Posted by: Brian () on Sun Jun 10 19:08:59 2007

> Hi Jack,
>
> I have read your position on rotation and translation not occuring simultaneously.
>
> However, I will offer proof to the contrary. Jack, take a baseball, and toss it to a partner at a short distance, throwing the ball as straight as possible. After a few tosses, asks your partner whether or not the ball spins.
>
> When performed, you will discover that the ball travels in a line, or possesses a linear component to it. Yet, the ball also spins, or displays a propensity to gyrate. Moreover, the ball travels in a line and spins simultaneously, showing that linear and rotational activity can be concomitant.
>
> On these grounds, I reject your premise that linear and rotational movement cannot occur at the same time.
>
> Best,
> BHL


BHL, this was not only of your stronger rejection attempts. Quite simply, your example is like suggesting that an arrow shot from a bow is moving both linear and rotational since it spins as it flys straight toward the target. You have simply given one of a million examples of an object moving straight while spinning.

I realize that you are at a disadvantage with a protractor instead of motion analysis software, but your focus should be on the path of the arms in the swing (or the path of the arrow/ball) - not the spinning action (in fact, arms can't spin like an arrow). Check back once you figure out how to make the arrow curve in the air because then we'll have something to talk about ...

Brian