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Dispelling Perpetual Motion and Unlimited Energy Misunderstandings

Discussion in 'Electric Vehicles' started by wk057, Apr 27, 2014.

  1. wk057

    wk057 Senior Tinkerer

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    #1 wk057, Apr 27, 2014
    Last edited: Apr 27, 2014
    I'm not sure if a similar thread exists... nor a more appropriate forum... couldn't find one, so, figured I'd make one. I'll assume that everyone reading this already understands that perpetual motion and violations of the second law of thermodynamics are impossible... if not: http://en.wikipedia.org/wiki/Perpetual_motion

    Ever since I purchased my Chevy Volt a few years ago, and now continuing with the Model S, every now and again I get someone who just has to argue against the laws of physics/thermodynamics. One of my favorite quotes...

    -Sir Arthur Stanley Eddington, The Nature of the Physical World (1915), chapter 4

    Yet, every now and then, someone will argue with me until they are to the point of actually being angry with me for disagreeing with them about various "ideas" on how to make an EV drive forever!


    • "Just put generators on the wheels."
    • "Just add a wheel to the back that generates power as you go."
    • "Put a windmill on top/in front grill/etc."
    • "Put a solar panel on the roof." (At least it shouldn't be a net loss like the rest...)

    There are people who honestly believe that things mentioned above, and other such nonsense, can actually make the car run forever, and will argue indefinitely defending their position!

    The first time I got into this discussion with someone, I knew the person pretty well and he was reasonably intelligent (I thought!). But when presented with reasons against these "ideas" he got extremely angered and irrational. He actually at one point said that "the government must have paid you off too so that these things can't happen."

    Left with pretty much nothing to say at that point, I ended the conversation with, "You're an idiot."

    This wasn't the only such occurrence. Over the past 3 years I've had this conversation/argument with at least a dozen individuals, and being generous, I'd say maybe half accepted reality in the end.

    I consider myself to be reasonably intelligent. While I lack grammar and spelling skills at times, I have a wealth of knowledge spanning electronics, programming, math, physics, and many other fields. To me, knowing that perpetual motion is impossible is just that simple: it's impossible. I have no further reason to question it. Why is explaining this to others equally impossible at times, though?

    Has any one else run into similar situations? What have your experiences been? Any particularly crazy ideas people have had?

    I'd really like to know where my arguments are failing when trying to help people understand these things. I don't fault anyone for having the misconceptions... for some reason thermodynamics aren't taught in grade school. But after explaining why such ideas can not work, I would think a reasonable person could accept this.

    Anyway, just throwing all of this out there...
     
  2. dhrivnak

    dhrivnak Active Member

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    Yes several times. If they persist I toss it back saying I am not smart enough to make it work so challenge them to make a working prototype. If they do they would become quite rich I tell them.
     
  3. pgiralt

    pgiralt Active Member

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    You're not alone. First day I owned the car I went to Auto Zone to pick up some cleaning supplies and the guy behind the counter was trying to tell me about his amazing idea of putting a generator on the car to recharge the battery. After trying unsuccessfully to explain to him why that wouldn't work, I gave up. I've heard the windmill idea a couple of times as well.
     
  4. HankLloydRight

    HankLloydRight Fluxing

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    Oh yeah, before I bought my MS, I started reading the TM forums (before I found TMC).. and I found a thread from someone asking "how many alternators would it take to power the MS?" (or something like that). They had convinced themselves that with enough alternators and belts attached to the wheels, you could self-power the car. And they were really serious. Like dozens of alternators strapped onto the body. I don't know where that thread is, but I when I started reading the forums, I though due to the advanced technology of the company, the cars, and the "price of admission," that that might just raise the level of discourse to slightly above average for the internet.

    Nope.
     
  5. stopcrazypp

    stopcrazypp Well-Known Member

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    This is actually possible, but requires there to be actual wind (the car works in principle like a sailboat).
    http://www.popsci.com/cars/article/2012-07/wind-powered-car-travels-upwind-twice-speed-wind

    This is also possible, but requires sacrifices to the car interior:
    http://grist.org/news/solar-powered-sedan-hits-dutch-streets/

    The other two don't work "perpetually" (only applies in terms of regenerative braking).
     
  6. pgiralt

    pgiralt Active Member

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    This is the one you're thinking of:

    alternators
     
  7. rabar10

    rabar10 FFE until Model 3

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    <--- See the avatar for what that has to look like if you'd like to be able to drive 150 miles or so per day. College team project with cross-country races every two years.

    Not much room for groceries in there. Ended up roughly the shape of a cockroach, so might not win too many style awards either. But given enough time and sunshine, it could (and did) transport someone 1600 miles without plugging in.

    And yes, we had to answer all the same questions about just putting a generator on one of its wheels...
     
  8. HankLloydRight

    HankLloydRight Fluxing

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    Right.. I could have sworn that wasn't on TMC but on the TM forums. Thanks.
     
  9. wk057

    wk057 Senior Tinkerer

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    #9 wk057, Apr 27, 2014
    Last edited: Apr 27, 2014
    Well, I don't totally dismiss the solar panel idea, but I do explain that it would be impractical to be the sole power for the Model S.

    I figure if we were able to get 100W of solar panels on the MS, covering the roof, hood, etc... then lets see... ~5 hours of full sun per day average (commonly accepted, accounts for rainy days?)... so, 500 Wh/day... * 365 days/yr = 182kWh/year = ~600 miles per year, before conversion efficiency losses. So if you park the MS in the sun every day, and drive about 12000 miles per year, covering the car in solar could potentially cover 5% of the electricity.

    There are some pretty obvious hurdles to this...

    • Maintaining aerodynamics
    • Conversion to usable charge voltage efficiently
    • Added weight of components needed
    • Negative effects of leaving the car in the sun constantly
    • Cost vs ROI (180 kWh is something like $30...)

    I'm sure there are more...

    I had completely forgotten about the wind powered car, actually... I'll have to use that as an example next time. :p
    Still not something useful for the MS....
     
  10. dsm363

    dsm363 Roadster + Sig Model S

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    Yeah. That was one of reasons I stopped checking official Tesla forums. One person in particular wouldn't stop talking about perpetual motion in multiple threads even after multiple people presented him with the facts.
     
  11. Doug_G

    Doug_G Lead Moderator

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    You're probably right. One of the reasons I stopped reading the TM forums was the low signal-to-noise ratio - especially the constant perpetual motion postings littered all over the place.

    - - - Updated - - -

    ...what he said.
     
  12. bonnie

    bonnie Oil is for sissies.

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    I don't know why you all make it so complicated with generators and wind turbines and solar panels. I just plug my Roadster into my cigarette lighter and recharge while I drive.

    (I know, not original ... but it's my favorite response to these people.)
     
  13. MacroP

    MacroP Member

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    #13 MacroP, Apr 27, 2014
    Last edited by a moderator: Apr 28, 2014
    Look at post # 3
    alternators

    Looks like the TMC forum has drop a few dB today unfortunately.
     
  14. wk057

    wk057 Senior Tinkerer

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    Wow, I actually have not heard that one. :D
     
  15. PaulusdB

    PaulusdB Mayor Gnomus Vintage Limb

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    LOL. You might need one of these to make that work...
    559727_LB_00_FB.EPS_1000.jpg
    Belkin AC Anywhere Omvormer 300 W in de Conrad online shop
     
  16. physicsfita

    physicsfita Member

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    I'm convinced that most of the perpetual-motion people on forums are trolls or delusional. They've usually had the science explained to them enough that they *should* know better.

    For people in real life, I have had some luck using the First Law instead of the Second. (I got a lot of this when the Prius was relatively new in Michigan -- I miss the "Prius time" -- enjoy the "Tesla time" while it lasts!) I point out that the alternators (or whatever) get hot, which most people agree to, and then use that to show that you can't get all the energy back.
     
  17. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    I try not to let myself get sucked into 'discussions' concerning politics, religion or perpetual motion, and for the same reason: recent studies have shown that the reasoning centers of the brain simply shut down when people are confronted with ideas that go against their deeply held beliefs.

    As for the solar panel idea, I simply point out that a good rooftop solar panel puts out about 200W and that it takes about 20,000W to move the Model S down the road at highway speeds. The visual of 100 solar panels on the roof of a car usually gets the point across.
     
  18. Zextraterrestrial

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    but if you made a big sail out of 100 panels you could use the wind and sun too! (just watch out for power lines and bridges etc...)
     
  19. Reykjavik

    Reykjavik Member

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    It is possible that the second law of thermodynamics doesn't actually hold under all circumstances. It may be that near the speed of light some quantum thing happens and the law is true only on average, or just breaks down entirely. But to believe that is the case we are going to need a working demonstration of it.

    Also, a windmill on the car would be able to provide propulsion if the wind was blowing across the car sideways. The same physics that enable sailing also work on land.
     
  20. Zextraterrestrial

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    ...but going into a headwind would require zig zag roads :frown:
     

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