Posted by Jonathan (68.14.212.239) on October 20, 2003 at 02:26:55:
In Reply to: Re: Gyros (my tippe top extension) posted by Øystein Rustad on October 19, 2003 at 15:51:14:
I have redone my thinking and I think it does lift its center of mass. I don't know if it is free or reduces RPM, it's been a while since I have played with one. I tried to make one today and it didn't work, as soon as I can I will go buy one.
: : The 'tippe top' does not raise its own centre of mass without expending energy to do so - ie: lifting its mass costs RPM.
: I hear ya :-)
: But the "problem" is : How can the RPM be reduced in the Tippe Top ? To slow down a moving object, some kind of oposing force must act...
: The mathematics I saw showed that surface friction was the only place the energy went...?
: But that don`t seem completely conserving to me ?
: : Gyro RPM can transform into precessional torque and visa-versa. Laithwaite demonstrationed the lifting of heavy spinning gyros high above his head with little effort, but the energy for the lift is at the expense of rotational momentum. No free lunch, but very interesting mechanics.
: : On the other hand, a gyro can be driven to higher RPM by applying timed precessional torque, as with the "powerball" hand held gyro excerciser/toy. Check out the link - http://www.powerballs.com/what.html - it's an interesting and educational device. Again, the energy equation perfectly balances. Fascinating none the less.
: : Regards, ovyyus
: :
: : : I too have been interested by gyros, and have noticed an interesting effect. If a nonspinning gyro is hung from a string, it just sits there. If one spins it fast and lifts its axle up to horizontal, it won't fall, but willgo around from precession. However, if one connects another string from the other end of the axle to the point of suspension so that the axle and original string have a 90 degree angle AND the gyro is not spinning, the whole thing tilts so that the center of mass is below the suspension point. So why does this not happen when spinning? I'll have to send a picture to scott...