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Understanding gyro without angular mom

  1. Sep 20, 2008 #1

    I understand the motion of a gyroscope through considerations of torque and angular momentum, I have no issue with deriving it and imagining it by considering these things, but I somehow feel I still don't understand precession on an intuitive level. I was wondering if anyone could help me understand the motion of a gyroscope without invoking angular momentum/torque, just by soley considering Newton's laws.

    Just to avoid confusion, take the z axis as out of the screen, y-axis from bottom to top, x axis from left to right and I'm considering a flywheel rotating along an axis in the x-direction. Its axial rod is sat on a pivot to the left, gravity is in the negative z direction. Hence torque is in the y-direction, and precession occurs about the z axis.
    I've attempted a drawing, that I've attached.

    Like I say, I'm happy with the ang mom/torque explaination, Im just looking for a Newtonian one.


    Attached Files:

  2. jcsd
  3. Sep 20, 2008 #2


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    Don't be afraid of angular momentum. You really need it here.
    Even Newton used it.
  4. Sep 20, 2008 #3
    I'm not afraid of angular momentum, I fully understand the explanation of precession via angular momentum and torque, and no issues with it at all. However I have an itching to understand this via simple forces as well, ultimatley such a picture must be possible here. I think that thinking of the flywheel as a composite object, made up of smaller particles, some of which are moving up, some down, some left some right, etc, when the flywheel spins, is key to understanding why the flywheel precesses when spun, but falls otherwise. Can't quite fully picture it just yet though.
  5. Sep 21, 2008 #4
    I never understood gyroscopes (I still dont) until I read the ping pong ball on a string explanation. as the ball circles around each time it strikes a paddle and glances off at a very slight angle. the result is a downward force on the paddle. you can then easily imagine the effect on the ping pong balls rotation.
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