0
$\begingroup$

In the classic example of gyroscopic precession, the wheel starts to process, and now acquires a angular moment also in the vertical direction. Initial angular momentum was in a single plane. The one due to the spin, and the one due to self-weight).

enter image description here

How is this new vertical angular momentum induced mechanically? Does this mean the new net angular momentum is no longer in the initial plane?

$\endgroup$
2
$\begingroup$

The mechanism of inducing the precessing motion is discussed by me in a 2012 stackexchange answer to the question what determines the direction of precession of a gyroscope

The start of the precession inducing conversion is that the center of mass drops. If the gyroscope wheel is spinning very fast the drop is not visible to the naked eye. Presumably this explains why the drop is very rarely mentioned. It seems likely to me that many textbook writers are unaware of the drop. Many textbook authors seem to imply that the precessing motion happens instead of dropping down. In actual fact there is a conversion (as mentioned, with the gyroscope wheel spinning very fast the conversion is near instantaneous.)

One way to confirm the drop is to try a range of spin rates. The slower the spin rate of the gyroscope wheel the larger the drop.

The drop has been verified experimentally. Paper by Svilen Kostov and Daniel Hammer: 'It Has to Go Down A Little, In Order to Go Around'- Following Feynman on the Gyroscope

Your second question was answered implicitly in the above, explicitly now:
Yes, the new net angular momentum is no longer in the initial plane.

| cite | improve this answer | |
$\endgroup$
  • $\begingroup$ Yes, the new net angular momentum is no longer in the initial plane --The torques that we apply result in the angular momentum being on the same plane. Which torque has resulted in the new vertical angular momentum? $\endgroup$ – Sridhar Thiagarajan Aug 2 '18 at 15:51
  • $\begingroup$ @SridharThiagarajan The dynamics that you ask about is described in the 2012 answer that I linked to. The information necessary to figure things out is there. $\endgroup$ – Cleonis Aug 2 '18 at 23:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.