actually get hit. Or if it comes apart, or falls down.
And if you do get hit, or it breaks, a smaller faster one is MUCH (exponentially much) safer.
The force goes up by the RPM squared, but it goes down only linearly by radius. You don't need to speed it up very much to counteract the smaller size.
On the other hand the energy goes up by radius squared. Meaning the smaller size helps a LOT in terms of destructive power.
One question though: is energy->radius^2 based on angular or linear velocity?
So yes, when you increase the radius the linear velocity goes up even though the angular one doesn't change.
This is awesome. Everybody should do something this awesome in their lifetime.
edit: Yikes, anyone got a torrent / mirror for those videos? They're crawling at sub-30kbps for me.
http://dl.dropbox.com/u/363028/temporary/3g-side.3gp (16mb)
http://dl.dropbox.com/u/363028/temporary/3g-floor.avi (159mb)
http://dl.dropbox.com/u/363028/temporary/3g-payload.avi (43mb)
Please mirror / set up a torrent if you can, I'd prefer to not nail my Dropbox too hard. (payload is interesting, you can see the twisting caused by the spinning)
Have you ever opened up a lava lamp? The bottle is capped with an old-fashioned pull-off bottle cap. I guarantee that if anything goes pearshaped, it'll be the integrity of that cap.
So the circumference is 9.5 meters, times 42 per minute = 395.6 meters per minute = 14.76 mph or 23.75 km/h http://www.wolframalpha.com/input/?i=3+meters+*+Pi+*+42%2Fmi...
What the heck is that thing made of, anyway? An erector set? Juice bottles? Over-powered wires and motors? That beast is worthy of a Frankenstein moment.
I agree, who's spirit can only be really captured by a large toggle switch mounted on the wall that you have to flip which dims the lights as it happens.