The Perfect Spin

[PatMc2012]

Hi, Just a thought I can't shake, If somehow I managed to balance a Perfect Sphere on a pin head & then perfectly spin the sphere, I'm thinking the sphere would spin for a very, very long time. Any feedback would be great, Thanks

[md65536]

Hi, Just a thought I can't shake, If somehow I managed to balance a Perfect Sphere on a pin head & then perfectly spin the sphere, I'm thinking the sphere would spin for a very, very long time. Any feedback would be great, Thanks

 

I'm guessing that a pin head that's not concave would contact a perfect sphere at a single point?

Then is should be the same as if you spun the sphere on a perfect horizontal plane (also a single contact point)?

 

I don't think such a thing is physically possible, but I guess theoretically it would have no drag?

Would the friction on the point be zero if the the contact was a single point? If no, I'd guess that the weight of the sphere would be a major factor (heavier = more friction). Or would a perfect sphere have no friction even on any surface, even held in your hand???

 

I would even guess that if it was really perfect, then relativistic frame dragging might be the biggest factor in slowing it, or generation of heat from tidal forces, or changing magnetic forces or something??? All very small I'd guess.

 

In conclusion: I don't know! I think so!

[PatMc2012]

Thanks for reply, Yes, Say both contact points where "Diamond Plated" the closest you could get to zero friction, because if there was zero friction they would be no energy loss? Ok how about floating a Magnate Sphere over another magnate, that would work a hold lot better, For example: if I build a room from North charged Magnate & put a South charged Magnate Sphere in to it, in theory it should float in the middle, equal presure from all side would cancel each other out? the energy I spin the sphere with would take an extremely long time to leave the sphere, Perhaps years. I noticed once where I closed the door behind me, I'd a set of keys in them, one key in lock the other hanging joined by key ring, I noticed later on that evening that the bottom key way still moving, that what got me thinking of how to store energy in objects?

[Joatmon]

I thought at first that the question was about balance. For example it can be shown mathematically that a sharp pencil can be balanced on it's tip and remain in that position. However the condition is not stable and the slightest disturbance will see the pencil topple.

Then I realised you are talking about the flywheel principle. A heavy flywheel on perfect bearings and with absolutely no losses such as friction with the air will (theoretically) spin for ever. However you input energy to get the flywheel spinning and if you try to take energy from it then it will slow down. You can never get more energy out of a spinning flywheel than you put into it initially. In other words a spinning flywheel stores energy. Of course you cannot create a condition of no losses so the flywheel will gradually lose energy feeding those losses and eventually come to a stop.

Edited May 14, 2012 by Joatmon

[PatMc2012]

Thanks Joatmon, so in reality even if I float the sphere there will still be a loss in energy over time & creating a "space like" atmosphere on earth is impossible, the force at the point of contact between the two objects is determined by the weight of the object on top & gravity pushing down, in other words is that force at that point energy that can be used ? & if so can it be transferred to spin the object ?

[Joatmon]

Looks like you are chasing a perpetual motion machine driven by gravity. Many people have constructed many machines of many types in an attempt to realise this dream. Unfortunately none has worked. If you google - gravity perpetual motion - you will easily find many examples.

My field is electronics, but as I understand it force itself is not energy. If the force moves something in the direction of that force then work is done and so energy is being used. If the contact between your sphere and its bearing is allowed to move towards the centre of the earth then while it is moving you can make a device which can extract energy which could be used to maintain the rotation. However this movement obviously cannot be maintained. If I haven't got this quite right no doubt someone with mechanical experience will say something!

Edited May 14, 2012 by Joatmon

[PatMc2012]

So when you create something you have to consider how you can exchange the force for energy, Ie. Fill a tank with 10 ton of water, put a hole in tank, that's your energy coming out, what happens to the energy in 10 ton of lead ? Is it trapped within ? Now I know lead is man made so maybe the exchange happens there, For example Diamons take 1000s of years to form, the energy they give out is resistance to certain things, With that in mind I think I may have awnsered my question, We can create stored energy & there is allways a way to create energy from it, the ways we transfer that energy can differ greatly from one thing to the other.

[Joatmon]

We are getting further away from my field of experience. It seems you are getting into Einstein's famous equation E=Mc^2. At this point I'd better bail out and see what other responses you get!