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Pain or Urban Myth?

Discussion in 'General Discussion' started by TexMex, 16 Oct 2005.

  1. TexMex

    TexMex

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    If you ever watch the grand prix where two well matched drivers are seperated by a small margin, you will notice that their difference (in distance) varies with their speed. As they slow down for the corners, they will be very close, but as they accelerate down the straight the distance streches out. This is no mystery, it is simply that their difference in TIME is remaining constant. 1 second at 30mph is a lot smaller than 1 second at 200mph.

    Now if we pour a constant stream of water out of a vessel, it too, is subject to acceleration. As a result each part of the stream is being pulled away from the surrounding stream. In due course, surface tention adds the final thrust, and breaks the water into pieces. So even a constant trickle of water will hit the ground as a series of drips.

    So what I'm wondering is, does it really hurt when you wizz on the electric fence, or is it urban myth. After all, there isn't a solid core of water between the body and the fence. Just a series of drips (albeit that they hit the fence in pretty rapid succession).

    I have in mind an experiment to safely evaluate this. If you were to stretch a piece of wire between two stakes (electric fence fashion). Connect this to one side of a multimeter. Next connect the other side of the multimeter to your body (possibly by means of a jubilee clip). Then have a wizz on the wire and measure the resistance. I suspect it would still be in the order of Megs.

    Any takers? This is one occaision where I'd like someone to take the proverbial. :LOL:
     
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  3. Richardp

    Richardp

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    Is this a trick question ?:cool:
     
  4. Mudster

    Mudster

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    Many years ago when I worked in London, I'd been for a night out and was catching a late train home, we were delayed and it took a dogs age to get home.

    Next day we found out some poor chap had had a skin full, was stood on the station and it was quiet, the toilets were a long walk down the platform, so he took a **** ontot he track's hit the live rail and it was curtains......damn unpleasant way to go.
     
  5. Softus

    Softus

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    Fascinating question TM, and very clearly described.

    However, I'm not sure I agree with your conclusion about the series of drips. I have a couple of photos from Alton Towers where they shoot those arcs of water with very clean solonoid-operated valves - the 'bits' of water on the fall of the arc are clearly all connected to each other.

    I agree with your reasoning based on acceleration, but I suspect that the column of water is made narrower by surface tension in order to compensate for the effect of acceleration.

    This is a very non-scientific way for me to look at the problem, but it's just a way of provoking further further discussion on an interesting topic. And I have the ideal candidate for your experiment - someone used to p****ng into a headwind. Are you listening oilman?
     
  6. Big_Spark

    Big_Spark

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    Let me dispel this myth...as thats what it is.

    Urinating on an electric fence will not induce an electric shock, and nor will ****ing on a live rail of a train track. People claim this will happen, but it is simply not true, they are urban myths.

    I have seen this performed and can assure you that no-one got fried as a result..and we are talkling the full 650 V DC third rail...
     
  7. Softus

    Softus

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    You have the advantage, having seen this being performed.

    Can you provide TexMex and me with the same experience? :evil:
     
  8. SparkyTris

    SparkyTris

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    Balls. It happens, all right. The fluid is being forced down, so although it will eventually break up into separate droplets, after 3 feet it can still be an unbroken stream of fluid. An agricultural electric fence works with roughly 1Hz pulses of near-DC electrical energy, with a potential of up to a kilovolt (I think)

    Chances are that by the time a pulse comes along, the fluid will be bridging the gap body-conductor and conductor-ground, so most of the current will go for the earthier path conductor-ground. But you can certainly feel some of it go conductor-body-ground.
     
  9. Softus

    Softus

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    Ah, but with nobody there to witness your reaction, can you be sure that what you're feeling is real? :confused:
     
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  11. petewood

    petewood

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    Why not?
     
  12. SparkyTris

    SparkyTris

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    Good point. Very Zen.
    Its's a great question. I think you could estimate the EWLI (Earth Whiz Loop Impedance) painlessly with an ordinary hi-z meter. I will try this when I am back on dry (or at least moist) land. But I'm sure that the EWLI would be lower at kV level. Now I don't fancy hooking myself up to a megger.
    Also, where to stick the probes or clip the clips?
     
  13. empip

    empip

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    Cannot remember the footwear, but during our youthful country life, en route home from the 'local', a group of us whizzed with unerring aim in the general direction of the single strand ... ouch! reasonably painful spasm in the calf muscles felt by more than a couple, of which I was one !!
    No effect on whizzer ... although, is 254mm normal? The stricken three of us are forever named 'the gang of ten' .. :D :D :eek:
     
  14. AdamW

    AdamW

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    Having performed some experiments on "finite time singularities in a fluid jet", I can tell you that a stream of liquid breaks into droplets due to the Rayleigh Criterion. It's all to do with fluids of varying densities intermixing.

    Basically, your jet of wee-wee can still be one continuous stream quite some distance from you.

    I found that even wrapping a jumper around your hand is not enough to protect you from an electric fence. OUCH
     
  15. Slogger

    Slogger

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    this was done as an experiment on the program MYTH BUSTERS and there conclusin was yes you do get a jolt albeit they used a model with sencors mounted on it and orange juice for the urine

    they have exposed a lot of myths on this program but then again they dont use live human beings they are loooking for volunteers and they err on the teers side

    MYTH BUSTERS needs you
     
  16. Richardp

    Richardp

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    Do you mean holding your willy with a jumper wrapped round your hands
    ? cos you could use tongs :LOL: :LOL:
     
  17. empip

    empip

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    'Jumper cable' to metal gatepost ? :D
     
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