Fidgets Spinning

[Norbert]

Hi I was playing with my daughter's fidget and was wondering how should I hold it in order for it to spin the longest amount of time. Verticlly, horizontally or at an angle in between?

Any suggestions?

 

[exchemist]

Hi I was playing with my daughter's fidget and was wondering how should I hold it in order for it to spin the longest amount of time. Verticlly, horizontally or at an angle in between?

Any suggestions?

I don't know what the bearing design is - my son talks about them but has not yet succumbed.

 

If it is a rolling element bearing then I would expect it to suffer the minimum energy loss when held with the axis of rotation horizontal. This will allow the weight to be taken entirely on the elements (balls or rollers) rather than a portion of it being carried by sliding contact between the inner and outer bearing housings. But try it and let us know if you see any difference.

Edited May 23, 2017 by exchemist

[Norbert]

Thanks! in order to do that i would need to apply exactly the same torque in exactly the same conditions since the difference one way or the other will be minimal.

I was wondrering if there is a mathematical way to find out.

[exchemist]

Thanks! in order to do that i would need to apply exactly the same torque in exactly the same conditions since the difference one way or the other will be minimal.

I was wondrering if there is a mathematical way to find out.

I don't think there can be. If the bearing were frictionless and there were no air resistance then it would spin forever, irrespective of the direction. So from the viewpoint of simple mechanics I don't see any distinction between directions.  What you are effectively asking is whether the friction that eventually slows it in practice depends on orientation relative to the force of gravity. This seems to me to be a question of engineering - of bearing design.

[sanctus]

My 2 cents is, if the rotation axis is horizontal then gravitational effects cancel out (the side spinning down gets pulled down by a force of same magnitude then the side going up is slowed down), while if the rotation axis is vertical you loose spin continuously due to gravity. If in addition we a are in the real world the latter case also slows it more due to more friction (i.e the whole bearing is pulled down to the casing vs only the lower half).
In conclusion I can't see any reason why vertical or diagonal rotational axis should be preferred. But since you ask the question, I guess I am missing something...