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Science questions not worth a thread I: I'm a moron!

Discussion in 'Science & Technology' started by The Imp, May 4, 2010.

  1. uppi

    uppi Deity

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    I would expect that an accurate physical model of lightning is actually a very hard problem. It's impossible to simulate directly, so you need to find an easier model. But I don't think things like magnetohydrodynamics are going to work, because it is a highly dynamical process.

    A phenomenological model like a random walk might produce a plausible result, but it wouldn't be very accurate. I don't know in what way it is supposed to be accurate, though.
     
  2. PlutonianEmpire

    PlutonianEmpire Socially Awkward Goofball

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    Photorealistic? I'm thinking like what you see in pictures or home videos. Or what you see with the naked ey when looking at a real storm?
     
  3. Berzerker

    Berzerker Deity

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    What impact on the Earth scarred the Moon ~4bya?

    You're assuming only prograde asteroids were flying around in the LHB, thats not what hit the Earth to cause the Moon's maria.

    Do you mean a Hohmann Transfer Orbit? That deals with spacecraft maneuvering. Can you explain how that works with planetary collisions?

    I'm not talking about prograde asteroids, but Moon+ sized retrograde object(s).

    The Earth cant be destroyed by an impact, only absorbed? Can it shed enough mass to lose angular momentum?


    I'm thinking ~30 degrees

    How did an asteroid hitting the Earth ~4 bya send asteroid sized chunks of crust and mantle into the Moon?

    "Shocks" precludes a large object entering our system 4 bya? I dont know that the debris came from a supernova, or was in orbit around a star that blew up, or just a loose planet.


    do you have a link for a precise integer precession?
     
  4. Bluemofia

    Bluemofia F=ma

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    Why can't a prograde motion asteroid do this?

    Just checking, you do know that the Earth and the moon rotate, right? So you can't just say there are impacts on one particular side of the moon that happens to be facing toward the direction of motion, right?

    Citation needed.

    Like, to a journal article, not a popular science magazine. That is an incredible claim that only someone who doesn't understand physics will make, or has very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very good reasons that will revolutionize physics as we know it.

    The Hohmann transfer orbit is firing the engines twice to change orbit from a lower to a higher, or a higher to a lower orbit. Once to produce the thrust to get into an elliptical orbit tangent to both the target orbit and current orbit, and once more to circularize the orbit.

    Large collisions would appear closer and closer to this because of the large momentum transfers at each collisions, and thus you will have a Mars-crossing Earth orbit if your situation is to happen, which will no doubt de-stabilize Mars' orbit within a few decades (not billion years, not million, not thousand, and not hundred. 10s of years). The only possible way is gradual accretion, which is already ruled out because of lack of retrograde material.

    Which do not exist because of their highly unstable orbits (retrograde motion is more and more unstable during denser and denser locations) de-orbiting them during planetary accretion. You will have almost none left during Late Heavy Bombardment.

    No. The velocity differences of asteroid-Earth collisions simply is not great enough to allow the Earth to lose mass in collisions.

    Then you need twice the mass to deliver the required retrograde momentum. So implying that the Earth formed at 20% of its current mass and then absorbed retrograde mass and sank into its current orbit. The greater the inclination, the more mass you need, as it provides less and less retrograde momentum.

    You are as far away from "formed in the asteroid belt" as you can get. That 40% is a minimum mass, not maximum mass.

    Physical size vs mass is different. An asteroid hitting earth would cause the Earth to gain much more mass overall than it releases, so there is a net gain in mass. Earth will not lose mass that easily.


    So, if this is the case, let's revisit your pet theory. Would not this imply a significant chemical dissimilarity between the rest of the solar system and the Earth? Clearly, extra-solar material being thrown onto the Earth would mean a completely alien composition.

    Why argue that the Earth formed in the Asteroid belt anymore? Why not just argue that it formed outside the solar system, and was captured by the sun? That's far more likely than an object pin-point targeting proto-Earth of less than 20% the current mass of Earth, from outside the solar system and striking in just the right way to cancel out enough angular momentum to sink it into a 1AU to 3 AU elliptical orbit, which is quickly struck by a large impact coming from the opposite direction from the Z axis (defined as the rotation axis of the sun perpendicular to the ecliptic) to cancel out the Z axis velocity and to circularize the orbit before it can destabilize Mars' orbit, or be disrupted by Jupiter?


    Yes. You. You are stating that this is the case earlier.

    I am saying that this is absurd as to claim that there is a special connection without physically justifying it.

    Let me try it again. This July 1st was a Monday. So does this mean that this is proof that the very first July 1st in human history is also a Monday? This is using your logic on orbital precession and rotational precession, but being very generous as you only need to fit 2 unrelated cycles, not 4.

    It is up to you to prove why there would be an integer number of precessions, in addition to proving a mechanic as to how Saturn could have "spat out" Pluto, and as to what caused Pluto's orbit to re-circularize (sorta), and to reconcile that with the fact that it has young rings and much much more problems that I haven't mentioned yet.



    Please, go hire a physics tutor if you want help with your high school (or middle school? It's been a while, and I don't know the curriculum at your place) physics class. You don't need to go through this convoluted way at trying to convince people you don't understand basic physics with these claims. You'll learn a lot more of physics and in greater detail and much more relevant to your studies than convolutedly asking about momentum questions to get a lesson on momentum. Try someone who is taking a calculus based high school physics class, or even a classmate who isn't failing. They usually aren't too expensive at the high school level, and can clear up a lot of the confusion you may have.
     
  5. Cheezy the Wiz

    Cheezy the Wiz Socialist In A Hurry

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    Hi guys. I need an electrical engineer, I'm having problems understanding rotating magnetic fields and induction motors.

    First, let me preface by saying that I don't understand calculus, so explanations involving it will be of no use to me.

    Alright. So, you have the stator at the center, creating a magnetic field, which rotates. What causes the rotation in the field? What creates the field? Is current run through a wire inside the stator?

    If I understand correctly, the rotating magnetic field interacts with the rotors around the stator, which induces current in them, which creates another magnetic field. When the stator and rotor spin at different speeds, then the magnetic fields interact in such a way that induces motion in the rotor. Is this so?

    Next question. I don't understand how slip works. Why is a difference in speed between the rotor and stator's current possible, when it reaches maximum speed? Or is this only intended to be applied with a load already on the motor, such that it has to "work" to try and get there?

    Is slip simply a measure of torque or potential torque?

    If I understand correctly, pushing the rotor to go faster than the stator's magnetic field creates negative slip, which reverses the flow of power back into the machine, which can then be used to generate electricity. This is done primarily by a turbine of some sort, as in a hydroelectric plant?

    Thanks for the help!
     
  6. Souron

    Souron The Dark Lord

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    ]Yes a stator contains electro magnets, which are powered up and down in such a way that the net effect is a rotating field. The rotating field create a current in the rotor, which creates a magnetic field, which tries to line up with the stator field. When the difference is small, the induced current is small, when the difference is big, the induced current is big. When the difference is zero, there is no induced current, so the rotor slows down to just bellow the stator's field's rotation speed.

    When a load is applied, the rotor is slowed below the rotation speed of the stator's field, so induction kicks, generating torque in the direction of the motor. This is balanced by the torque of the load, so the motors speed is constant for a constant load, but it's less than the speed of the stator field. Slip is the difference in these two speeds.

    Whether the stator is inside the rotor, or outside is not fundamental to the type of motor. Either is possible.
     
  7. PlutonianEmpire

    PlutonianEmpire Socially Awkward Goofball

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    I should know this, but I don't. :hammer2:

    How do I calculate the maximum stable orbit for a planet around a single star in a wide binary, such as Alpha Centauri, around either component?
     
  8. Mise

    Mise isle of lucy

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    Will frozen mercury burn skin? If so, what sort of "burns" would you expect? What kind of damage to your skin will it do?
     
  9. dutchfire

    dutchfire Deity Retired Moderator

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    I would expect yes, and that it will give similar results as similar very cold things. What would be special about mercury?
     
  10. Mise

    Mise isle of lucy

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    I don't know! Not a trick question, just saw an episode of Jonathan Creek that featured frozen mercury in it.
     
  11. Gigaz

    Gigaz civoholic

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    An ordinary metal at -40°C will probably not give you burns immediately, but you'd have a good chance to get stuck if you touch it with the bare skin and then you will get burns anyway. This should not happen with mercury because it would melt on contact. It will probably be as pleasant as touching a spoon that was heated by boiling water. The temperature gradient is the same. You won't get real burns, but you will feel pain.
     
  12. Arakhor

    Arakhor Dremora Courtier Super Moderator

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    Mercury is also poisonous by touch, so you'd probably get something else unpleasantly wrong with you as well.
     
  13. Gigaz

    Gigaz civoholic

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    Solid and liquid mercury is poorly absorbed by ingestion and skin contact. It is hazardous due to its potential to release mercury vapor.
     
  14. Arakhor

    Arakhor Dremora Courtier Super Moderator

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    Well, there you go. It's still unpleasant.
     
  15. Birdjaguar

    Birdjaguar Hanafubuki Super Moderator Supporter

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    The silence in this forum makes me think the threads should be merged into OT with RD tags.
     
  16. El_Machinae

    El_Machinae Colour vision since 2018 Retired Moderator

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    Yeah, or maybe an OP can ask a thread be moved from OT to here once it's had its run?
     
  17. Birdjaguar

    Birdjaguar Hanafubuki Super Moderator Supporter

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    I don't have a problem with that. this could be an archive once the heat dissipates.
     
  18. Harv

    Harv Emperor

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    The pace here is such that I can keep up with the discussion..... usually. :)
     
  19. Mise

    Mise isle of lucy

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    Probably the best of both worlds. I would prefer being able to see science/tech threads in OT rather than in here, but I would prefer to continue reading/discussing at a slower pace than OT will allow, once the initial flurry of interest dies down.
     
  20. El_Machinae

    El_Machinae Colour vision since 2018 Retired Moderator

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    I've certainly started threads in OT, just to get more interest. You'll see that these threads get a lot of views, but not many comments.
     

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