Many thanks Sean for these final
video tests.
So the final word about this kind of spinner must be:
It only works from the moving input of the hands of the experimentator.
Many thanks for these tests so we can move on to a different device.
Hi,
I have scanned this thread for the same analysis as mine and I did not see a similar take on the device, so here goes:
To put a finer point on the device:
A. The ring of magnets serves to help provide a vertical 'hold' to the axis of the spinner. Statically, you can hold the spinner vertical (axis) to the table, desk, whatever. If the ring mags are strong enough the spinner does not need to 'spin' to stay vertical.
B. Device will not work if the Spinner's axis is sharp-pointed or in a bearing.
B1. Spinner contact with table must be a spherical surface in contact with the table or a small diameter, flat end (flattened point).
C. The effect is a delicate concert played out by the interactions between friction, linear motion and gyroscopic precession.
Cause & Effect:
1. The ring holds the spinner central and vertical from above (the spinner is trying to hang from the ring).
2. Stationary ring
tends to cause the spinner to spin vertical as the surface in contact with the table causes the spinner (gyro) to nutate (see definition:http://en.wikipedia.org/wiki/Nutation)
3. As the ring is translated (moved) horizontally by the experimenter, the friction of the spinner's contact point on the table causes a resistance of the spinner to translate horizontally with the ring across the table thus imparting a 'tilting'
force to the axis of the spinner (gyro).
4. The spinner (gyro) precesses (see definition:http://en.wikipedia.org/wiki/Gyroscopic_precession#Torque-induced) in response to the 'tilting'
force causing the spinner (gyro) to 'tilt' 90 degrees to the applied force.
5. The leaning causes the contact point between the spinner axis and the table to NO LONGER be a point (in effect) but is now a small diameter contact, or minor circle (if spherical), or a circumferential 'edge' (if round and flattened ... not pointed). As the motion of the ring continues, precession of the spinner (gyro) continues to lean (precess) in in the same direction.
6. In effect you have a 'wheel' or 'tire' on the table (albeit slanted a great deal) slowly driving the axis along 'beneath' the spinner in the direction of the ring's movement while the ring is keeping the upper portion of the spinner central to itself.
7. As you translate the ring horizontally, rotational force is imparted to the axis of the spinner by the friction between the end of the spinner axis and the table. Because this 'minor circle' is so small you have a 'speed increaser", in effect (just like a flywheel on a tiny shaft that you can spin to great RPM in a finger-to-palm swipe of your hands).
7a. It just so happens that the direction of precess and the direction of travel compliment each other ... thank goodness for the
right-hand rule of torque, spin, and precession vectors for gyroscopes.
8. If horizontal translation of the ring stops, the spinner nutates in position until friction brings it to a hault.
9. There is also a minor interplay between the precession and nutation but it is more complicated to explain
that than what has been laid out above.
"Well, there it is." (quote from Dr. Ian Malcolm - Jurassic Park)
Greg