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What would happen or would this work?

  1. Jul 29, 2004 #1
    A round tube evacuated of any gases (maybe constructed in space) surrounded by electromagnets. A ferrous material is constructed inside the tube. Say maybe a BB (as in BB gun) by use of electromagnets create a rail gun type of effect around the circle tube and then the velocity of the BB is steadily increased using the rail gun technique.


    With the absence of friction because of the vacuum (or as near to one as what construction in space will allow) and the BB being so manipulated as to keep it in the center of the tube. What speeds or velocities are possible using the rail gun type of model?

    When the top speed is increased if possible to attain any significant percentage of C (light) would manipulation of the BB up and down by way of the electromagnets, have any type of effect such as the experiment where you spin a bicycle tire and hold it by the axel while on ice, i.e. when you move the axis in proportion to the rotation you get movement of the whole system. Or in other words would you get a gyro type effect even though there is not a direct connection between the BB and the center of the circle?

    for instance if the BB is suddenly moved up would the entire model move up? and for how long?
  2. jcsd
  3. Jul 29, 2004 #2
    the maximum speed attainable is c, or the speed of light. Your second question is kinda confusing, could you explain a little more. (By the way, isn't this a linear accelerator)

  4. Jul 29, 2004 #3
    Not quite c. Objects with mass can never attain light speed.
  5. Jul 29, 2004 #4
    If the BB is traveling let us say at 10% of C and is traversing in the center of the tube, held there by the same magnetic field which is accelerating it around the tube. Then by manipulating the magnetic field (much like in an accelerator when they change the trajectory of particles to make them collide) the trajectory is changed from the center to say within 1/10 the distance from center to the edge.
    iow, as I said sort of like the experiment where you are standing on ice with a spinning bicycle tire held by the axels and you then tilt the axel. The net effect is that the person holding the apparatus (spinning bicycle tire held by the axels) will rotate or turn in the direction of tilt.
    With the BB traveling at a percentage of C would not it's mass increase? and when its' orbit is abruptly changed would not the entire mechanism (tube,BB, and electromagnetic apparatus) move in the direction of change?
    I would think such speeds are attainable, seeing as how particle accelerators attain such speeds now; but only with subatomic particles.
  6. Jul 29, 2004 #5
    Theoretically, there is no maximum (only a supremum) - you could always increase the speed a little further, but the linear velocity would never reach (let alone pass) the speed of light. In practice, the maximum speed is dictated by how much energy you can provide and how fast you can switch the electromagnets.

    As for your 2nd question, if I understand it correctly: I would guess that the system would move in the opposite direction, on account of Newton's third law, striving to keep the center of mass stationary.
  7. Jul 29, 2004 #6
    :eek: Well, there you go ! Can I itch a ride to Alpha Centaury whenever you rig that system up on a spaceship ?!
  8. Jul 29, 2004 #7
    Well, no. Center of mass remains stationary, remeber? Unless you have a huge amount of mass to throw out, or have plenty of time to waste, you're basically screwed. :wink:
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