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G Forces experienced by human if rotated inside a giant hampster wheel

  1. Mar 17, 2013 #1
    I am working on an a project that consists of a giant wheel with a 30m radius that will be rotating at a velocity fast enough to keep a human on the inside surface of the wheel without being attached.

    Please refer to 30s in for reference of similar motion performed by a hamster:

    Can somebody please help me in calculating the speed at which the wheel needs to rotate to keep a human (70kg) unrestrained freely rotating around the inside of the wheel?

    And secondly, how to calculate the varying G-forces exerted at the bottom, top and sides of the wheel.

    Thirdly, I am assuming that theoretically it would be possible for the human to then begin to walk a long the inside surface during the rotation?
     
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Mar 17, 2013 #2

    phinds

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    Do you have any idea how to go about doing the calculations you are asking for? It is not the intent of this forum to simply provide answers. If you try it yourself and get stuck, we're here to help.

    If you know absolutely nothing about how to do this, then perhaps you should think of a different project.
     
  4. Mar 17, 2013 #3
    edit- didn't see reply #1 when I clicked reply! Not sure what to do now...



    The person is most likely to fall when at the very top of the wheel, and at a certain rotational speed, the force required to keep him in circular motion can be made equal to his own weight (which acts through the axis of rotation). You can find this by equating the two quantities, mg = mrw^2. The weight of the human doesn't play a part in the calculation after cancellation, and if r = 30 then it leaves you with an angular speed of sqrt(10/30) = 0.58 rad/s.

    At this point the reaction from the floor will be momentarily zero, and the g-force is zero because the man is essentially in free-fall. Regarding the rest of the rotation, the force that the rotating man experiences (in his non-inertial frame) is mg from gravity (down) plus mg from centrifugal (outward). The highest force he feels is at the bottom where it is exactly 2G.

    It should be possible to walk along the inside certainly, although it will be very tricky as the reaction force below his feet goes from 0 to 2G every 6 seconds.
     
  5. Mar 17, 2013 #4
    Sorry phinds, for not posting my attempt. As you can see its my first post. I did an A level in physics, but it was a while ago. My brain has since been filled with architectural jargon.

    And thank you very much MickeyW. This is actually what I got but for some reason I thought it seemed too little a value.

    I see a very interesting architectural proposition coming out of this.

    Reminds me of this project. http://www.julijonasurbonas.lt/p/euthanasia-coaster/

    Thanks guys.
     
    Last edited: Mar 17, 2013
  6. Mar 17, 2013 #5
    So just elaborate on this, if the wheel stays at a constant angular velocity of 0.571 rad/s and the radius of the wheel gets altered to 40m.

    Would g increase to 13.04?

    mg=mrw^2
    g=40x0.571^2
    g=13.04

    and thus the force felt at the bottom of the wheel 9.81+13.04 = 2.3G?
     
    Last edited: Mar 17, 2013
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