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Weight gain of a fully charged Model S

Discussion in 'Model S: Battery & Charging' started by scottm, Mar 7, 2017.

  1. scottm

    scottm Version 9 software sufferer

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    No, the grin is not wider on a full charge. Because the car is heavier and will be slower...
    you know, toting extra 3 micrograms around.
     
  2. Joe F

    Joe F Disruption is hard.

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    OK, I'll brush one grain of salt off that last french fry. All right, maybe I won't eat the last fry…
     
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  3. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    #23 ShockOnT, Mar 15, 2017
    Last edited: Mar 15, 2017
    It has the energy that would weigh 2-3 micrograms if it was converted to mass, but it isn't, so it doesn't weigh anything.
    It arrived in the car as energy and leaves as energy, so no weight change.
    If you were able to convert the charge energy to mass your car would weigh more, but then you wouldn't have any energy to drive it.
    Basically you can have either, but not both, otherwise it would be E = E + mc^2.
    Sorry if this was answered further up-thread.
     
  4. Larry Hutchinson

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    Wrong. What part about the equals symbol do you not understand?
     
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  5. GSP

    GSP Member

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    The "pure energy" in a fully charged battery does add to the mass. However it may be not as same as the mass equivalent of the Wh stored. Or, maybe it is. I don't know.

    @Mario Kadastik helped by posting the correct calculation for the mass added by charging a few years ago. I tried to search for it, but it is hard to find things that far back in time.

    GSP
     
  6. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    You can convert mass to energy, but the energy doesn't have the same mass. If it did, you'd be able to convert that mass to energy, and so on indefinitely (which you can't).
    The equal symbol in E = E + mc^2 was used to highlight this incongruity.
    You'll have ponder that on your own, I'm off this thread.
     
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  7. scottm

    scottm Version 9 software sufferer

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    I think he meant E = mc^2 which is an equivalence.
    (Not the funky E = E + mc^2 you introduced, just a fancy way of writing m = 0 which is bizarre in this context).

    Look at E = mc^2
    Solving for mass, m = E / c^2
    That there is your mass of the energy, plain and simple.

    Energy has mass!!

    And .. the world is not flat.
     
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  8. Larry Hutchinson

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    Yup. And as for the world being flat, apparently there are some basketball players that think it is.
     
  9. Zetopan

    Zetopan Member

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    That particular form of self caused brain damage extends well past "some basketball players". Do a Google search on "flat earth celebrities" and you will get about 1 million hits listing lots of people. Idiot rapper BOB actually argued with Neil deGrasse Tyson about a flat Earth. It is important to always remember that the Flat Earth Theory "has members all around the globe".
     
  10. tga

    tga Supporting Member

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    And remember, those people can vote... :eek:
     
  11. David99

    David99 Active Member

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    E = mc^2 is what you use to calculate the added weight. Energy is what bends spacetime and creates gravity, whether that energy is free or contained within binding energy of "matter". Every physicist will tell you that by adding energy you are adding mass. In our world the amounts of energy we dealing with are so small that we can never detect any change of weight. Just as much as we never experience the effects of relativity because we live in a world of pretty weak gravity and we are moving not anywhere near the speed of light. Nevertheless relativity is real.
     
  12. scottm

    scottm Version 9 software sufferer

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    What to blow minds further? Just how slow current moves in a wire. People think electrons move lightspeed fast through wire, but it doesn't. Electrical movement, or current, flowing in a wire is creepy slow ... as compared to electricity moving outside a wire (e.g. lightning).

    The reason why it's slow is there's a helluvalot of electrons in the volume of copper it takes to make a wire.

    The actual velocity of electrons through a conductor is measured as an average speed called drift speed. This is because individual electrons do not continue through the conductor in straight line paths, but instead they move in a random zig-zag motion, changing directions as they collide with atoms in the conductor. Thus, the actual drift speed of these electrons through the conductor is very small in the direction of current.

    Drift speed through a copper wire is typically a quarter of a millimeter per second. That's so slow it'd be hard to observe movement with the naked eye, if only electricity were visible.

    So that's the "push speed" the battery is giving your motor in the Tesla. And man does that motor react !!
     
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  13. tga

    tga Supporting Member

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    Does drift speed vary with current? How does copper compare to other metals?
    How does it compare to (ionized) gas during lightning? Or a gas discharge tube light?
     
  14. scottm

    scottm Version 9 software sufferer

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  15. jdjeff88

    jdjeff88 Member

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    Of course the answer varies depending on the grade and source of electricity you are putting into the batteries. Power produced by Earth-friendly renewable power is lighter and airier than power produced from a coal plant, unless of course you are talking about Green Coal, in which case, again, you save a bit of weight. Now if you run your power through a filter (like those Monster Energy Centers) that smooth out your power, again you can appear to save weight (but that is mostly an illusion as the smoother wave just means the car jiggles less when charging). I've been trying to tap into some of that nuclear power electricity, as that is some of the finest in terms of quality, and nuclear sourced electricity isn't just light, it actually reduces the weight of the battery it is in (something about weak nuclear forces or somesuch)! Not as much as natural gas electricity of course (which floats), but premium grade, high btu content natural gas electricity can be expensive in some parts of the country.** Science is bigly good!

    **Source: A Primer on Rick Perry's Department of Energy (2017)
     
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  16. tga

    tga Supporting Member

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  17. Electroman

    Electroman Well-Known Member

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    I would tend to think ShockOnT is correct.

    When you heat a metal rod to 500K, you add energy to the rod, but it doesn't weigh even a bit more than before.
     
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  18. scottm

    scottm Version 9 software sufferer

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    I know, hey? That's what common sense would tell you.. but this stuff isn't common.

    A lot of things go on with metallurgy when you heat things, including ions flying off..

    But if you were to contain it... yes, the metal rod would weigh more when hot.

    Here's a look at heating water, which weighs more.

    E=mc^2 is universally true. I bow down to the person who finds the exception. The world bows down to the person who proves it.
     
  19. Electroman

    Electroman Well-Known Member

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    Very cool, Scott. Thanks for that link. That one explains things in so clearly that even I was able to understand. In effect, when you heat a body, even though you are not really adding additional atoms or molecules, but the additional energy imparted makes the object weigh more - so in a closed system containing 1 Kg of water an increase of 100K would increases the weight equivalent to adding 154 trillion molecules of additional weight, even though no additional atoms were injected into the system.

    So weight is not just an exact conversion of the number of atoms in a body, there is an additional element of how much energy it has. That energy could be heat (in which case the atoms are moving fast within the system) or it could be kinetic like the object moving at speeds comparable to speed of light.. This weight of an object approaches infinity as the it tends toward speed of light - which gives rise to the theory that no particle can go at the speed of light, without transforming itself into an electromagnetic wave.
     
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  20. tga

    tga Supporting Member

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    TMC really is one of the coolest forums on the 'net...
     

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