delirium happy

Just keep on trying till you run out of cake

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Buckets of water
delirium happy
rho
I remember how when I was young, I heard it said that if you took a bucket full of water and swung it over your head fast enough, then the water would stay in the bucket and you wouldn't get wet. I was always sceptical of this at the time, and this was certainly never assuaged by the pathetic non-explanation that is "centrifugal forces".

Quite apart from the fact that centrifugal forces don't actually exist, and are a made-up engineer's fantasy to make some calculations easier, invoking them as an explanation is useless, because it doesn't explain anything. Saying "when you swing the bucket in a circle the water is pushed outwards because of centrifugal forces" is tautologous; centrifugal force means being pushed away from the centre when moving in a circle. As an explanation it's up there with "energy makes it go" in the uselessness stakes. Or to take a none sciencey example, it's like saying that Shakespeare was a great playwright because he wrote lots of Shakespearean plays. And yet explanations like this do persist in existing, and being very annoying.

What's even worse is that the actual real sensible explanation that lets people understand what's going on is really quite simple. When you apply a force to a moving object, it doesn't instantly stop its current motion and start moving in the direction of the force; it veers off it's origina path slightly. So imagine for instance, rolling a small ball along a table and then blowing on it at right angles to its motion. Or imagine throowing a ball through the air: gravity doesn't make it drop straight down, only veer off from its original direction to one that's going down as well as across. The bucket of water thing is like that. At the top of the circle, the water is heading horizontally, and gravity is pulling it downwards. Which means that it heads in a diagonal down-and-across direction -- whch is exactly how it should be heading to go around in a circle and stay in a bucket.

I'm quite sure I don't know what's so difficult about this explanation that the useless "centrifugal forces" non-explanation gets used instead. But anyway, ranty diversion over, and back to what I was actually meaning to say.

Back then, I was certainly never foolish enough to actually try this litte experiment, and I wound up forgetting a about it.

Then just earlier, as I was walking home from the supermarket, I suddeny remembered it and felt a strange compulsion to actually try it. I'm far more foolish now than I was back then, not to mention having sufficient autonomy to have easy access to a bucket, and much fewer qualms about making an idiot of myself. (Un)fortuantely, though, I haven't taken leave of my senses sufficiently to attempt doing this indoors (I contemplated the bath, but don't think that that would give me sufficient room to get a proper swing going), and seeing as I live in a flat I don't have any personal outside-space I can use.

The purpose of this entry is two-fold. Firstly, I want to know if anyone has actually attempted this, or seen it attempted, and if so whether the attempt met with success. Secondly, I want to have a written record of this thought so that I can stumble across it in n months/years time when I do have access to a suitable place to try it, and either think "ooh, what a good idea", or "gosh, I really was an idiot then".

(And I really need an icon for science geek type entries.)

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I've done it! It's so cool! We did it in the park outside school.

It's just a bitch getting the bugger to STOP. I think in the end I just let it go in the air and ran.

I've tried it, and yes, it really does work. Don't worry, you're not going to get water dumped all over you.

Getting water dumped all over me doesn't bother me in the slightest. Flooding my flat, on the other hand, does. As does having random passers by look at me as if I'm insane. Must try to work through that second one.

I think trying it outside would be a better option than inside... Whee, winter madness.

Oh, don't worry about the silly passers by. They don't know anything anyway. You can be teh misunderstood genius, doing silly physics experiments at your apartment, and they'll think you're crazy but someday you'll win the Nobel Prize and THAT'LL SHOW THEM.

:)

And when you are a Nobel-winning researcher, you can hire me to help out in the lab.

It certainly works with a bucket 3/4 full of water :).

I haven't tried it.

Next time I get a bucket, I will videotape myself trying it out, just for you.

I've done it to demonstrate things to people. I've had people claim I must have put gelatin in the water so it set, I answered that by pouring the water over my head (it was summer).

Current thing I'm trying to demonstrate is magnesium burning under water. I've seen this done, but I can't get it to work. When I plunge the burning Mg into the water it goes out rapidly. I think the water is quickly cooling the Mg and extinguishing it.

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Yep, this is what I thought. a big enough bundle of Mg ribbon should work though. I've just bought a 25m reel so I should have enough to get it to work...

How's that meant to work? You set it on fire in air, then that reaction generates enough heat to serve as activation energy for the magnesium/water reaction, and from then on that gives heat enough for it to be self-sustaining? It's been a long while since I've done any chemistry.

Yep, that is basically it. I don't have actual reaction energies to hand, but the burning Mg cracks the water to H and O2. The reaction between Mg and O2 then provides energy for the reaction to continue.

It works.

Just pick the swing up quick - I used a wide arc. But you can see it working even when you're a kid, clumsily bringing water up and in from the well - as kids we would (my godfather's kids and I) swing our buckets for fun, and when it was hot, dump water on ourselves. AFTER we brought in the water - no need to drip on Susan's floor!

Ah, fun times.

Done it, it works quite well if the bucket isn't too full, up until the point where you get a bit carried away and the centrifugal force[1] overwhelms the crappy bit of plastic holding the handle onto the bucket. The bucket goes flying off at a tangent wreaking watery flying-hard-object havoc wherever it hits[2].

[1] :]

[2] in my case, the shed window and a moderately drenched little brother.

Heh! Can totally imagine....

It does indeed work. The only problem is that you have to have it spinning fast enough the first time it goes over, so it's best to start with it going arround and work up as you spin it faster.

Yeah done it so many times it's really boring.

Good demo for C forces tho.

I watched a guy called Sooty Nick do it. Was surprised it worked, because the last time he did a trick was fire breathing, where his beard caught fire, and he got his Sooty nickname.

It's actually how we used to, in boy scouts, filter our coffee. It was cooked with the grounds right in it, and when complete, one would take the coffeepot and spin it -- because the grounds were heavier, they would spin to the bottom, and the coffee could be poured until it got to the bottom.

Stopping is, as everyone else has said, the problem. You need to slow over a half turn from horizontal to the ground, so that the water, when it stops, will fall into the bucket rather than all over the place. Typically, a bit falls out, but not enough to worry about.

Wanna steal this icon? just credit whomever it is listed.

i think the problem is that scientist types like to jargon up everything they say, so they can get away with saying less. centrifugal force, as you say, is an explanation of nothing, but if you know what it means it is a fine description of what is going on. when people spend too much time describing things, they forget the difference.

I only saw it on television - a Johnny Ball program.
Swinging the bucket in wider and wider arcs gets the water moving before turning it in a circle. Water in a bucket is surprisingly heavy. I'd like to try it with a bucket and water and you outside the bucket. A park in the summer?

It does work, though better to use a small bucket with only a little water. I didn't, and the handle came off in mid flight - ooops! *splooosh!*

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