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One Picture, Four Hour Debate

  1. Mar 21, 2015 #1
    I would love to hear your feedback on this picture guys. I'm not an engineer, but I drew this several years ago as part of an invention idea (hydraulic fluid used to spin a turbine, energy conversion). I've gone WAY past this in my invention, but, my partner and I revisited my sketch book for an addition pertaining to this drawing. We could have built it in less time than we debated it. He insists the picture is drawn wrong and it wouldn't work. It hurts my brain. Thoughts?

    Hydrolic.jpg
     
  2. jcsd
  3. Mar 21, 2015 #2

    DaveC426913

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    Adjusted for clarity.
    Hydrolic.jpg
     
  4. Mar 21, 2015 #3

    DaveC426913

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    I have no idea what 4 fulcrums and 4 planks of wood have to do with spinning a turbine. I know it doesn't matter to this sub-problem, but you haven't defined what this sub-problem is. What's it supposed to do? You ask if it "works". What works?

    Will the left and right corners go up? Depends. The connections between the planks, are they rigid, or will they flex?
     
    Last edited: Mar 21, 2015
  5. Mar 21, 2015 #4
    The picture is a machine. Applying pressure to corner moves the machine; or at least that's the theory. As a side note, which is irrelevant to the drawing, we are working with compressed fluid flow (fluid dynamics) to transfer hydraulic pressure into electricity.
     
  6. Mar 21, 2015 #5

    DaveC426913

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    Moves it where? Across the lawn?
     
  7. Mar 21, 2015 #6

    OmCheeto

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    Most engineers and scientists I've run across, don't draw half as well as you do.
    And your physics is correct!
    [tex]Area = \frac{Force}{Pressure}[/tex]
     
  8. Mar 21, 2015 #7
    Bottom left corner.... if you walked up to that and stepped on it what would happen? Assuming ofcoarse that the boards were hinged or connected in some way, shape or form.

    LOL thank you Cheeto.
     
  9. Mar 21, 2015 #8

    DaveC426913

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    You'd tear the nails out of the boards at the connection points. Or are the connection points flexible? Are they even connection points? Maybe the boards are just lying on each other.

    Let me assume they are simply lying on each other. That means the boards can move with respect to each other.

    I see now. Yes. Both weights would lift. But the near weight would not lift as high as the far weight.
     
    Last edited: Mar 21, 2015
  10. Mar 21, 2015 #9
    Lets assume the boards are connected a door hinge, rope or cable. Yes, something flexible to allow the machine to move.
     
  11. Mar 21, 2015 #10

    DaveC426913

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    It would work. Your friend is mistaken (assuming I have the starting move correct: i.e. stepping on point sw).

    Stepping on point sw would pivot W.
    That would raise nw and the weight on it.
    Raising nw would pivot N, dropping ne.
    ne would push down on E, causing it to pivot.
    E pivoting would raise se, and the weight on it.
    Stepping on S would also raise se, and the weight on it.

    Hydrolic.jpg
     
  12. Mar 21, 2015 #11
    That's what I said! But he insists that the machine would only rise one foot, not the two feet as drawn. The machine would be even on all four sides.

    If the four boards were replaced by four fluid tanks (or for this scenario four 5 gallon buckets connected with pipe on the bottom), according to him, it would take 3x more energy to lift the corner back up as well. We argued it for 4 hours lol. I might just build the damn thing to alleviate any doubt.
     
  13. Mar 21, 2015 #12

    DaveC426913

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    He's not here to defend his stance, so I'm not about to say categorically he's wrong - there could be many unspoken assumptions. But, as-drawn the weights would rise 2 feet.

    I can't speak to this either. I can't see it being a direct analogy between seesaws and tanks of water. You'd need to do another diagram.
     
  14. Mar 22, 2015 #13

    russ_watters

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    I think the reason why you are having so much trouble agreeing with him is the same as why the posters in this thread are having so much trouble helping you: you are providing shockingly little information on which to base any conclusions about what happens. You have great art skills, but you are not engineering your "invention".

    An additional piece of information needed: how tall are the fulcrums?
     
  15. Mar 22, 2015 #14

    DaveC426913

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    Heh. Good point. One of those unspoken assumptions I was talking about.

    I think it is a safe one though: before the device is even activated, we know the fulcrum must be at least one foot high. Which means after activation, the low points will rise at least two feet.

    If the assumption is in error, it errs in favour of the device lifting even higher than 2 feet.
     
  16. Mar 22, 2015 #15

    russ_watters

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    Sure, that's an easy one. So why would that cause an argument...?
     
  17. Apr 4, 2015 #16
    Thank you everyone for the replies. I apologize, I didn't think the drawing would go into such detailed discussion. It's a theoretical problem that I attempted to use art to answer. I thought if I could visualize it then I would have my answer. We have put this on the side for now. The short version is we are experimenting with hydraulic pumps to convert energy. The drawing represents an automotive suspension system (and several other potential applications). In the case of an automobile traveling down the road the wheels and suspension have a substantial amount of vertical travel (potholes, natural and man made terrain features). We're trying to exploit that and extend the range of electric vehicles by converting this potential energy into electricity. This is something that a major auto part manufacturer in Detroit played with back around 2005. They deemed it too expensive to keep researching. I think they made a mistake when they overlooked it's potential marketability. I'm busy this Easter weekend but afterwards I'll put together another drawing. Thanks again for your replies.
     
  18. Apr 6, 2015 #17

    russ_watters

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    That's an intriguing idea. I wonder how much energy is available and could be harnessed.

    But I know it can be done: I have a pair of skiis that have piezoelectric cells in them to absorb vibration, lighting a little LED on them.
     
  19. Apr 6, 2015 #18

    NascentOxygen

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    The temperature rise of vehicle shock absorbers might be an indication of the energy available.
     
  20. Apr 7, 2015 #19

    OmCheeto

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    I had never thought of that. This idea is similar to one I came up with several years ago. (I collect and devise ways of extracting wasted energy from vehicles.)
    In my design, instead of one shock absorber, two are used per wheel.
    When the vehicle travels over a pot hole, the spring pushes the wheel down, along with air pump #1, and ports the pressurized air to a central air cylinder, which is fed by all four wheels. The same thing happens when the vehicle exits the pot hole, with air pump #2.

    The amount of energy extractable is easily calculated from just knowing the mass and speed of the vehicle, and the geometry of the pothole.
    Well, ok, there are other variables that complicate things. But textbookish, back of brain thought experiments should start out simple.

    And like many of my ideas, other people either developed them first(BMW Turbosteamer), or published before I did.

    And they solved the engineering problem I had:

    Yay! It looks like it got past the "this might work" phase:

    Levant Power Corp. is MIT's spinoff company.
     
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