Posted by: BHL (Knight1285@aol.com) on Mon Jun 11 02:43:22 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

Hi Brian,

A bow and arrow is designed to keep any rotary movement to a minimum. Weak archery equipment might spin the arrows, in conrtast to well-constructed apparatus, which would shoot the arrow in a fairly straight line.

However, gravity has an effect on all objects, including arrows. Even high quality archery equipment must take gravity into account. Next time, in an archery contest, watch how the contestants aim their arrows on an upward angle. Why? Because gravity acts upon the arrow, and pulls it towards the ground. As a result, instead of continuing its aclivity, and instancing pure translational movement in the process, the arrowhead will eventually tip downward, and begin its declivity. As a result, the movement becomes parabolic, and the line that curves into an arc shows the linear and rotational motion can transpire simultaneously.

Please note that I am not saying that a flywheel cannot create tremendous force via pure rotation; this is a physical possibility. What I am arguing is that objects can 1) translate, 2) rotate, or 3) do both at the same time. I will be more than happy to provide further clarifications upon request.

Best,
BHL
Knight1285@aol.com