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23 November 2024 18:01
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Welcome to the gyroscope forum. If you have a question about gyroscopes in general,
want to know how they work, or what they can be used for then you can leave your question here for others to answer.
You may also be able to help others by answering some of the questions on the site.
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Question |
| Asked by: |
Nitro MacMad |
| Subject: |
oscillation tranfer |
| Question: |
Dear D Brown and the rest of the gang,
The demonstration you mention in the general section of this forum, of the increasing orbit of a gyro hung from a long string and released with its axis horizontal (it doesn’t have to be exactly horizontal for this), interestingly shows two transferring oscillating functions. After the orbit has, as you so youthfully put it, “maxed out” it will gradually “min in” to its start point and axial angle (less friction’s toll) whereupon it will proceed to “max out” again. Weird aint it?
A simple to try experiment to more clearly understand two transferring oscillating functions can be done with a “slinky” toy spring (the kind of toy spring that climbs down stairs - if that isn’t an oxymoron).
Attach a small weight to the last coil of the spring (not too heavy as you don’t want to overstretch the spring) and the top of the spring to the top of a stair well so the slinky is allowed to carefully extend till it stops. If the weight is raised as small amount (so as not to over stretch the spring when released) and released, the spring will (as most would expect) oscillate up and down. After a while however the spring will start to do something totally different.
Try this experiment and let me know you have by telling me what happens next? Or, if you must be lazy, just guess the outcome!
Kind regards
NM
PS Many people on and off this site have expressed that nutation causes precession indeed, in one of your posts you use nutation instead of precession.
Precession is the transfer of a force acting to change the axial angle of a gyro into a rotational speed of the axial angle change, ninety degrees from the applied force. This, as you have seen in the video lectures demo with a gyro with springy balls (you should excuse the expression), is caused purely by the conservation (perhaps better described in the case of a gyro as the “conversion”) of angular momentum. No other mystery driving force, nutation, slowing of gyro spin, or any other, is needed. Just as no other mystery force is needed to explain that your rotational speed will increase if you draw in your arms while spinning on ice.
Nutation is an over and under shoot of the displaced ninety degree angle of precession of the axial angle, caused by too great an applied force in relation to the gyro’s spin speed and mass.
If the gyro’s spin speed and mass is very small, in relation to the force applied to change the axial angle, the nutation just like any undamped oscillating system will increase to its maximum as the gyro converts from gyrodynamics to Newtonian dynamics.
The converse (a small force and high spin/mass) would show a fast settling, nigh invisible, nutational oscillation. Same as effect of good dampers and low unsprung weight on a car suspension, same as the effect of negative feedback on an operational amplifier, same as … well, you get the picture. Get the balance right (dam nigh impossible with handlable mass) and the nutation remains steady like the apparently steady, tiny nutation of the Earth.
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| Date: |
16 August 2005
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| report abuse
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Answers (Ordered by Date)
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| Answer: |
dave brown - 16/08/2005 18:54:06
| | | Hi Sandy,
I won't be buying a slinky but have a wee plastic one that I don't think will work. I may try.
I think I understand the gyro on string.
When my bicycle wheel is pointing down, it tries to slip off my finger.
- centrifical?
When it is pointing up, I have to keep it from sliding too far on, then off my finger.
- centripital?
I do turn with the wheel. Those 2 things coincide with the video.
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| Report Abuse |
| Answer: |
Nitro MacMad - 17/08/2005 21:04:36
| | | Dear David “Brown”,
Let me guess Dr Fisher, it’s just before university term starts, there are loads of computers to access the web with and, before the students arrive, it is as boring as hell. Come on! Use, don’t abuse, your intellect!
Sandy does not need to use a pseudonym. I do and am happy to admit it. Sandy has done far more than I in engineering effort in this field and has suffered the sticks and stones from people who have done nothing in honest effort to extend human understanding. Such people seem only able to lift their self image by trying to destroy others. That alone would seem to me to be sufficient justification to hide behind a pseudonym (even a crap one like Nitro MacMad). It also means that if I am unsuccessful in my efforts the embarrassment is limited and, if by some miracle, I am successful the disruption to my life will be minimised.
What do you want to achieve from your writing to this site? I hope to share in the efforts of others, share some of the things I have found, and throw in the odd bit of English humour when my gout and grumpiness allows.
NM
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| Report Abuse |
| Answer: |
dave brown - 18/08/2005 00:25:53
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I thought this was a public forum.
Are you telling me to stop?
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| Report Abuse |
| Answer: |
dave brown - 18/08/2005 00:34:55
| | | Don't answer.
I thought Sandy had made the first post in this thread.
Why you came back with what you said as if I had answered to you I still don't get,
I meant no offence.
The negative vibe I got from your words prompts me to suggest you recheck which people are showing what about certain areas of their intelect.
No hard feelings. We obviously grind against each other.
Lets stop the pain now and thread our seperate ways.
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| Report Abuse |
| Answer: |
dave brown - 28/08/2005 17:46:23
| | | Ahhhhh,
I believe you were speaking of the oscillation(s) within the gyro itself.
- I'm getting up to speed. Slowly but funly. lol :)
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