tag:blogger.com,1999:blog-5384583593570605585.post4177870531535276900..comments2022-12-02T17:47:09.350-08:00Comments on Let's Talk Physics: GyroscopesWill Nelsonhttp://www.blogger.com/profile/00289187877856552901noreply@blogger.comBlogger16125tag:blogger.com,1999:blog-5384583593570605585.post-52206673180624001202013-10-02T02:49:02.612-07:002013-10-02T02:49:02.612-07:00Good explanation. Possible to add the equation bal...Good explanation. Possible to add the equation balancing the precision & tipping torque?<br />ThanksAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-85808631023795949792012-12-27T10:06:17.357-08:002012-12-27T10:06:17.357-08:00You will notice a similar effect if you spin pipe ...You will notice a similar effect if you spin pipe and you pump water through pipe at the same time ;)Igor Karlićhttps://www.blogger.com/profile/16554569658309171378noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-19924325570879867572012-12-27T10:04:47.367-08:002012-12-27T10:04:47.367-08:00This comment has been removed by the author.Igor Karlićhttps://www.blogger.com/profile/16554569658309171378noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-48492002543425296202012-12-27T09:47:33.646-08:002012-12-27T09:47:33.646-08:00This comment has been removed by the author.Igor Karlićhttps://www.blogger.com/profile/16554569658309171378noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-16772179032485509182012-03-14T11:45:04.481-07:002012-03-14T11:45:04.481-07:00Figure A: the particle under the red arrow (r) has...Figure A: the particle under the red arrow (r) has an absolute speed relative to the ground smaller than the particle under the blue arrow (b). because of physical constraints, the two particles are rotated by the gyroscope's fall to the right within vertical parallel planes. as a result, the centripetal force caused by the fall to the right which acts upon r is smaller than the one which acts upon b. as a result, the gyroscope moves as shown. <br /><br />Figure B: because of the rotation of the gyroscope explained in Figure A, r moves slower than b and the moment relative to the horizontal axis prevents the gyroscope from falling.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-45268018919159736492012-03-14T11:11:07.234-07:002012-03-14T11:11:07.234-07:00Figure 1: The particle under the red arrow (r) has...Figure 1: The particle under the red arrow (r) has an absolute speed relative to the ground smaller than that of the particle under the blue arrow (b). Therefore the vertical components of the speeds of r and b are different. Because the trajectories of r and b caused by the gyroscope's fall towards the right are within vertical parallel planes, the moments they exert upon the vertical axis are different. As a result b pulls the disc to the right stronger than r and the gyroscope rotates as shown. Does this explanation make more sense, because the explanation in the article is not convincing.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-48530206593350128652010-10-16T22:47:02.599-07:002010-10-16T22:47:02.599-07:00Hi Akash,
Definitely, it is friction that damps t...Hi Akash,<br /><br />Definitely, it is friction that damps the gyroscope. Both the friction of the rotating disk, and the friction of the base against its support, which will rub as it precesses around.Will Nelsonhttps://www.blogger.com/profile/00289187877856552901noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-30937032688909101382010-10-13T21:01:36.456-07:002010-10-13T21:01:36.456-07:00Hi,
I found your post extremely informative.But I...Hi,<br /> I found your post extremely informative.But I couldn't understand your explanation of dampening of gyroscope.I friction doesn't cause,what does?akashnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-84242520000926005262010-03-06T17:49:36.497-08:002010-03-06T17:49:36.497-08:00Hi Nathan,
Yes, a qualitative understanding of th...Hi Nathan,<br /><br />Yes, a qualitative understanding of the force diagram was my aim in this posting. To draw the full force diagram is too complicated because the gyroscope is a rigid body with many internal forces. <br /><br />But for starting the precession, the important forces are which go from the gyroscope body to the moving masses on the sides of the gyroscope, and from those masses back to the rest of the gyroscope, as I indicated on the figure. These backreaction forces (Newton's third law) are what turn the gyroscope. Or more precisely, they cause its base to exert force on the ground, and the backreaction force from the ground turns it.Will Nelsonhttps://www.blogger.com/profile/00289187877856552901noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-12437652905470591842010-03-06T14:03:50.985-08:002010-03-06T14:03:50.985-08:00Your description of how the force of gravity on di...Your description of how the force of gravity on different points on the rim of the gyroscope causes movement perpendicular to gravity and the initial axis of rotation is unclear to me.<br /><br />Can you provide a Newtonian description of all the total forces, their sum and net force, for each point on the gyroscope?<br /><br />I am looking for a description that can be used to show the net force on the gyroscope as a whole at each particular point in time, from the initial setup (no precession), to the acceleration increasing the rate of precession, to its final state of equilibrium.Unknownhttps://www.blogger.com/profile/10513857227013997172noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-89609710589845296912009-11-04T16:44:24.548-08:002009-11-04T16:44:24.548-08:00Thank you very much for the most easiest and intui...Thank you very much for the most easiest and intuitive explanation.<br />I will have other pilots see this post.sung hyuknoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-13901425420264763292009-10-26T20:46:22.656-07:002009-10-26T20:46:22.656-07:00@Sung:
Sorry, and when I say "outward", ...@Sung:<br />Sorry, and when I say "outward", I also mean "away from the base".Will Nelsonhttps://www.blogger.com/profile/00289187877856552901noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-29229019112096854052009-10-26T20:45:25.541-07:002009-10-26T20:45:25.541-07:00@Sung: You're right, my directions are confusi...@Sung: You're right, my directions are confusing! When I say right/left, I am imagining looking at the gyroscope from the front, i.e. from the side opposite from the base. <br /><br />@Steve: It is a misconception that one needs special concepts to understand motion. Those concepts are useful for calculation, but they get in the way of actual understanding. Check out Newton's 3 laws - the laws which govern all mechanics. They do not mention angular momentum or torque; therefore, the true explanation of the phenomena does not depend on angular momentum or torque.Will Nelsonhttps://www.blogger.com/profile/00289187877856552901noreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-54303041943354269172009-10-26T13:51:52.419-07:002009-10-26T13:51:52.419-07:00Just to be clear what my questions are about....
...Just to be clear what my questions are about....<br /><br />When you wrote <br /><br />"The side which is attempting to change its motion in the "outward" direction ( the right hand side in Fig. A) will flex inwards."<br /><br />What way is the "outward" directed and what part is the right hand part? <br /><br />Big thanks in advancekohsunghyuk@hotmail.comnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-41876157898666484942009-10-26T13:40:18.245-07:002009-10-26T13:40:18.245-07:00Hi, Thanks for the great post.
I am a CFI ( Certif...Hi, Thanks for the great post.<br />I am a CFI ( Certified flight instructor) student and have been searching for an intuitive way of explaning how and why a gyroscope precess and your explanation seems to offer the easiest way in understanding the mechanics of a gyroscope without resorting to the angular momentum and vectors etc.<br /><br />However some of the comments seem to have make the whole thing a bit confusing; for example, when you talk about figure A, I have not been able to understand how the flexes and directions of movement ( inward, outward, left and right) are directed. Does "inward" mean moving towards the paper from me and "outward" towards me from the paper?<br /><br />Help needed, please.<br /><br />My email address is kohsunghyuk@hotmail.comSung hyuk Kohnoreply@blogger.comtag:blogger.com,1999:blog-5384583593570605585.post-53164886011422623622008-07-28T08:00:00.000-07:002008-07-28T08:00:00.000-07:00Sorry, but I find this explanation confusing. Sta...Sorry, but I find this explanation confusing. <BR/><BR/>Start by imagining two single point masses held equidistant from a central shaft of no mass. Now imagine these two masses rotating about that shaft. This is a pretty simple model of a gyroscope. <BR/><BR/>Imagine that we wish to move the two masses parallel to the shaft. We apply a force in that direction and everything moves as expected. <BR/>Imagine next that we wish to translate the two masses in the plane they describe with the shaft. Same thing. And the same for uniform motion in the third direction. Superposition applies to such linear models, so our intuition works well in understanding the results.<BR/><BR/>Next, we try rotating shaft of the spinning gyroscope in a direction that reorients it in space The problem here is that the motion we are imparting is not rectilinear. And if one tries to understand it without some understanding of the models that govern non-rectilinear motion one ends up with nonsense. <BR/><BR/>Intuitively, one must grasp that there is a kind of rotational inertia (technically it's rotational momentum) that is related to the radius of curvature and the instantaneous velocity of the particle. And that reorienting the shaft necessarily involves changing that rotational momentum because the momentum has both a magnitude and a defined direction. <BR/><BR/>(Draw the freebody diagrams of the two masses. Under translation the accelerations associated with changes in direction for each particle create moments on the shaft that will cancel out. Under shaft rotation, they will add. This is why rotation and linear motion are governed by different models)<BR/><BR/>Tiny forces can make slow changes to the rotational momentum of the gyroscope. And, in fact, precession is a consequence of the force of gravity on a gyroscope whose poles are not aligned with the gravitational field. Precession is a motion that arises as a result of a gravitational turning moment applied to the shaft of the gyroscope. <BR/><BR/>One might observe that the shaft tends to rotate in space perpendicularly to the direction of the force one applies to it. One can write the equations. One can get used to the phenomenon; but until one has solved a lot of such problems it is always counterintuitive.<BR/><BR/>It's not clear to me that one can say much more without resorting to writing equations.Anonymousnoreply@blogger.com