On Wed, 9 Oct 1996, Zhiyong Zhao wrote:
> You can balance 3 tubes in a 12-hole rotor. However, when you add another 2 tub
> es in you actually disturb the first balance and creat a new unbalanced situati
> on. So, each 3-tube or 2-tube group can be balanced, but putting them together
> you will have a totally different thing.
Not at all!!!
If you have a balanced situation (sum of force vectors equals zero) and
you add another balanced situation (sum equals zero), adding both still
results in zero: they are balanced, of course!
Just think of it: the three are balanced when placed in the corners of an
equilateral triangle. Then you add one more anywhere, and another one
exactly opposite, these two will cancel eachother out...