LETTERS 

 

To Spin Or Not To Spin

Should a juggling ball spin? All the other types of juggling involve spinning the object. The answer is obvious with gyroscopic juggling such as diabolos, tops and yo-yos. And if you assume that a pendulum is merely a gyroscope that stops and then reverses its direction then you would say that devil sticks also spin. (This is another question I put to the more physical IJA members, "Is a devil stick a gyroscope?")

 

The two other toss juggling items, rings and clubs, certainly are easier to handle when spinning than when thrown flat. Hat manipulators spin their hats. Boomerangs turn or do not come back.

 

In volleyball the most difficult serve to return is one that is hit with no spin at all. A spinning volleyball has a more predictable path and is easier to track. I realize that a volleyball is a bit heavier at the nozzle and it is the random, erratic movement of the off­center ball that causes the difficulty of reception when served with no spin. Still, I wonder if a spinning juggling ball is more predictable and/or easier to handle than a non-spinning one?

 

A golf cub is designed to hit a golf ball to spin and stay aloft longer because of friction with the air caused by the rapid rotation of the ball. Misapplication of this spin principle vexes the suffering many who hit slices or hooks.

 

In average juggling the rpm's are so slow and the height is so low as to be unnoticeable. But let's increase things by a factor of ten. Imagine a Super Rastelli who is trying to juggle 100 balls. Should she or he throw a juggling ball with spin or without spin?

Todd Strong - Berlin, Germany