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Momentum is a mass's electrical resistance to change

  1. Jul 6, 2003 #1
    omg this is crazy guys...

    momentum is a mass's electrical resistance to change which all takes place on the atomic level, right?

    so for instance, a traveling cannonball doesnt want to stop because its field of electricity(created by it's atoms) resists contact with another electrical field...

    well, if the above is right, which im not sure is, then wouldnt a more geometrically enhanced body have more/less momentum??
  2. jcsd
  3. Jul 6, 2003 #2
    momentum = mass * velocity. In a more general sense momentum is mass in motion. Its unit is kg*m/s. Basically this gives an output of how hard something is to stop. Because a truck weighs more, it's harder to stop a truck at 30 km/h then a 6 kg bolling ball at 30 km/h.

    Edit: Well I'll add this then Mattius_. Momentum is not electrical interactions. Why would it be? If I set a ball moving in deep space, it keeps moving in the absence of electrical fields.
    Last edited by a moderator: Jul 7, 2003
  4. Jul 6, 2003 #3
    well duh, but i am asking what creates momentum. why dont things just stop on their own? what force keeps it going? what specific types of resistance characterize momentum?
  5. Jul 7, 2003 #4
    All bodies tend to keep thier movement. When moving body stops, some force, e.g., friction, exerts on the body. If there is no force, stopping body tends to stay stopping and moving body tends to keep going.Momentum is defined as neutroncount says. The tendency to keep going is not the result of force exerted on the body but the result of there being no force on the body.
  6. Jul 7, 2003 #5
    I think he is looking for a sub atomic explanation (if there is one) about how/why momentum is.
  7. Jul 7, 2003 #6


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    Mattius_ Where in the world did you get the idea that momentum is "electrical resistance"?
  8. Jul 7, 2003 #7
    I agree that momentum can be explained by Newtons first Law.

    But I think he might have been referring to the fact that if you were to push a crate for example, the electrons in your hand would repel the electrons surrounding the crate, and thus ultimately a Normal force put in place by an electromagnetic force is responsible for transferring momentum to the crate??? - Otherwise I dunno what he meant
    Last edited by a moderator: Jul 7, 2003
  9. Jul 7, 2003 #8
    yes the like charges in the electrical field are responsible for momentum... so momentum is only evident during acceleration...

    now when i said that geometrically enhanced bodies would have less momentum, what i meant was that a body that minimuzed the contact in the electrical fields (something with lots of surface area?) it would thus have less momentum because the interference in the electrical field on impact was minimized...
  10. Jul 7, 2003 #9
    WAY beyond my level of physics!
  11. Jul 7, 2003 #10


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    No mometum is simply the mass*velocity of an object. A body can have mometum when it is not acted on by any forces.
  12. Jul 7, 2003 #11
    ... that doesnt do anything for me.
  13. Jul 7, 2003 #12


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    Well that's all mometum is, it's the same for an object of any size (quantum and relativistic considerations excepted), it's not like the reaction force which is basically electrons repelling each other.

    mometum = mass* velocity (unless you put in the relativistic correction or find the momentum of a photon) that is what it is, that is how it is defined, simple as that.
  14. Jul 7, 2003 #13

    Okay, okay....
    I see your problem and its not that hard to understand.
    I just don't think anyone here has understood your question, thats all. First some corrections on what you said though...

    1) Momentum is not ONLY evident during acceleration. It is evident, during motion.
    (regardless of whether the object accelerates or not)
    The like charges between hand and crate are firstly responsible for creating a force on the crate. That force then has the POTENTIAL to accelerate the crate and if it does accelerate the crate and causes it to move, momentum will be transfered to the crate from the hand.

    2) There are like charges on the hand and the crate and there is an electric field between them, but it does not make sense to say
    "the like charges in the electrical field"

    ?? Do you understand now that momentum is evident during motion, not just acceleration?


    Keep in mind that the electrical force that a hand will exert on a crate is proportional to 2 things!!! The one is the size of the hand.
    (A greater area of electrons will naturally result in a greater repulsion) The other is the closeness of the electrons in the hand to those in the crate.
    (Are you beginning to get the picture of how this fits together?)

    If the person pushing the crate had a smaller hand (thus minimising electrical contact between hand and crate), and they were to exert the same force as someone with a larger hand... The crate would experience the same force, only because the samller hand is allowed to move slightly closer to the crate.

    Can you see now that the Force a crate experiences is not dependent at all on the size of the hand?? (the geometry of the problem)
    Therefore the acceleration, velocity and thus momentum are NOT dependent on the geometry of the problem.

    - I hope that helped
    Last edited by a moderator: Jul 7, 2003
  15. Jul 8, 2003 #14
    Go Gooogle, Type-Unrugh..this is What stops momentum.

    The first thing about your original post is I notice that you are trying to explain Unrugh Radiation, this occurs in a Extro-Galactic enviroment, and the Space between Galaxies, far..far away are Electro-Magnetic Fields, two-dimensional.

    And you are correct, the Geometric considerations are, if a body goes from Galaxy to Galaxy, he will be immersed within a Bath of Unrugh Radiation, this dispperses away matter contained within this sphere/shroud, the effect is a Transformation of Scale, perceptionally this when applied to inside Galaxies are the Equations that Lorentz And Einstein Grappled with, Geometric rods that contract and expand according to SR.

    A body that radiates itself away travelling between Galaxies, not only falls away(Falling body is really the action of Matter loss due to re-scaling) in Magnitude sense, it eventually radiates to such a degree, its Geometric Structure reduces to finite lengths, and thus has lost its original forward momentum.

    Space between Galaxies is not the same as s Spacetime inside Galaxies, the dimensional difference is of utmost importance.
  16. Jul 8, 2003 #15
  17. Jul 8, 2003 #16

    I have a crazy idea about momentum, but instead of explaining it with electric fields and what notI'mgoing to show you the connection between momentum and inertia. Yets say a l kg object was traveling with a velocity of 5 m/s north and we try to bring it to a stop. So lets say we apply a force great enough to bring it velocity down by one m/s every second. Every time we apply the force it will experience an interial force, and how many times that is would be found by 1kg*5m/s=5 kg*m/s. And I believe this is where momentum comes in persistence to motion. So I think momentum is really the combined inertia a body would experience in steps of slowing down to zero. Momentum is known of persistence to motion, and hence p in the momentum equation(p=mv). If anyone would like to add anything or doesn't agree please say so.[?]
  18. Jul 8, 2003 #17
    The "modern" view of momentum.

    The classical quantity momentum is proportional to the spacelike rate of change of phase of a quantum mechanical amplitude. The classical quantity energy is proportional to the timelike rate of change of the phase. The factor of proportionality is Planck's Constant h. We represent a moving object as a superpostion of waves, a wave train or wavegroup. The probability that we will find the object represented by the wavegroup, e.g. an electron, is the absolute square of its amplitude, so the object classically moves at the group velocity. The group velocity is:


    where p=momentum, E=rest energy, k=wavenumber and ω=frequency and C the speed of light,

    so that inertia is m=E/C2 classically or

    i= ω/C2 quantum mechanically

    As long as we don't change the rest energy or total momentum (wavenumber or total frequency) of a wavegroup it will continue to propagate in a straight, unaccelerated line. The property of inertia arises from the combination of quantum mechanics and special relativity, no deep mystery there.

    And that's the modern view.
    Last edited: Jul 8, 2003
  19. Jul 9, 2003 #18


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    Re: Momentum!!!

    No. The propensity of an object to keep going is not measured by it's charge but by it's mass. I can have to objects with the same charge but with different masses and the one which slows down the least is the one with the greater mass and hence the greater momentum. And please note that even light has momentum.

    What is a "geometrically enhanced body" ???

  20. Jul 9, 2003 #19


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    Nobody really knows the answer to that. It might be gravitational in nature. It has to do with Mach's Princple. See


  21. Jul 11, 2003 #20
    Re: Re: Momentum!!!

    But doesn't it take more force to accelerate or deccelerate a charged body? The electromagnetic energy of the radiation has to come from somewhere. So wouldn't that mean that a charged body has higher inertia and momentum?
  22. Jul 11, 2003 #21
    Electromagnetic wave has momentum on its own. If a charged body radiates electromagnetic wave, some momentum is carried away.
  23. Jul 11, 2003 #22


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    Re: Re: Re: Momentum!!!

    If the body is charged then yes. It takes a greater force to accelerate it. The difference in inertia is extremely small. But if there is no charge then the body still has momentum. How much charge does a baseball have?

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