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Power Plant - Will it Work?

  1. Jul 27, 2010 #1
    Power Plant - Will it Work???

    I updated my idea today! Please let me know what you think, good or bad, I don't get offended. Thanks for your input! It might be a little clunky but please see attachment. Thanks everyone for your thoughts, good or bad, doesn't matter!
     

    Attached Files:

  2. jcsd
  3. Jul 27, 2010 #2
    Re: Power Plant - Will it Work???

    lol good thing you don't get offended because I'll tell you that it won't work.

    There is no "immense pressure", the pressure is still 5000lbs divided by the area of the piston (that u have labeled as 1000lbs). It cannot be repeated because you lose energy in the from the water just by touching it. Even with zero electricity produced it will die out after 1/2 of a cycle. There isn't enough energy left to bring up the other ball.
     
  4. Jul 28, 2010 #3

    russ_watters

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    Re: Power Plant - Will it Work???

    Jack, the main thing you're missing is that the "skateboards" have to be motorized and use more energy than the system produces (and probably need a winch to lift the 5000 lb weight to put it on the little piston).

    Also, it is kinda odd that you are showing the side of the piston with the 5000 lb weight small - it means the 1000 pound sides barely move.
     
  5. Jul 28, 2010 #4
    Re: Power Plant - Will it Work???

    sorry the label 1000kg is erroneous as it came from the image that i copied for my diagram. The motorized skatboards just move left to right, either providing slack to the rope or removing it. They don't do any work other than just sliding left to right. It is basically a smart pendulum:

    http://en.wikipedia.org/wiki/Pendulum
     
  6. Jul 29, 2010 #5

    russ_watters

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    Re: Power Plant - Will it Work???

    It's not just a smart pendulum: you can't harvest energy from a pendulum continuously. Changing the slack means you're applying a force to make it move. I think you'd actually have to fully develop the concept and do the math to prove it to yourself. The math isn't hard, it's just a potential energy accounting.
     
  7. Jul 29, 2010 #6
    Re: Power Plant - Will it Work???

    It doesn't require math, just logic.

    If you resort to math to prove such trivial, "common sense" concepts, you are doing it wrong.
     
  8. Jul 29, 2010 #7

    russ_watters

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    Re: Power Plant - Will it Work???

    While I agree, it's still a reality that some people need to see it.

    Virtually all perpetual motion machines have the same design "feature": they are just complicated enough that the designer doesn't/isn't capable of analyzing them properly. The OP probably understands that you can't harvest energy continuously from a pendulum, but has created a pendulum system complicated enough s/he can no longer analyze it.

    A pendulum is just ke-pe=0. But add a few components and you get ke-pe+ke-pe+ke-pe....=0 Miss a component and you end up with a non-zero energy per cycle!
     
  9. Jul 29, 2010 #8
    Re: Power Plant - Will it Work???

    True.

    When I was in my teens I would always design perpetual motion machines and then try to figure out why they don't work. Some of them were hard and required some pondering before you see the flaw.

    Its a good exercise and helps you think logically and be observant. If you aren't creative enough to make up your own examples, look some up on the internet and try to figure them out. Some of them are really good and requires some abstract thinking to figure out where the flaw is.

    This one is a super easy one though.
     
  10. Jul 29, 2010 #9

    DaveC426913

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    Re: Power Plant - Will it Work???

    jajknight, as an exercise in analysis, answer me this:

    Once the 5000lb weight has pushed its piston down, it is lower than when it started. You've extracted its potential energy (once).

    How do you then lift the 5000lb weight back up to start again? Where do you get the energy from?
     
  11. Jul 29, 2010 #10
    Re: Power Plant - Will it Work???

    If you want to take out any energy out of the PE of the ball it must drop down a certain distance(h1 to h2). To repeat the same step again the ball must be returned to its initial height. If you just move the top part of the rope to the left to get rid of the slack you will have a pendulum but that will only go up to h2 where you can't get any more energy.
     
  12. Jul 30, 2010 #11
    Re: Power Plant - Will it Work???

    "How do you then lift the 5000lb weight back up to start again? Where do you get the energy from?"

    Hi bp_psy/Dave - the skateboard moves enough distance to the right so that when the ball is released from the holding platform it has enough energy to swing to the required height. All the best.
     
  13. Jul 30, 2010 #12

    DaveC426913

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    Re: Power Plant - Will it Work???

    How does the skateboard lift the 5000 lb weight back up to its original height?

    You can isolate this part of the contraption from all the rest. If you were able to get this one part to work, you could extract energy from it directly, and eliminate the whole water-piston thing.
     
  14. Jul 30, 2010 #13
    Re: Power Plant - Will it Work???

    No it does not. The height that the pendulum reaches is determined only by the height from which you release the mass not by the angle the rope makes with the vertical axis. In order to get the mass back to the initial height, the skateboard would have to pull it hard enough to lift it.
     
  15. Jul 30, 2010 #14

    russ_watters

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    Re: Power Plant - Will it Work???

    You can certainly swing the weight up using the lateral movement of the truck: that's how you twirl an object on a string around your hand (like a yoyo). But as I said above, moving the truck to make it swing requires input energy. That's the energy missing from the OP's analysis.
     
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