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Centrifugal force in space Motor with axle and wheight

  1. Apr 1, 2015 #1

    I've read a lot of posts on centrifugal and centripetal force in space. But they mostly refer to the spinning space stations.

    I would like to know what happens when you take a motor with an axle and a mass on the end on of the axle, and you start the motor up.. I understand the whole law of "every action has a opposite equal reaction".
    But does this mean the motor will follow the mass in a small circle or will the whole thing just "hang" there wobbling about?

    Does anyone know if it has been tested in space?

    To add to my question...

    If a person in a "spinning" spaceship touches the side and gets "caught" in the "gravity".. Does it make the ship off balance?

    I hope you get my question - understand it I mean.. It's bugging me.
  2. jcsd
  3. Apr 1, 2015 #2


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    Staff: Mentor

    Welcome to PF!

    The Hubble Space Telescope uses exactly that concept to aim it. The motor spins the wheel one way and that makes the Hubble spin the other way:

    And yes, astronauts moving around in a spacecraft will affect its attitude. Fortunately, the astronauts are a lot lighter than the spacecraft so the effect is small.
  4. Apr 1, 2015 #3
    Thanks for the speedy reply and the link to the Reaction wheel.

    I assume the speed of the wheel and the mass of it will be determined by the mass of the ship.

    All of this is relevant to my experiment of the last 4 years.
    A theory similar to that of Nikola Tesla's Flying machine.
    But I would Like to see my Experiment Succeed or Fail..
    Before I make any claims.
  5. Apr 1, 2015 #4


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    Staff Emeritus
    Science Advisor
    Education Advisor

    I think you need to go back and understand something simpler.

    Two masses, m1 and m2, are connected via a rigid rod with negligible mass. So you then set it to spin in your "space", i.e. no friction, no gravity.

    They will both spin about the center of mass of the system! The location of the center of mass depends on the mass m1 and m2, and how far apart they are. If m1=m2, then the COM will be right in the middle of the two. For the Earth-Moon system, it is close to the center of the Earth since m_Earth>>m_Moon.

    You need to look at your "motor-axel-mass" with this level of understanding.

  6. Apr 1, 2015 #5


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    Staff: Mentor

    You're welcome!

    Also worth noting that despite your title this doesn't have anything to do with centrifugal force.
    Uh oh. That can't lead anywhere good. Note that:
    1. What we are discussing can only cause rotation, not translation.
    2. Internal action causing translation would violate conservation of momentum.
    3. We don't deal in things that violate the laws of physics here.
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