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Impulse Engine (Drive) ...a stupid question?

  1. May 16, 2015 #1
    Recently, I've been watching a lot of those youtube videos debunking gyroscopic propulsion because everything about it violates the second law of motion or something........

    This got me thinking, if I was floating in space and I decided to swing a large rock on a rope around me, to generate some centripetal force on the rock, then let go of the rope (it's a really long rope and I'm attached to the slack), I'm assuming it would just float away from me given the centripetal force. Now, since I'm attached to the rope, and given newton's second law, I would be able to pull my self a significant distance given the mass and velocity of the rock. Correct?

    Assuming this is correct, would something similar to this effect be possible on the quantum level with electrons and magnetic fields or something?
  2. jcsd
  3. May 16, 2015 #2


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    You move some distance, to rock moves in the opposite direction. At some point the rope does not allow more motion, you and the rock are stopped (in the frame of your original position) and you end up with exactly the same speed as before. Yes you moved a bit, but the rock did that as well, if you pull it back you end up in the same position as you started.

    You can move around everything with energy, but I don't see the point. You cannot change your velocity, and you cannot even permanently change your position (in your rest frame) by a relevant amount.
  4. May 16, 2015 #3

    Dang it, you're right. My first thought was that the amount of energy expended in generating a large centripetal force should transfer to distance gained when I pull on the rope after I let it go, but instead, after you let it go, you traveled in the opposite direction at a proportional speed. Thanks.
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