29 March 2016

This is not a perpetual motion machine


It just looks like one.

14 comments:

  1. I don't doubt that it's not a perpetual motion machine, but your "it just looks like one" is not particularly helpful. Why not give the explanation, since you know it?

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    Replies
    1. I don't know the explanation. But unlike some of our presidential candidates I do believe in the second law of thermodynamics, so I know it's not.

      There are readers here who will be able to debunk the video. Comments at YouTube suggest the room is being tilted.

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    2. The whole stage is rocking back and forth.

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    3. This may have something to do with it...

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    4. Nice find, Drabkikker! Perhaps small pins come up through the holes to tip the platform?

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    5. No idea. It wasn't me who spotted it, but Youtube commenter Joseph Lee.

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  2. what is the longest that a perpetual motion machine has run before finally succumbing to the laws of physics?

    I-)

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  3. I expect that the two balls will fall out of sync with each other and move in opposition. The machine will then stop and the conservation of energy is thus upheld. Any separated sets of processes with oscillatory motions will fall in and out of sync with each other for a short period of time. This can be seen in synchronous lightning bugs. The next time you're at a stoplight, with your turn signal on, watch the turn signal of the car in front of you. It will, for a brief moment, sync up with yours and then fall back out of sync, periodically.

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  4. The rocker is clearly driving the balls and not the other way round. If the balls were driving, you would see the movement slow down and accelerate smoothly at either end of the oscillation.

    A direct analogy to this complex-looking machine would be a coat hanger swinging on a clothes line. As one end falls down, releasing kinetic energy, the other end rises up, storing potential energy. We all know coat hangers aren't perpetual motion machines and neither is this.

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  5. My favourite one is this Boyle Flask. A million kudos points if you can work out how he does it without watching any other videos (hint: there's no need for any hidden parts in this apparatus). https://www.youtube.com/watch?v=287qd4uI7-E

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    Replies
    1. What immediately strikes my eye is that during the filling, the liquid level in the Tygon tubing doesn't match the level in the flask (which it should), and then clear liquid begins to exit the tubing before the green fluid rises to the top. I'll have to ponder this...

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    2. There appears to be a choke between the flask and the tubing, which I expect is important but a bit of a red herring for determining the real trick. Here are some hints, vaguest first:




      1) The energy for this system is chemical, rather than physical, but everything is visible and there's no secret adding of reagents. The liquid is commonly available and no chemical knowledge is necessary to prepare it.

      2) The trick is a little clearer in this HD version (full screen advised): https://www.youtube.com/watch?v=fQQ8_PDAdfI&feature=iv&src_vid=287qd4uI7-E&annotation_id=annotation_222713

      3) The trick is almost, but not quite, made plain in this video. A bit of basic chemistry and physics will yield the answer: https://www.youtube.com/watch?v=OS1KXMsE2qk

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    3. The introduction of air via foam makes me wonder if the principle of the trick is related to Heron's fountain -

      https://en.wikipedia.org/wiki/Heron's_fountain

      - but I still don't quite understand it.

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  6. It seems like the see-saw structure has some give to it. If the tipping action of the balls compressed the frame at all, there might be enough spring effect to at least extend the number of oscillations.

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